Anaesthesia essentials: Articles

Abstract
In 2023, a Diploma of Rural Generalist Anaesthesia (DipRGA) was implemented across Australia. Developed collaboratively by the Australian and New Zealand College of Anaesthetists (ANZCA), the Australian College of Rural and Remote Medicine (ACRRM) and the Royal Australian College of General Practitioners (RACGP), the 12-month qualification is completed during or following ACRRM or RACGP Rural Generalist Fellowship training. Focused on the needs of rural and remote communities for elective and emergency surgery, maternity care, resuscitative care for medical illness or injury, and stabilisation for retrieval, the DipRGA supports rural generalist anaesthetists working within collaborative teams in geographically isolated settings. The goal is a graduate who can anaesthetise American Society of Anesthesiologists physical status class 1, 2 and stable 3 patients for elective surgery, provide obstetric anaesthesia and analgesia, anaesthetise paediatric patients and undertake advanced crisis care within their scope of practice. Crucially, they also recognise both limitations of their skills and local resources available when considering whether to provide care, defer, refer or transfer patients. DipRGA curriculum design commenced by adapting the ANZCA specialist training curriculum with consideration of the training approach of both the ACRRM and the RACGP, particularly the rural and remote context. Curriculum content is addressed in seven entrustable professional activities supported by workplace-based assessments and multisource feedback. Trainees are supervised by rural generalist anaesthetists and specialist anaesthetists, and complete flexible learning activities to accommodate geographical dispersion. Standardised summative assessments include an early test of knowledge and an examination, adapted from the ACRRM structured assessment using multiple patient scenarios.

Abstract
Purpose: Gas leakage around the cuff of a tracheal tube may frequently occur after tracheal intubation and inflation of the cuff. We assessed if the SmartCuff (Smiths Medical Japan, Tokyo, Japan), an automatic cuff pressure controller, would effectively prevent gas leakage.

Methods: Seventy adult patients were allocated randomly to one of two groups. After induction of general anesthesia and tracheal intubation, in one group (Syringe group), a syringe was used to inflate the cuff, until there was no audible gas leakage, at the airway pressure at 20 cmH2O. In the other group (SmartCuff group), the SmartCuff was used to maintain the cuff pressure to be 20 cmH2O. The mechanical ventilation (tidal volume of 8 ml.kg-1 and 12 breaths per min) was started. The incidence and percentage of gas leakage, and the proportion of adequate seal (defined as gas leakage of < 10%) between the groups were compared.

Results: The incidence of audible gas leakage was significantly higher in the Syringe group (10 of 35 patients (28%)) than in the SmartCuff group (none of 35 patients (0%)) (P = 0.00046, 95%CI for difference: 15-43%), and the proportion of adequate seal was significantly lower in the Syringe group (19 of 35 patients (54%)) than in the Smart cuff group (33 of 35 patients (94%)) (P = 0.0001, 95% CI for difference: 20-58%).

Conclusion: Gas leakage may frequently occur after tracheal intubation, and the use of the SmartCuff can effectively maintain the sealing effect of the cuff.

Abstract
Minimally invasive cardiac surgery (MICS) has been used since the 1990s and encompasses a wide range of techniques that lack full sternotomy, including valve and coronary artery graft surgery as well as transcatheter procedures. Due to the potential benefits offered to patients by MICS, these procedures are becoming more common. Unique anaesthetic knowledge and skills are required to overcome the specific challenges presented by MICS, including mastery of transoesophageal echocardiography (TOE) and the provision of thoracic regional analgesia. This review evaluates the relevance of MICS to the anaesthetist and discusses pre-operative assessment, the relevant adjustments to intra-operative conduct that are necessary for these techniques, as well as post-operative care and what is known about outcomes.

Abstract
Background: Opioid-free anesthesia (OFA) is increasingly being adopted to reduce opioid consumption, but its impact on early postoperative recovery following major surgery has not been evaluated in comparative trials. We hypothesized that an OFA protocol would enhance the early quality of recovery (QoR) for patients undergoing scheduled major surgery under general anesthesia.

Methods: The SOFA study was a monocentric, randomized, controlled, assessor- and patient-blinded clinical trial conducted from July 10, 2021, to February 12, 2022. The eligible population included male and female patients undergoing scheduled major surgery, excluding bone procedure, that typically require opioids for postoperative pain management. Patients in the intervention group received a combination of at least two drugs among ketamine, lidocaine, clonidine, and magnesium sulfate, without opioids for anesthesia. The standard group received opioids. The primary outcome was early postoperative QoR, assessed by QoR-15 score at 24 hours (H24) after surgery. Secondary outcomes were QoR-15 at 48 hours (H48) and 72 hours (H72) after surgery, incidence of chronic pain, and quality of life at three months.

Results: Of the 136 randomized patients, 135 were included in the primary analysis (mean age: 45.9±15.7 years; 116 females (87.2%); 85 underwent major plastic surgery (63.9%)), with 67 patients in the OFA group and 68 in the standard group. The mean QoR-15 at H24 was 114.9±15.2 in the OFA group versus 108.7±18.1 in the standard group (difference of 6.2, 95% CI, 0.4-12.0; p=0.026). QoR-15 scores also differed significantly at H48 (difference of 8.7, CI 95% 2.9-14.5); p=0.004) and at H72 (difference of 7.3, CI 95% 1.6-13.0, p=0.013). There was no difference in other secondary outcomes. No major adverse events were noticed.

Conclusion: The OFA protocol improved QoR after major elective surgery in a statistically but not clinically significant manner when compared to standard anesthesia.

Abstract
Background: Qualitative data on the opinions of anaesthesiologists regarding the impact of peri-operative night-time working conditions on patient safety are lacking.

Objectives: This study aimed to achieve in-depth understanding of anaesthesiologists' perceptions regarding the impact of night-time working conditions on peri-operative patient safety and actions that may be undertaken to mitigate perceived risks.

Design: Qualitative analysis of responses to two open-ended questions.

Setting: Online platform questionnaire promoted by the European Society of Anaesthesiology and Intensive Care (ESAIC).

Participants: The survey sample consisted of an international cohort of anaesthesiologists.

Main outcome measures: We identified and classified recurrent themes in the responses to questions addressing perceptions regarding (Q1) peri-operative night-time working conditions, which may affect patient safety and (Q2) potential solutions.

Results: We analysed 2112 and 2113 responses to Q1 and Q2, respectively. The most frequently reported themes in relation to Q1 were a perceived reduction in professional performance accompanied by concerns regarding the possible consequences of work with fatigue (27%), and poor working conditions at night-time (35%). The most frequently proposed solutions in response to Q2 were a reduction of working hours and avoidance of 24-h shifts (21%), an increase in human resources (14%) and performance of only urgent or emergency surgeries at night (14%).

Conclusion: Overall, the surveyed anaesthesiologists believe that workload-to-staff imbalance and excessive working hours were potential bases for increased peri-operative risk for their patients, partly because of fatigue-related medical errors during night-time work. The performance of nonemergency elective surgical cases at night and lack of facilities were among the reported issues and potential targets for improvement measures. Further studies should investigate whether countermeasures can improve patient safety as well as the quality of life of anaesthesia professionals. Regulations to improve homogeneity, safety, and quality of anaesthesia practice at night seem to be urgently needed.

Abstract
Purpose: In hip fracture patients aged ≥ 80 years, we investigated whether the perioperative reduction in the psoas major muscle index (PMI) for spinal anesthesia was less than that for general anesthesia.

Methods: A total of 262 patients surgically treated for intertrochanteric or femoral neck fractures between August 2015 and August 2022 were enrolled. After adjusting for propensity score matching, 50 patients were included in this analysis. After matching, patients were divided into those receiving spinal or general anesthesia. We measured the psoas major muscle area (PMA) by adjusting for the patient's height as PMA (cm2) divided by height (m) squared. The adjusted PMA was defined as the PMI. We calculated the variability in PMI (ΔPMI) before and after surgery. The primary outcome was the proportion of patients with a > 10% reduction in ΔPMI. The secondary outcomes were the mean ΔPMI and estimated factors affecting the postoperative reduction in the PMI. We compared the primary and secondary outcomes between spinal and general anesthesia.

Results: The proportion with a > 10% reduction in ΔPMI did not differ between spinal and general anesthesia (36.0% vs. 40.0%, odds ratio:1.19, 95% CI:0.38-3.72, p = 0.31). The ΔPMI did not differ between spinal and general anesthesia (- 8.7% ± 7.9% vs. - 8.9% ± 8.3%, p = 0.93). The factors affecting the postoperative reduction in the PMI were male sex, preoperative non-sarcopenia, and intramedullary nailing.

Conclusion: There was no significant difference in ΔPMI between hip fracture patients ≥ 80 years of age receiving spinal versus general anesthesia undergoing surgical treatment.

Keywords: Hip fracture; Psoas major muscle area; Sarcopenia.

Abstract
Purpose: As many as 30% of patients with frailty die, are discharged to a nursing home, or have a new disability after surgery. The 2010 United Kingdom National Confidential Enquiry into Patient Outcome and Death recommended that frailty assessment be developed and included in the routine risk assessment of older surgical patients. The Clinical Frailty Scale (CFS) is a simple, clinically-assessed frailty measure; however, few studies have investigated interrater reliability of the CFS in the surgical setting. The objective of this study was to determine the interrater reliability of frailty classification between anesthesiologists and perioperative nurses.

Methods: We conducted a cohort study assessing interrater reliability of the CFS between perioperative nurses and anesthesiologists for elective surgical patients aged ≥ 65 yr, admitted to a large regional university-affiliated hospital in Australia between July 2020 and February 2021. Agreement was measured via Cohen's kappa.

Results: Frailty assessment was conducted on 238 patients with a median [interquartile range] age of 74 [70-80] yr. Agreement was perfect between nursing and medical staff for CFS scores in 112 (47%) patients, with a further 99 (42%) differing by only one point. Interrater kappa was 0.70 (95% confidence interval, 0.63 to 0.77; P < 0.001), suggesting good agreement between anesthesiologists and perioperative nurses.

Conclusion: This study suggests that CFS assessment by either anesthesiologists or nursing staff is reliable across a population of patients from a range of surgical specialities, with an acceptable degree of agreement. The CFS measurement should be included in the normal preanesthesia clinic workflow.

Abstract in English, French
Purpose: In children, the relationship between the dose of intraoperative opioid and postoperative outcomes is unclear. We examined the relationship between intraoperative opioid dose and postanesthesia care unit (PACU) pain scores and opioid and antiemetic administrations.

Methods: We performed a single-institution retrospective cohort study. Patients who were aged < 19 yr, had an American Society of Anesthesiologists Physical Status of I-III, were undergoing one of 11 procedures under general anesthesia and without regional anesthesia, and who were admitted to the PACU were included. Patients were analyzed by quartiles of total intraoperative opioid dose using multivariable regression, adjusting for confounders including procedure. An exploratory analysis of opioid-free anesthetics was also performed.

Results: Three thousand, seven hundred and thirty-three cases were included, and the mean age of included patients was 8.3 yr. After adjustment, there were no significant differences between the lowest and higher quartiles for first conscious pain score, mean pain score, PACU opioid dose, or PACU length of stay; in addition, estimated differences were small. Patients in higher quartiles were estimated to be more likely to receive antiemetics, significantly so for those in the second quartile. Patients in the lowest quartile received significantly more intraoperative nonopioid analgesics. In the exploratory analysis, no significant difference in PACU pain scores was found in cases without intraoperative opioids.

Conclusions: Children who received lower doses of intraoperative opioids did not have worse PACU pain outcomes but required fewer antiemetics and received greater numbers of nonopioid analgesics intraoperatively. These findings suggest that lower doses of intraoperative opioids may be administered to children as long as other analgesics are used.

Abstract
Anaesthetists and pulmonologists are well trained to follow the "can't intubate, can't oxygenate" (CICO) protocol but the procedure is rarely practised. This case report concerns an elective patient scheduled for endobronchial ultrasound bronchoscopy (EBUS) because of suspected sarcoidosis. Based on known medical history, anaesthesia for EBUS procedure was initiated with a laryngeal mask. The airway turned out to be difficult and the patient was not ventilable despite several efforts including curarization and orotracheal intubation. Rapid desaturation imposed to apply the CICO protocol with emergency cricothyroidotomy as extreme measure but also failed. 6-handed face mask ventilation was continued. Eventually, introduction of a microlaryngeal tube of the 3rd generation laryngeal mask, placed on the fibrescope, allowed endotracheal intubation. The patient fell into pulseless electrical activity, and the CICO protocol was started. Immediate cardiopulmonary resuscitation totally recovered vital functions. In the post-operative follow-up, no temporary or permanent cardiological and neurological sequels were found, but new medical history such as inconstant use of C-PAP (Continuous Positive Airway Pressure) and a significant weight gain since the last notable difficult intubation were uncovered, which explained the patient's compromised airways. Had this information been available prior to the scheduled operation, it would have indicated awake intubation with a local anaesthesia of the oropharynx and appropriate sedation of the patient.

Learning points: The CICO protocol was effective to manage an unanticipated difficult airway. The patient was resuscitated with the use of a microlaryngeal endotracheal tube of the 3rd generation laryngeal mask, placed on the fibrescope.The patient's previous and current medical condition is of vital importance for the pre-operative anaesthetic assessment.Specific questioning during the pre-operative anaesthetic interview could detect events that seem to be insignificant to the patient but are significant for a diagnostic intervention in a new situation.

Abstract
Measuring and comparing clinical productivity of individual anesthesiologists is confounded by anesthesiologist-independent factors, including facility-specific factors (case duration, anesthetizing site utilization, type of surgical procedure, and non-operating room locations), staffing ratio, number of calls, and percentage of clinical time providing anesthesia. Further, because anesthesia care is billed with different units than relative value units, comparing work with other types of clinical care is difficult. Finally, anesthesia staffing needs are not based on productivity measurements but primarily the number and hours of operation of anesthetizing sites. The intent of this review is to help anesthesiologists, anesthesiology leaders, and facility leaders understand the limitations of anesthesia unit productivity as a comparative metric of work, how this metric often devalues actual work, and the impact of organizational differences, staffing models and coverage requirements, and effectiveness of surgical case load management on both individual and group productivity.

Abstract
Prevention of arterial oxygen desaturation during anaesthesia with high-flow nasal oxygen (HFNO) has gained greater acceptance for a widening range of procedures. However, during HFNO use there remains the potential for development of significant anaesthesia-associated apnoea or hypoventilation and the possibility of hypercarbia, with harmful cardiovascular or neurological sequelae. The aim of this study was to determine whether any HFNO-related hypercarbia adverse incidents had been reported on webAIRS, an online database of adverse anaesthesia-related incidents. Two relevant reports were identified of complications due to marked hypercarbia during HFNO use to maintain oxygenation. In both reports, HFNO and total intravenous anaesthesia were used during endoscopic procedures through the upper airway. In both, the extent of hypoventilation went undetected during HFNO use. An ensuing cardiac arrest was reported in one report, ascribed to acute hypercarbia-induced exacerbation of the patient's pre-existing pulmonary hypertension. In the other report, hypercarbia led to a prolonged duration of decreased level of consciousness post procedure, requiring ventilatory support. During the search, an additional 11 reports of postoperative hypercarbia-associated sedation were identified, unrelated to HFNO. In these additional reports an extended duration of severe acute hypercarbia led to sedation or loss of consciousness, consistent with the known effects of hypercarbia on consciousness. These 13 reports highlight the potential dangers of unrecognised and untreated hypercarbia, even if adequate oxygenation is maintained.

Abstract
This narrative review summarizes research about prolonged times to tracheal extubation after general anesthesia with both intubation and extubation occurring in the operating room or other anesthetizing location where the anesthetic was performed. The literature search was current through May 2023 and included prolonged extubations defined either as >15 minutes or at least 15 minutes. The studies showed that prolonged times to extubation can be measured accurately, are associated with reintubations and respiratory treatments, are rated poorly by anesthesiologists, are treated with flumazenil and naloxone, are associated with impaired operating room workflow, are associated with longer operating room times, are associated with tardiness of starts of to-follow cases and surgeons, and are associated with longer duration workdays. When observing prolonged extubations among all patients receiving general anesthesia, covariates accounting for most prolonged extubations are characteristics of the surgery, positioning, and anesthesia provider's familiarity with the surgeon. Anesthetic drugs and delivery systems routinely achieve substantial differences in the incidences of prolonged extubations. Occasional claims made that anesthesia drugs have unimportant differences in recovery times, based on medians and means of extubation times, are misleading, because benefits of different anesthetics are achieved principally by reducing the variability in extubation times, specifically by decreasing the incidence of extubation times sufficiently long to have economic impact (ie, the prolonged extubations). Collectively, the results show that when investigators in anesthesia pharmacology quantify the rate of patient recovery from general anesthesia, the incidence of prolonged times to tracheal extubation should be included as a study end point.

Abstract
Purpose: In the context of the current comfort medicine and enhanced recovery after surgery, there is a demand for a new anesthesia method to reduce adverse reactions and accelerate recovery after surgery. This randomized controlled trial aimed to compare the efficacy and safety between opioid-free anesthesia (OFA) combined with ultrasound-guided intermediate cervical plexus block (ICPB) and opioid-based anesthesia in patients after thyroid surgery.

Methods: In this study, 75 patients scheduled for thyroid surgery under general anesthesia were randomly allocated into two groups. The primary outcome included the incidence of nausea within 24 h after surgery. The main secondary outcomes included the incidence of vomiting and the visual analog score (VAS) scores within 24 h after surgery as well as the quality of recovery 40 questionnaires (QoR-40) scores 24 h after surgery.

Results: In the OFA group, the incidence of postoperative nausea was 6.1%, compared to 39.4% in the control group (p = 0.001). No patient presented with postoperative vomiting in the OFA group, while 15.2% of patients suffered from postoperative vomiting in the control group (p = 0.063). The VAS scores of patients in the postanesthetic care unit (PACU) and 2 h, 4 h, and 6 h after surgery were lower in the OFA group, and the difference is statistically significant. Besides, the VAS scores of patients at rest (p = 1.000) and during swallowing (p = 1.000) 24 h after surgery were comparable.

Conclusion: Compared with opioid-based anesthesia, the OFA combined with the ultrasound-guided ICPB can better improve patients' postoperative recovery, reduce nausea, and decrease pain scores.

Trial registration: Chinese Clinical Trial Regisrty, ChiCTR2200056344, https://www.chictr.org.cn.

Keywords: Intermediate cervical plexus block; Nausea and vomiting; Opioid-free anesthesia; Thyroid surgery; s-Ketamine.

Abstract
Background: Anesthesiologists require an understanding of their patients' outcomes to evaluate their performance and improve their practice. Traditionally, anesthesiologists had limited information about their surgical outpatients' outcomes due to minimal contact post discharge. Leveraging digital health innovations for analyzing personal and population outcomes may improve perioperative care. BC Children's Hospital's postoperative follow-up registry for outpatient surgeries collects short-term outcomes such as pain, nausea, and vomiting. Yet, these data were previously not available to anesthesiologists.

Objective: This quality improvement study aimed to visualize postoperative outcome data to allow anesthesiologists to reflect on their care and compare their performance with their peers.

Methods: The postoperative follow-up registry contains nurse-reported postoperative outcomes, including opioid and antiemetic administration in the postanesthetic care unit (PACU), and family-reported outcomes, including pain, nausea, and vomiting, within 24 hours post discharge. Dashboards were iteratively co-designed with 5 anesthesiologists, and a department-wide usability survey gathered anesthesiologists' feedback on the dashboards, allowing further design improvements. A final dashboard version has been deployed, with data updated weekly.

Results: The dashboard contains three sections: (1) 24-hour outcomes, (2) PACU outcomes, and (3) a practice profile containing individual anesthesiologist's case mix, grouped by age groups, sex, and surgical service. At the time of evaluation, the dashboard included 24-hour data from 7877 cases collected from September 2020 to February 2023 and PACU data from 8716 cases collected from April 2021 to February 2023. The co-design process and usability evaluation indicated that anesthesiologists preferred simpler designs for data summaries but also required the ability to explore details of specific outcomes and cases if needed. Anesthesiologists considered security and confidentiality to be key features of the design and most deemed the dashboard information useful and potentially beneficial for their practice.

Conclusions: We designed and deployed a dynamic, personalized dashboard for anesthesiologists to review their outpatients' short-term postoperative outcomes. This dashboard facilitates personal reflection on individual practice in the context of peer and departmental performance and, hence, the opportunity to evaluate iterative practice changes. Further work is required to establish their effect on improving individual and department performance and patient outcomes.

Abstract
Purpose of review: This review article explores the application of multimodal anaesthesia in general anaesthesia, particularly in conjunction with locoregional anaesthesia, specifically focusing on the importance of EEG monitoring. We provide an evidence-based guide for implementing multimodal anaesthesia, encompassing drug combinations, dosages, and EEG monitoring techniques, to ensure reliable intraoperative anaesthesia while minimizing adverse effects and improving patient outcomes.

Recent findings: Opioid-free and multimodal general anaesthesia have significantly reduced opioid addiction and chronic postoperative pain. However, the evidence supporting the effectiveness of these approaches is limited. This review attempts to integrate research from broader neuroscientific fields to generate new clinical hypotheses. It discusses the correlation between high-dose intraoperative opioids and increased postoperative opioid consumption and their impact on pain indices and readmission rates. Additionally, it explores the relationship between multimodal anaesthesia and pain processing models and investigates the potential effects of nonpharmacological interventions on preoperative anxiety and postoperative pain.

Summary: The integration of EEG monitoring is crucial for guiding adequate multimodal anaesthesia and preventing excessive anaesthesia dosing. Furthermore, the review investigates the impact of combining regional and opioid-sparing general anaesthesia on perioperative EEG readings and anaesthetic depth. The findings have significant implications for clinical practice in optimizing multimodal anaesthesia techniques (Supplementary Digital Content 1: Video Abstract, http://links.lww.com/COAN/A96).

Abstract
Background: Whether volatile anesthetic solubility affects postanesthesia recovery time in clinical practice is unclear. We investigated the association among 3 volatile agents and 2 clinically relevant outcomes-postanesthesia care unit (PACU) recovery time (time from PACU admission to fulfillment of discharge criteria) and oversedation (Richmond Agitation-Sedation Scale score ≤-3)-as a potential contributor to delaying PACU discharge. The volatile agents studied were isoflurane, desflurane, and sevoflurane. We hypothesized that increased solubility of the volatile agent (isoflurane versus desflurane or sevoflurane) would be associated with longer PACU recovery time and higher rates of oversedation.

Methods: This retrospective observational study included adults (≥18 years) who underwent surgical procedures under general anesthesia with a volatile agent and were admitted to the PACU from May 5, 2018, to December 31, 2020. The primary outcome was PACU recovery time, and the secondary outcome was oversedation. PACU recovery time was log-transformed and analyzed with linear regression. Oversedation was analyzed by using logistic regression. To account for potential confounding, inverse probability of treatment weighting (IPTW) was used. Pairwise comparisons of the 3 agents were performed, with P < .017 (Bonferroni-adjusted) considered significant.

Results: Of 47,847 patients included, 11,817 (24.7%) received isoflurane, 11,286 (23.6%) received desflurane, and 24,744 (51.7%) received sevoflurane. Sevoflurane had an estimated 4% shorter PACU recovery time (IPTW-adjusted median [interquartile range {IQR}], 61 [42-89] minutes) than isoflurane (64 [44-92] minutes) (ratio of geometric means [98.3% confidence interval {CI}], 0.96 [0.95-0.98]; P < .001). Differences in PACU recovery time between desflurane and the other agents were not significant. The IPTW-adjusted frequency of oversedation was 8.8% for desflurane, 12.2% for sevoflurane, and 16.7% for isoflurane; all pairwise comparisons were observed to be significant (odds ratio [98.3% CI], 0.70 [0.62-0.79] for desflurane versus sevoflurane, 0.48 [0.42-0.55] for desflurane vs isoflurane, and 0.69 [0.63-0.76] for sevoflurane versus isoflurane; all P < .001). Although oversedated patients had longer PACU recovery time, differences in the oversedation rate across agents did not result in meaningful differences in time to PACU recovery.

Conclusions: In clinical practice, only small, clinically unimportant differences in PACU recovery time were observed between the volatile anesthetics. Although oversedation was associated with increased PACU recovery time, differences in the rate of oversedation among agents were insufficient to produce meaningful differences in overall PACU recovery time across the 3 volatile agents. Practical attempts to decrease PACU recovery time should address factors other than volatile agent selection.

Abstract
Background: Sevoflurane and desflurane are halogenated hydrocarbons with global warming potential. We examined the maximum potential benefit assuming 100% efficiency of waste gas capture technology used in operating rooms and recovery locations.

Methods: We performed computer simulations of adult patients using the default settings of the Gas Man software program, including the desflurane vaporizer setting of 9% and the sevoflurane vaporizer setting of 3.7%. We performed 21 simulations with desflurane and 21 simulations with sevoflurane, the count of 21 = 1 simulation with 0-hour maintenance + (1, 2, 3, 4, or 5 hours of maintenance) × (0.5, 1, 2, or 4 L per minute fresh gas flow during maintenance).

Results: (1) A completely efficient gas capture system could recover a substantive amount of agent even when the case is managed with low flows. All simulations had at least 22 mL agent recovered per case, considerably greater than the 12 mL that we considered the minimum volume of economic and environmental importance. (2) All 42 simulations had at least 73% recovery of the total agent administered, considerably greater than the median 52% recovery measured during an experimental study with one gas capture technology and desflurane. (3) The maximum percentage desflurane (or sevoflurane) that could be captured decreased substantively with progressively longer duration anesthetics for low-flow anesthetics but not for higher-flow anesthetics. However, for all 8 combinations of drug and liters per minute simulated, there was a substantively greater recovery in milliliters of agent for longer duration anesthetics. In other words, if gas capture could be near perfectly efficient, it would have greater utility per case for longer duration anesthetics. (4) Even using a 100% efficient gas capture process, at most 6 mL liquid desflurane or 3 mL sevoflurane per case would be exhaled during the patient's stay in the postanesthesia care unit. Therefore, the volume of agent exhaled during the first 1 hour postoperatively is not a substantial amount from an environmental and economic perspective to warrant consideration of agent capture by having all these patients in the postanesthesia care unit, or equivalent locations, using the specialized anesthetic gas scavenging masks with access to the hospital scavenging system at each bed.

Conclusions: Simulations with Gas Man show a strong rationale based on agent uptake and distribution for using volatile anesthetic agent capture in operating rooms if the technology can be highly efficient at volatile agent recovery.

Abstract
Jet injection is a drug delivery system without a needle. A compressed liquid drug formulation pierces the skin, depositing the drug into the subcutaneous or intramuscular tissues. We investigated the pharmacokinetics and patient experience of dexmedetomidine administered using jet injection in six healthy adult study participants. This needleless jet injection device was used to administer dexmedetomidine 0.5 μg/kg to the subcutaneous tissues overlying the deltoid muscle. Serum concentrations of dexmedetomidine were assayed at approximately 5 minutes, 15 minutes, 30 minutes, 1 hour and 4 hours after administration. Pharmacokinetic interrogation of concentration time profiles estimated an absorption half time for jet-injected dexmedetomidine of 21 minutes (coefficient of variation 69.4%) with a relative bioavailability assumed unity. In our samples the measured median peak (range) concentration was 0.164 μg/l (0.011-0.325 μg/l), observed in the sample taken at a median (range) of 13.5 minutes (11-30 minutes). The Richmond agitation sedation scale was used to assess the sedative effect, and scored 0 (alert and calm) or -1 (drowsy) in all participants. Five of the six participants stated they would prefer jet injection to needle injection in the future and one had no preference. The findings suggest that the use of a larger dose (>2 μg/kg) would be required to achieve the clinically relevant target concentration of 1 μg/l necessary to achieve deeper sedation (Richmond agitation sedation scale ≤3).

Abstract
Purpose: Memsorb™ is a novel device for carbon dioxide (CO2) removal from anesthesia circuits via a semipermeable polymeric membrane. We evaluated the performance of the memsorb device for the removal of CO2 in an Aisys™ CS2 machine and compared it with a standard chemical granulate absorber (CGA) using a high-fidelity lung simulator.

Methods: We used an in vitro lung simulator (DUCt) to control CO2 release by imitating alveolar gas exchange. The ventilator settings were identical for all measurements. The fresh gas flow (FGF) was randomized to either 0.5 L·min-1 or 2 L·min-1, completing three trials for each FGF for either memsorb or CGA. The EtCO2 and FICO2 levels were recorded for 30 min in each setting.

Results: EtCO2 was comparable between the groups with 2 L·min-1 FGF over the observation period. FICO2 was significantly higher in the memsorb group during the trial (2 L·min-1; 3.9 mm Hg; 95% CI, 4.4 to 3.3; P < 0.001). EtCO2 with 0.5 L·min-1 FGF was higher with memsorb than with CGA over the observation period (3.7 mm Hg; 95% CI, 2.7 to 4.7; P = 0.004). With 0.5 L·min-1 FGF, FICO2 was significantly higher in the memsorb group compared with CGA over the whole observation period (6 mm Hg; 95% CI, 6.4 to 5.5; P < 0.001).

Discussion: CO2 was successfully removed from the anesthesia circuit. FICO2 was significantly higher with memsorb throughout the observation period. Nevertheless, the clinical impact of these observations remains unclear. Further clinical trials are required to determine the utility of the novel device.

Keywords: anesthetics; carbon dioxide absorbent; intubation; mechanical ventilation; tidal volume.

Abstract
Purpose: It has been reported that cerebral oxygen saturation (rSO2) measured by near infrared spectroscopy is low in dialysis patients. We compared the rSO2 values of dialysis patients before living donor kidney transplantation and their donors as controls by using three spectroscopes that utilize different principals, the INVOS 5100C (spatially resolved spectroscopy), FORE-SIGHT ELITE (modified Beer-Lambert law) and tNIRS-1 (time-resolved spectroscopy).

Methods: Before induction of anesthesia, the sensors of one of the three spectroscopes were placed on the forehead and rSO2 values were recorded followed by the same measurement using the other two spectroscopes. The primary objective was to compare the rSO2 values of the dialysis patients and controls using the three spectroscopes by the unpaired t test. Then we compared the rSO2 values among the spectroscopes in both dialysis patients and controls by one-way ANOVA. Finally, we examined the relations between the rSO2 values and the physiological values by using the Pearson correlation coefficient.

Results: Fifteen pairs of dialysis patients and controls were studied. With the INVOS 5100 C, the values of the dialysis patients (59.7 ± 9.7% (mean ± standard deviation) were 13% lower than those of the controls (73.3 ± 6.9%) (P < 0.01). With the tNIRS-1, the values were 57.8 ± 4.8% in the dialysis patients and 63.3 ± 3.5% in the controls (P < 0.01). Almost no differences were observed with the FORE-SIGHT ELITE (71.6 ± 4.9% [dialysis patients] vs. 70.8 ± 4.3% [Controls]) (P = 0.62). Among the spectroscopes, the values were significantly different in both dialysis patients and controls. For the INVOS 5100C and tNIRS-1, correlation coefficients between rSO2 values and blood Hb and serum Alb were more than 0.5.

Conclusions: The rSO2 values for comparisons between the dialysis patients and the controls were different according to differences of the principles of the near infrared spectroscopes. In the INVOS 5100C and tNIRS-1, rSO2 values may be related to blood Hb and serum Alb.

Keywords: Cerebral oxygenation; Dialysis; Near infrared spectroscopy.

Abstract
The aging population and the obesity epidemic have led to an increased rate of joint arthroplasty procedures, specifically total knee arthroplasty and total hip arthroplasty. These surgeries are associated with increased hospital length of stay and, consequently, higher costs. Despite the benefits of outpatient surgery, only a small percentage of total joint arthroplasties (TJAs) are done in this manner. We reviewed the most up-to-date trends for outpatient TJA and discussed essential factors for a successful outpatient program, including the proper patient selection process and best available anesthetic and analgesic options, along with their risks and benefits. Risk stratification tools, such as the Outpatient Arthroplasty Risk Assessment, are helpful for predicting outcomes regarding outpatient TJA, and neuraxial anesthesia should be considered to minimize complications and facilitate early discharge. A multimodal analgesia regimen could be effective for pain management in outpatient TJA, and the currently recommended peripheral nerve blocks for total hip arthroplasty and total knee arthroplasty are the fascia iliaca compartment block and adductor canal block, respectively. However, blocks should be carefully considered for outpatient procedures. Enhanced recovery after surgery (ERAS) protocols help to guide perioperative care teams and allow for improved patient recovery, decreased length of stay, and increased patient satisfaction.

Abstract
Background: Worldwide, there is an increasing trend of performing more complex operations in a day care setting, usually driven by economic considerations. Provision of appropriate pain relief is still inadequate in this setting. Poor pain control and adverse effects of opioids provided for pain control are common reasons for readmission, with human and economic consequences. The aim of this review was to develop evidence-based protocol for pain management of day surgery in a resource limited setting.

Method: After formulating the key questions, scope, and eligibility criteria for the articles to be included, advanced search strategy of electronic sources from data bases and websites was conducted. Screening of literatures was conducted with proper appraisal checklist. This review was reported in accordance with preferred reporting items for systematic reviews and meta-analysis (PRISMA) 2020 statement.

Results: A total of 333 articles were identified from data bases and websites using an electronic search. 45 articles were removed for duplication and 87 studies were excluded after reviewing titles and abstracts. At the screening stage, 73 articles were retrieved and evaluated for eligibility. Finally, 40 studies met the eligibility criteria and were included in this systematic review.

Conclusion: Day surgery encourages patients to mobilize soon after surgery and empowers them to manage their own pain. Thus, preoperative patient education and high-quality perioperative pain management are paramount. With increasing healthcare demands for more day-case procedures, multi-modal analgesic techniques in the perioperative period with good extension of analgesia into the postoperative discharge period are essential.

Abstract
Background: Suggested anaesthetic dose ranges do not differ by sex, likely because of limited studies comparing sexes. Our objective was to systematically synthesise studies with outcomes of unintended anaesthesia awareness under anaesthesia, intraoperative connected consciousness, time to emergence from anaesthesia, and dosing to achieve adequate depth of anaesthesia, and to compare between females and males.

Methods: Studies were identified from MEDLINE, Embase, and the Cochrane library databases until August 2, 2022. Controlled clinical trials (randomised/non-randomised) and prospective cohort studies that reported outcomes by sex were included. Results were synthesised by random effects meta-analysis where possible, or narrative form.

Results: Of the 19 749 studies identified, 64 (98 243 participants; 53 143 females and 45 100 males) were eligible for inclusion, and 44 citations contributed to meta-analysis. Females had a higher incidence of awareness with postoperative recall (33 studies, odds ratio 1.38, 95% confidence interval [CI] 1.09-1.75) and connected consciousness during anaesthesia (three studies, OR 2.09, 95% CI 1.04-4.23) than males. Time to emergence was faster in females, including time to eye-opening (10 studies, mean difference -2.28 min, 95% CI -3.58 to -0.98), and time to response to command (six studies, mean difference -2.84 min, 95% CI -4.07 to -1.62). Data on depth of anaesthesia were heterogenous, limiting synthesis to a qualitative review which did not identify sex differences.

Conclusions: Female sex was associated with a greater incidence of awareness under general anaesthesia, and faster emergence from anaesthesia. These data suggest reappraisal of anaesthetic care, including whether similar drug dosing for females and males represents best care.

Abstract
Background: Pacific Island Countries (PICs) face unique challenges in providing surgical care. We assessed the surgical care capacity of five PICs to inform the development of National Surgical, Obstetric and Anaesthesia Plans (NSOAP).

Methods: We conducted a cross-sectional survey of 26 facilities in Fiji, Tonga, Vanuatu, Cook Islands, and Palau using the World Health Organization - Program in Global Surgery and Social Change Surgical Assessment Tool.

Findings: Eight referral and 18 first-level hospitals containing 39 functioning operating theatres, 41 post-anaesthesia care beds, and 44 intensive care unit beds served a population of 1,321,000 across the five countries. Most facilities had uninterrupted access to electricity, water, internet, and oxygen. However, CT was only available in 2/8 referral hospitals, MRI in 1/8, and timely blood transfusions in 4/8. The surgical, obstetric, and anaesthetist specialist density per 100,000 people was the highest in Palau (49.7), followed by Cook Islands (22.9), Tonga (9.9), Fiji (7.1), and Vanuatu (5.0). There were four radiologists and 3.5 pathologists across the five countries. Surgical volume per 100,000 people was the lowest in Vanuatu (860), followed by Fiji (2,247), Tonga (2,864), Cook Islands (6,747), and Palau (8,606). The in-hospital peri-operative mortality rate (POMR) was prospectively monitored in Tonga and Cook Islands but retrospectively measured in other countries. POMR was below 1% in all five countries.

Interpretation: Whilst PICs share common challenges in providing specialised tertiary services, there is substantial diversity between the countries. Strategies to strengthen surgical systems should incorporate both local contextualisation within each PIC and regional collaboration between PICs.

Abstract
Surgical, obstetric, and anaesthesia care saves lives, prevents disability, promotes economic prosperity, and is a fundamental human right. Session two of the three-part virtual meeting series on Strategic Planning to Improve Surgical, Obstetric, Anaesthesia, and Trauma Care in the Asia-Pacific Region discussed financing strategies for surgical care. During this session, participants made a robust case for investing in surgical care given its cost-effectiveness, macroeconomic benefits, and contribution to health security and pandemic preparedness. Funding for surgical system strengthening could arise from both domestic and international sources. Numerous strategies are available for mobilising funding for surgical care, including conducive macroeconomic growth, reprioritisation of health within government budgets, sector-specific domestic revenue, international financing, improving the effectiveness and efficiency of health budgets, and innovative financing. A wide range of funders recognised the importance of investing in surgical care and shared their currently funded projects in surgical, obstetric, anaesthesia, and trauma care as well as their funding priorities. Advocacy efforts to mobilise funding for surgical care to align with the existing funder priorities, such as primary health care, maternal and child health, health security, and the COVID-19 pandemic. Although the COVID-19 pandemic has constricted the fiscal space for surgical care, it has also brought unprecedented attention to health. Short-term investment in critical care, medical oxygen, and infection prevention and control as a part of the COVID-19 response must be leveraged to generate sustained strengthening of surgical systems beyond the pandemic.

Abstract
Postoperative systemic inflammation is strongly associated with surgical outcomes, but its relationship with patient-centred outcomes is largely unknown. Detection of excessive inflammation and patient and surgical factors associated with adverse patient-centred outcomes should inform preventative treatment options to be evaluated in clinical trials and current clinical care. This retrospective cohort study analysed prospectively collected data from 3000 high-risk, elective, major abdominal surgery patients in the restrictive vs. liberal fluid therapy for major abdominal surgery (RELIEF) trial from 47 centres in seven countries from May 2013 to September 2016. The co-primary endpoints were persistent disability or death up to 90 days after surgery, and quality of recovery using a 15-item quality of recovery score at days 3 and 30. Secondary endpoints included: 90-day and 1-year all-cause mortality; septic complications; acute kidney injury; unplanned admission to intensive care/high dependency unit; and total intensive care unit and hospital stays. Patients were assigned into quartiles of maximum postoperative C-reactive protein concentration up to day 3, after multiple imputations of missing values. The lowest (reference) group, quartile 1, C-reactive protein ≤ 85 mg.l-1 , was compared with three inflammation groups: quartile 2 > 85 mg.l-1 to 140 mg.l-1 ; quartile 3 > 140 mg.l-1 to 200 mg.l-1 ; and quartile 4 > 200 mg.l-1 to 587 mg.l-1 . Greater postoperative systemic inflammation had a higher adjusted risk ratio (95%CI) of persistent disability or death up to 90 days after surgery, quartile 4 vs. quartile 1 being 1.76 (1.31-2.36), p < 0.001. Increased inflammation was associated with increasing decline in risk-adjusted estimated medians (95%CI) for quality of recovery, the quartile 4 to quartile 1 difference being -14.4 (-17.38 to -10.71), p < 0.001 on day 3, and -5.94 (-8.92 to -2.95), p < 0.001 on day 30. Marked postoperative systemic inflammation was associated with increased risk of complications, poor quality of recovery and persistent disability or death up to 90 days after surgery

Abstract
Objective: To compare the effects of three types of ultrasound-guided nerve blocks on post-operative recovery quality in patients undergoing modified radical mastectomy for unilateral breast cancer.

Methods: In this randomized double-blinded trial (chictr.org.cn, ChiCTR2200059428), 150 female patients were equally assigned to S group (serratus anterior plane block, SAPB) group, P group (paravertebral block, PVB) or ST group (serratus anterior combined with transverse thoracic muscle plane blocks, SA-TTMPB). The primary outcome was QoR-15 at five time points after surgery. Secondary outcomes were pain scores, time of first rescue analgesic and chronic pain incidence at 3 months.

Results: The QoR-15 total score of S group at 24 h, 48 h, 72 h and 7 days post-surgery was significantly lower in groups P and ST, while there was no significant difference between groups P and ST (S vs. P vs. ST, 100.29 ± 6.20 vs. 108.51 ± 7.46 vs. 106.46 ± 6.95; 105.59 ± 6.18 vs. 113.06 ± 7.44 vs. 111.22 ± 6.56; 112.51 ± 6.32 vs. 119.88 ± 6.44 vs. 117.62 ± 6.09; 123.00 ± 5.78 vs. 128.86 ± 5.96 vs. 126.92 ± 5.72, p < 0.05). The dynamic and rest NRS scores at 6 and 12 h post-surgery were significantly higher in group S than in groups P and ST.

Conclusion: Serratus anterior plane block combined with transverse thoracic muscle plane block and paravertebral block both have better effects than serratus anterior plane block alone in improving patients' early post-operative recovery quality, and also have an advantage in improving early post-operative pain.

Abstract
Long QT syndrome (LQTS) is characterised by QT interval prolongation and ventricular arrhythmia, leading to sudden cardiac death. Patients with acquired or congenital LQTS pose special challenges to anaesthetists perioperatively due to the risk of developing life-threatening arrhythmia. A variety of medications, including commonly used volatile anaesthetic agents are known to prolong QT interval and there has been growing evidence of using total intravenous anaesthesia (TIVA) instead of volatile agents for such patients. This is a case report of a 30-year-old patient with congenital LQTS and subcutaneous implantable cardioverter defibrillator (SICD) in situ who underwent laparoscopic cholecystectomy and endoscopic retrograde cholangiopancreatography (ERCP) under TIVA safely within two months. There were no arrhythmic events observed perioperatively. This case highlights the importance of comprehensive planning and meticulous preparation to avoid all possible QT-prolonging conditions during the perioperative period, especially in patients with acquired or congenital LQTS.

Abstract
Background: Regional anaesthesia has the benefit of reducing the need for systemic analgesia and therefore, potentially reducing undesired side effects. With the end of the sensory nerve block however, many patients report severe pain that requires therapy with opioids and often compromise the initial opioid sparing effect. This study aimed to characterise the postoperative pain profile and the phenomenon of rebound pain after axillary brachial plexus anaesthesia (RA) compared to general anaesthesia (GA).

Design: Single-centre observational, stratified cohort study.

Setting: The study was conducted at University Hospital Marburg from May 2020 until September 2022.

Participants: One hundred thirty-two patients receiving elective hand and forearm surgery were enrolled in this study.

Interventions: Group RA received ultrasound-guided brachial plexus anaesthesia via the axillary approach with 30 mL of prilocaine 1% and 10 mL ropivacaine 0.2%. Group GA received balanced or total intravenous general anaesthesia.

Main outcome measures: Primary endpoint were integrated pain scores (IPS) within 24 h postoperatively. Secondary endpoints were pain scores (NRS 0-10), morphine equivalents, patient satisfaction, quality of recovery and opioid-related side effects.

Results: One hundred thirty-two patients were analysed of which 66 patients received brachial plexus block and 66 patients received general anaesthesia. Following RA significantly lower IPS were seen directly after surgery (p < .001) and during the post-anaesthesia care unit interval (p < .001) but equalised after 3 h at the ward. No overshoot in pain scores or increased opioid consumption could be detected. Patient satisfaction and postoperative recovery were comparable between both groups.

Conclusion: The IPS and NRS was initially lower in the RA group, increased with fading of the block until equal to the GA group and equal thereafter. Although various definitions of rebound pain were met during this phase, the opioid sparing effect of regional anaesthesia was not counteracted by it. The incidence of episodes with uncontrolled, severe pain did not differ between groups. We found no clinical implications of rebound pain in this setting, since the RA group did not show higher pain scores than the GA group at any time point.

Trial registration: German Clinical Trials Register (DRKS00021764).

Keywords: brachial plexus block; peripheral nerve block; postoperative pain; rebound pain; regional anaesthesia.

Abstract
Purpose: Repeated exposure of infant rhesus macaques to sevoflurane induces neurotoxicity and is associated with neurocognitive impairment in later life. We aimed to investigate the effect of repeated sevoflurane exposure on the expression of proteins in the prefrontal cortex of infant rhesus macaques by proteomics.

Methods: Rhesus macaques were exposed to sevoflurane three times, on postnatal days 7, 21 and 35. Quantitative proteomics employing LC-MS with isobaric labeling (TMT10plex), western blotting, and transmission electron microscopy (TEM) were utilized in the studies.

Results: The results of a proteomics investigation of the brain revealed that the proteins that were differentially expressed in rhesus macaques after sevoflurane exposures were associated mainly with mitochondrial respiration. Following multiple sevoflurane exposures, the prefrontal cortices of rhesus macaques exhibited increases in NDUFA8 and COX IV protein levels, while no alterations in mitochondrial morphology were observed through TEM.

Conclusion: Multiple exposures to sevoflurane increased the mitochondrial protein levels in rhesus macaques.

Keywords: Anesthesia; Macaques; Mitochondria; Proteomic; Sevoflurane.

Abstract
Background: The decision about which type of general anesthetic to administer is typically made by the clinical team without patient engagement. This study examined patients' preferences, experiences, attitudes, beliefs, perceptions, and perceived social norms about anesthesia and about engaging in the decision regarding general anesthetic choice with their clinician.

Methods: We conducted a survey in the United States, sent to a panel of surgical patients through Qualtrics (Qualtrics, Provo, UT) from March 2022 through May 2022. Questions were developed based on the Theory of Planned Behavior and validated measures were used when available. A patient partner who had experienced both intravenous and inhaled anesthesia contributed to the development and refinement of the questions.

Results: A total of 806 patients who received general anesthesia for an elective procedure in the last five years completed the survey. 43% of respondents preferred a patient-led decision making role and 28% preferred to share decision making with their clinical team, yet only 7.8% reported being engaged in full shared decision making about the anesthesia they received. Intraoperative awareness, pain, nausea, vomiting and quickly returning to work and usual household activities were important to respondents. Waking up in the middle of surgery was the most commonly reported concern, despite this experience being reported only 8% of the time. Most patients (65%) who searched for information about general anesthesia noted that it took a lot of effort to find the information, and 53% agreed to feeling frustrated during the search.

Conclusions: Most patients prefer a patient-led or shared decision making process when it comes to their anesthetic care and want to be engaged in the decision. However, only a small percentage of patients reported being fully engaged in the decision. Further studies should inform future shared decision-making tools, informed consent materials, educational materials and framing of anesthetic choices for patients so that they are able to make a choice regarding the anesthetic they receive.

Abstract
There are immunological consequences to the method by which neutrophils undergo cell death. Neutrophil apoptosis, called silent death, leads to the resolution of inflammation, while NETosis deepens and prolongs the inflammatory response and is associated with a worse prognosis of severe infections, e.g., sepsis. Besides nociceptive inhibition, local anaesthetics modulate leukocyte functions, even at low, clinically relevant concentrations. There is currently no data on ropivacaine NETosis, and this study aimed to evaluate the impact of clinical concentrations of ropivacaine (0.0007, 0.007 and 1.4 mmol/L) and lidocaine (0.002, 0.02 and 4 mmol/L) on apoptosis and NETosis of adult peripheral blood neutrophils after 2 h of incubation. Neutrophil identification, apoptosis and NETosis were evaluated by flow cytometry using forward and side scatter characteristics and fluorescent labelling: CD15 for neutrophils identification; Annexin V and propidium iodide for apoptosis and citrullinated histone H3 and myeloperoxidase for NETosis. Lidocaine (4 mmol/L) and ropivacaine (1.4 mmol/L) induced early apoptosis in resting but not in stimulated neutrophils. Low doses of ropivacaine (0.0007 and 0.007 mmol/L) decreased the number of late apoptotic neutrophils, and the lowest dose slightly increased their viability. None of the drugs induced NETosis in resting neutrophils but decreased NETosis at clinical concentrations compared to PMA-stimulated 4 mM lidocaine, PMA-stimulated control, and 1.4 mM ropivacaine. The effect of lidocaine and ropivacaine on apoptosis and NETosis depended on neutrophil stimulation and drug concentrations. Ropivacaine tends to be cytoprotective at concentrations observed in plasma under local anaesthesia. Lidocaine enhanced NETosis at high concentration only in stimulated neutrophils. Thus, both drugs have the ability to change the course of inflammation.

Keywords: Apoptosis; Inflammation; Local anaesthetics; NETosis; Neutrophils.

Abstract
Accurately predicting anesthetic effects is essential for target-controlled infusion systems. The traditional (PK-PD) models for Bispectral index (BIS) prediction require manual selection of model parameters, which can be challenging in clinical settings. Recently proposed deep learning methods can only capture general trends and may not predict abrupt changes in BIS. To address these issues, we propose a transformer-based method for predicting the depth of anesthesia (DOA) using drug infusions of propofol and remifentanil. Our method employs long short-term memory (LSTM) and gate residual network (GRN) networks to improve the efficiency of feature fusion and applies an attention mechanism to discover the interactions between the drugs. We also use label distribution smoothing and reweighting losses to address data imbalance. Experimental results show that our proposed method outperforms traditional PK-PD models and previous deep learning methods, effectively predicting anesthetic depth under sudden and deep anesthesia conditions.

Abstract
Background: Although patients are commonly monitored for depth of anesthesia, it is unclear to what extent administration of intravenous anesthetic medications may affect calculated bispectral (BIS) index values under general anesthesia.

Methods: In a retrospective analysis of electronic anesthesia records from an academic medical center, we examined BIS index changes associated with 14 different intravenous medications, as administered in routine practice, during volatile-based anesthesia using a novel screening approach. Discrete-time windows were identified in which only a single drug bolus was administered, and subsequent changes in the BIS index, concentration of volatile anesthetic, and arterial pressure were analyzed. Our primary outcome was change in BIS index, following drug administration. Adjusted 95% confidence intervals were compared to predetermined thresholds for clinical significance. Secondary sensitivity analyses examined the same outcomes, with available data separated according to differences in baseline volatile anesthetic concentrations, doses of the administered medications, and length of time window.

Results: The study cohort was comprised of data from 20,170 distinct cases, 54.7% of patients were men, with a median age of 55. In the primary analysis, ketamine at a median dose of 20 mg was associated with a median (confidence limits) increase in BIS index of 3.8 (2.5-5.0). Midazolam (median dose 2 mg) was associated with a median decrease in BIS index of 3.0 (1.5-4.5). Neither of these drug administrations occurred during time periods associated with changes in volatile anesthetic concentration. Analysis for dexmedetomidine was confounded by concomitant decreases in volatile anesthetic concentration. No other medication analyzed, including propofol and common opioids, was associated with a significant change in BIS index. Secondary analyses revealed that similar BIS index changes occurred when midazolam and ketamine were administered at different volatile anesthetic concentrations and different doses, and these changes persisted 11 to 20 minutes postadministration.

Conclusions: Modest, but persistent changes in BIS index occurred following doses of ketamine (increase) and midazolam (decrease) during periods of stable volatile anesthetic administration.

Abstract
Importance: Accurate measurements of clinical workload are needed to inform health care policy. Existing methods for measuring clinical workload rely on surveys or time-motion studies, which are labor-intensive to collect and subject to biases.

Objective: To compare anesthesia clinical workload estimated from electronic health record (EHR) audit log data vs billed relative value units.

Design, setting, and participants: This cross-sectional study of anesthetic encounters occurring between August 26, 2019, and February 9, 2020, used data from 8 academic hospitals, community hospitals, and surgical centers across Missouri and Illinois. Clinicians who provided anesthetic services for at least 1 surgical encounter were included. Data were analyzed from January 2022 to January 2023.

Exposure: Anesthetic encounters associated with a surgical procedure were included. Encounters associated with labor analgesia and endoscopy were excluded.

Main outcomes and measures: For each encounter, EHR-derived clinical workload was estimated as the sum of all EHR actions recorded in the audit log by anesthesia clinicians who provided care. Billing-derived clinical workload was measured as the total number of units billed for the encounter. A linear mixed-effects model was used to estimate the relative contribution of patient complexity (American Society of Anesthesiology [ASA] physical status modifier), procedure complexity (ASA base unit value for the procedure), and anesthetic duration (time units) to EHR-derived and billing-derived workload. The resulting β coefficients were interpreted as the expected effect of a 1-unit change in each independent variable on the standardized workload outcome. The analysis plan was developed after the data were obtained.

Results: A total of 405 clinicians who provided anesthesia for 31 688 encounters were included in the study. A total of 8 288 132 audit log actions corresponding to 39 131 hours of EHR use were used to measure EHR-derived workload. The contributions of patient complexity, procedural complexity, and anesthesia duration to EHR-derived workload differed significantly from their contributions to billing-derived workload. The contribution of patient complexity toward EHR-derived workload (β = 0.162; 95% CI, 0.153-0.171) was more than 50% greater than its contribution toward billing-derived workload (β = 0.106; 95% CI, 0.097-0.116; P < .001). In contrast, the contribution of procedure complexity toward EHR-derived workload (β = 0.033; 95% CI, 0.031-0.035) was approximately one-third its contribution toward billing-derived workload (β = 0.106; 95% CI, 0.104-0.108; P < .001).

Conclusions and relevance: In this cross-sectional study of 8 hospitals, reimbursement for anesthesiology services overcompensated for procedural complexity and undercompensated for patient complexity. This method for measuring clinical workload could be used to improve reimbursement valuations for anesthesia and other specialties.

Abstract
Background and aims: Patients with traumatic brain injury (TBI) frequently require emergency surgery. There is a paucity of literature with regard to anesthetic requirements in these patients. The aim of the study was to compare the dose of propofol required for induction of anesthesia in patients with different grades of TBI.

Material and methods: This prospective, observational study included patients with mild, moderate, and severe grades of TBI undergoing emergency surgery within 48 h of injury. Bispectral Index (BIS) values were recorded using a bilateral BIS sensor. Anesthesia was induced with a target controlled infusion (TCI) pump. Once BIS reached 40, plasma (Cp) and effect-site (Ce) concentration and total dose of propofol required were noted from the TCI pump.

Results: Of the 96 patients recruited, 27, 36, and 33 patients belonged to mild, moderate, and severe TBI (sTBI) groups, respectively. The Ce of propofol in mild, moderate, and sTBI groups was 6 ± 0.9, 5.82 ± 0.98, and 4.48 ± 1.5 μg/mL (P < 0.001), and the dose of propofol required was 1.9 ± 0.2, 1.8 ± 0.4, 1.41 ± 0.5 mg/kg, respectively (P < 0.001). Baseline BIS on the injured side was 80 ± 7.8, 71 ± 9.4, 55 ± 11.6, and on the uninjured side was 89 ± 5.5, 81 ± 8.4, and 65 ± 12 in mild, moderate, and sTBI groups, respectively.

Conclusions: The requirement of propofol was reduced in patients with sTBI. The dose of propofol required for induction of anesthesia as determined using Ce was significantly lower only between sTBI and mild TBI and not between patients with sTBI and moderate TBI or between mild and moderate head injury. BIS values were significantly different between the groups (highest in mild TBI and lowest in sTBI) and between normal and injured sides within each group.

Keywords: Anesthesia induction; BIS; propofol; target-controlled infusion; traumatic brain injury.

Abstract
Electroencephalogram (EEG)-guided anesthesia is indispensable in modern operating rooms and has become established as the standard form of monitoring. Many anesthesiologists rely on processed EEG indices in the hope of averting anesthesia-related complications, such as intraoperative awareness, postoperative delirium and other cognitive complications in their patients. This educational review aims to provide information on the five most prevalent monitors used to guide depth of sedation during general anesthesia. This article elucidates the principles underpinning the application of these monitors where known, which are generally based on power in various EEG frequency bands and on the burst suppression pattern. Convinced that EEG-guided anesthesia has the potential of benefitting many surgical patients, it is felt that many basic principles and shortcomings of processed EEG indices need to be better understood in the clinical practice. After discussing the different monitors and clinically relevant data from the literature, the article gives a short practical guidance on how to critically interpret processed EEG information and troubleshooting of confounded indices in the context of clinical situations.

Abstract
Introduction: Proton beam therapy is an oncological treatment, argued to be an appropriate tumor irradiation technique for childhood solid tumors. Due to its duration and the need for immobility, many children require anesthesia for proton therapy sessions. As not many centers in the world provide this therapy, there is little published research about pediatric anesthesia for these cases, and the available data suggest a preference for intravenous anesthesia or combined intravenous and inhalation anesthesia. We conducted this study with the aim of describing and analyzing the inhalation anesthetic management of children undergoing proton therapy at our medical center, comparing our results with studies that have followed different anesthetic protocols.

Methods: We reviewed two major databases (Web of Science and Scopus) to find papers that had addressed, to date, anesthesia for pediatric proton therapy. To describe our anesthetic management, we included all pediatric patients treated with proton therapy under anesthesia in our center between June 2020 and August 2021. The characteristics of the patients, their diagnoses, treatments, airway management, drugs administered, duration of induction, and recovery from anesthesia, and adverse effects where all recorded. All anesthesiologists followed a strict anesthetic protocol based only on inhalational anesthesia with sevoflurane delivered via laryngeal mask airway.

Results: Of the total of 1082 papers found in Web of Science and Scopus on pediatric proton therapy, 11 have addressed its anesthetic management, using intravenous or combined intravenous and inhalation anesthesia. Between June 2020 and August 2021, 31 children were anesthetized in our center to receive proton therapy under inhalational anesthesia (total number of sessions: 873). The mean anesthesia induction time was 4.1 min (SD = 0.7, 95% CI [3.9, 4.4]). The mean anesthesia recovery time was 13.8 min (SD = 4.1, 95% CI [12.3, 15.3]). The percentage of non-serious adverse effects was 0.7% (Clopper-Pearson 95% CI [0.3, 1.5]). The percentage of serious adverse effects was 0.1% (Clopper-Pearson 95% CI [0, 0.6]), without statistically significant difference with other published works with different anesthetic approaches.

Conclusion: Inhalation anesthesia without any intravenous management for pediatric proton therapy is, in our experience, an effective technique with a complication rate similar to other anesthetic approaches.

Abstract
Objective: We aimed to compare the labor analgesia effects of nonpharmaceutical analgesia and pharmaceutical analgesia on parturient women.

Methods: One hundred and four parturient women with spontaneous births were selected and randomly divided into pharmaceutical and nonpharmaceutical analgesia groups. Before and after analgesia, the Visual Analogue Scale (VAS), parturient satisfaction with analgesia, serum pain stress factors (substance P [SP], neuropeptide Y [NPY], nerve growth factor [NGF], and prostaglandin E2 [PGE2]), duration of labor, vaginal bleeding at 2 h postpartum, postpartum urinary retention and dysuria incidence, Apgar score of 1 min and 5 min after birth, and neonatal cord blood gas analysis (pH, partial pressure of oxygen [PO2 ], partial pressure of carbon dioxide [PCO2 ], and lactate [Lac]) were compared in the two groups.

Results: VAS scores were lower and the analgesia satisfaction was higher in the pharmaceutical analgesia group than in the nonpharmaceutical analgesia group (all p < .05). Serum levels of SP, NPY, NGF, and PGE2 in the pharmaceutical analgesia group were lower than those in the nonpharmaceutical analgesia group (all p < .05). The first and second stages of labor were longer and the bleeding volume at 2 h postpartum was greater in the pharmaceutical analgesia group than those in the nonpharmaceutical analgesia group (all p < .05). Reduced Lac and PCO2 levels and increased PO2 level were found in the pharmaceutical analgesia group in comparison to the nonpharmaceutical analgesia group (all p < .05).

Conclusion: This study demonstrates that the analgesic effect and neonatal condition of the pharmaceutical analgesia are better than the nonpharmaceutical analgesia, but the labor duration and postpartum bleeding volume of the pharmaceutical analgesia are greater than those of the nonpharmaceutical analgesia.

Abstract
The global shortage of skilled anaesthesiologists, surgeons and obstetricians is a leading cause of high unmet surgical need. Although anaesthetic and surgical task-shifting are widely practiced to mitigate this barrier, little is known about their safety and efficacy. This systematic review seeks to highlight the existing evidence on the clinical outcomes of patients operated on by non-physicians or non-specialist physicians globally. Relevant articles were identified by searching four databases (MEDLINE, Embase, CINAHL, and Global Health) in all languages between 2008 and February 2022. Retrieved documents were screened against pre-specified inclusion and exclusion criteria and their qualities were appraised critically. Data were extracted by two independent reviewers and findings were synthesised narratively. In total, 40 studies have been included. Thirty-five focus on task-shifting for surgical and obstetric procedures, whereas four studies address anaesthetic task-shifting; one study covers both interventions. The majority are located in Sub-Saharan Africa and the United States. Seventy-five percent present perioperative mortality outcomes and 85% analyse morbidity measures. Evidence from low- and middle-income countries, which primarily concentrates on caesarean sections, hernia repairs, and surgical male circumcisions, points to the overall safety of non-surgeons. On the other hand, the literature on surgical task-shifting in high-income countries is limited to nine studies analysing tube thoracostomies, neurosurgical procedures, caesarean sections, male circumcisions, and basal cell carcinoma excisions. Finally, only five studies pertaining to anaesthetic task-shifting across all country settings answer the research question with conflicting results, making it difficult to draw conclusions on the quality of non-physician anaesthetic care. Overall, it appears that non-specialists can safely perform high-volume, low-complexity operations. Further research is needed to understand the implications of surgical task-shifting in high-income countries and to better assess the performance of non-specialist anaesthesia providers. Future studies must adopt randomised study designs and include long-term outcome measures to generate high quality evidence.

Abstract
Background: Open cranial vault reconstruction is the standard technique of craniosynostosis correction that may cause significant blood loss.

Objectives: The current study aimed at comparing the effect of tranexamic acid (TXA), controlled hypotension, and their combination on perioperative blood loss and transfusion requirement in craniosynostosis surgery.

Methods: The present randomized, double-blind clinical trial was conducted on 75 infants referred for craniosynostosis surgery during 2017 - 2018. Ten minutes before the start of surgery, 10 mg/kg of TXA was administered intravenously to patients in the first group (TXA group). In the second group, patients were subjected to the controlled hypotension anesthesia (CHA) using intravenous remifentanil 0.1 μ/kg (CHA group). In the third group, the patients underwent CHA similar to that of the second group, along with intravenous injection of 10 mg/kg of TXA (CHA-TXA group). Then, patients' mean arterial pressure (MAP), heart rate (HR), total blood loss, and transfusion volume were evaluated and recorded.

Results: The results of the present study revealed that although the changes in MAP and HR parameters over time (three hours after surgery) were significant in all three groups, the lowest decrease was observed in the CHA-TXA group (P-value < 0.05). In addition, the total perioperative blood loss in the CHA-TXA group with the mean of 181.20 ± 82.71 cc was significantly less than the total perioperative blood loss in the CHA and TXA groups with the means of 262.00 ± 104.04 cc and 212.80 ± 80.75 cc, respectively (P-value < 0.05). Moreover, the transfusion volume in the CHA-TXA group with the mean of 112.40 ± 53.50 cc was significantly lower than the transfusion volume in the CHA and TXA groups with the means of 174.00 ± 73.93 cc and 160.63 ± 59.35 cc, respectively (P-value < 0.05). In contrast, the total blood loss and transfusion volume were not significantly different between the CHA and TXA groups (P-value > 0.05).

Conclusions: According to the results of the present study, although the administration of TXA alone could effectively prevent blood loss and was associated with fewer transfusion requirements, the combination of this approach with hypotensive anesthesia resulted in more reduction in perioperative blood loss and transfusion volume as well as better hemodynamic stability.

Abstract
Background: In-office laryngological procedures became common alternatives to general anesthesia for biopsies, injection laryngoplasties, and laser procedures. The limiting step remains the laryngeal anesthesia whose quality can influence patients' and operators' comfort.

Methods: We propose to dye the lidocaine with methylene blue and do an instillation through a catheter introduced in the video-endoscope's operating channel, which permits a progressive anesthesia focused on the larynx, avoiding an unwanted pharyngeal anesthesia and any tracheal irritation.

Conclusion: Using blue-dyed lidocaine can help reduce the volume of anesthesia required for an office-based laryngology intervention, improving patients' and surgeon's comfort and reducing anesthesia's side effects.

Full citation:
Haddad R, Mattei A, Giovanni A. Local anesthesia with blue-dyed lidocaine for a better patient's tolerance during office-based laryngology procedures: how I do it [published online ahead of print, 2023 Jul 25]. Eur Arch Otorhinolaryngol. 2023;10.1007/s00405-023-08146-y.

Abstract
Background: Pressure-controlled face mask ventilation (PC-FMV) with positive end-expiratory pressure (PEEP) after apnoea following induction of general anaesthesia prolongs safe apnoea time and reduces atelectasis formation. However, depending on the set inspiratory pressure, a delayed confirmation of a patent airway might occur. We hypothesised that by lowering the peak inspiratory pressure (PIP) when using PC-FMV with PEEP, confirmation of a patent airway would not be delayed as studied by the first return of CO2 , compared with manual face mask ventilation (Manual FMV).

Methods: This was a single-centre, randomised controlled non-inferiority trial. Seventy adult patients scheduled for elective day-case surgery under general anaesthesia with body mass index between 18.5 and 29.9 kg m-2 , American Society of Anesthesiologists (ASA) classes I-III, and without anticipated difficult FMV, were included. Before the start of pre-oxygenation and induction of general anaesthesia, participants were randomly allocated to receive ventilation with either PC-FMV with PEEP, at a PIP of 11 and a PEEP of 6 cmH2 O or Manual FMV, with the adjustable pressure-limiting valve set at 11 cmH2 O. The primary outcome variable was the number of ventilatory attempts needed until confirmation of a patent airway, defined as the return of at least 1.3 kPa CO2.

Full citation:
Edmark L, Englund EK, Jonsson AS, Zilic AT, Cajander P, Östberg E. Pressure-controlled versus manual facemask ventilation for anaesthetic induction in adults: A randomised controlled non-inferiority trial [epub ahead of print, 2023 Jul 21]. Acta Anaesthesiol Scand. 2023;10.1111/aas.14308.

Abstract
Background: A high fresh gas flow of >5 L/minute is commonly used for emergence from inhalation anesthesia. In addition, a high fresh gas flow may have detrimental effects on climate change. However, no study has determined the optimal fresh gas flow for emergence from inhalation anesthesia. Therefore, we compared the effect of fresh gas flows of 5 L/minute and 10 L/minute on emergence time from sevoflurane anesthesia.

Methods: Patients who were scheduled for transurethral resection of bladder tumor were randomly assigned to receive fresh gas flows of 5 L/minute (group 5) or 10 L/minute (group 10) during emergence. Emergence time was defined as the time from discontinuation of sevoflurane to tracheal extubation. The primary outcome was the emergence time, and the secondary outcomes were the time to self-movement and the time to eye-opening.

Abstract
Purpose: The use of an endotracheal tube (ET) cuff filled with alkalized lidocaine (AL) can suppress ET-induced emergence phenomena, such as hypertension, tachycardia and coughing, and postoperative sore throat (POST) and hoarseness (PH). The efficacy of intracuff lidocaine may vary depending on the cuff shape, but there has been no study on the effects of a tapered cuff filled with AL. We examined whether intracuff AL suppresses ET-induced emergence phenomena, POST and PH.

Methods: Sixty-two patients were enrolled in this study and the patients were randomly allocated to a group in which the tapered cuff was filled with AL (Group AL) and a group in which the tapered cuff was filled with normal saline (Group S). The primary outcomes of this study were changes in mean blood pressure (MBP) and heart rate (HR) at extubation. MBP, HR and the number of coughs were recorded before and up to 10 min after extubation. The degree of POST and the incidences of POST and PH were recorded at 15 min, 2 h and 24 h after extubation.

Abstract
Purpose: Remimazolam, a newly synthesized ultrashort-acting benzodiazepine, has not been previously compared with sevoflurane with regard to postoperative nausea and vomiting (PONV). The aim of this study is to investigate the incidence of PONV between remimazolam and sevoflurane among patients undergoing artificial joint replacement surgery.

Methods: We conducted a retrospective analysis of the electronic medical records of patients who underwent artificial joint replacement surgery at Kobe City Medical Center General Hospital from 2020 to 2022, with a focus on comparing the incidence of PONV among those who received sevoflurane versus remimazolam anesthesia. To control for confounding factors, we employed a propensity score-matching technique to pair patients who received sevoflurane anesthesia with those who received remimazolam anesthesia.

There is conflicting information about the effect of vitamin C on brain oxygenation during anesthesia.
The current study was designed and performed to assess the effect of vitamin C infusion and brain oxygenation with cerebral oximetry on improving brain perfusion during general anesthesia in vascular surgery of diabetic patients.

In patients with severe aneurysmal subarachnoid hemorrhage (SAH) deep sedation is often used early in the course of the disease in order to control brain edema formation and thus intracranial hypertension. However, some patients do not reach an adequate sedation depth despite high doses of common intravenous sedatives. Balanced sedation protocols incorporating low-dose volatile isoflurane administration might improve insufficient sedation depth in these patients. This study retrospectively analyzed ICU patients with severe aneurysmal SAH who received isoflurane in addition to intravenous anesthetics in order to improve insufficient sedation depth. Routinely recorded data from neuromonitoring, laboratory and hemodynamic parameters were compared before and up to 6 days after initiation of isoflurane.

Keywords: Antiemetics; General anesthesia; Gravidity; Postoperative nausea and vomiting.

Keywords: HIV; anaesthesia; critical care; immunodeficiency.

Learning Objectives:
By reading this article, you should be able to:

• Describe the clinical assessment of fluid status and fluid responsiveness in children.
• Explain the clinical reasoning for the type and amount of i.v. fluids given to children during surgery.
• Detail the reasons and benefits for promoting clear oral fluid intake in children before surgery.

Abstract
Objectives: Clinical risk calculators (CRCs), such as NZRisk, are used daily by clinicians to guide clinical decisions and explain individual risk to patients. The utility and robustness of these tools depends on the methods used to create the underlying mathematical model, as well as the stability of that model in relation to changing clinical practice and patient populations over time. The later should be checked by temporal validation using external data. Few if any of the clinical prediction models in current clinical use have published temporal validation. Here, we use a large external dataset to temporally validate NZRisk; a perioperative risk prediction model used in the New Zealand population.

Methods: A sample of 1 976 362 adult non-cardiac surgical procedures collected over 15 years from the New Zealand Ministry of Health National Minimum Dataset, was used to temporally validate NZRisk. We divided the dataset into 15 single year cohorts and compared 13 of these to our NZRisk model (2 years used for the model building were excluded). We compared the area under the curve (AUC) value, calibration slope and intercept for each single year cohort, to the same values produced by the data used to create NZRisk, by fitting a random effects meta-regression with each year cohort acting as a separate study point. In addition, we used two-sided t-tests to compare each measure across the cohorts.

Results: The AUC values for the 30-day NZRisk model applied to our single year cohorts ranged from 0.918 to 0.940 (NZRisk AUC was 0.921). There were eight statistically different AUC values for the following years 2007-2009, 2016 and 2018-2021. The intercept values ranged from -0.004 to 0.007 and 7 years had statistically significant different intercepts during leave-one-out t-tests; 2007-2010, 2012, 2018 and 2021. The slope values ranged from 0.72 to 1.12 and 7 years had statistically significant different slopes during leave-one-out t-tests; 2010, 2011, 2017, 2018 and 2019-2021. The random effects meta-regression upheld our results related to AUC (0.54 (95% CI 0.40 to 0.99), I2 67.57 (95% CI 40.67 to 88.50), Cochran's Q<0.001) and slope (τ 0.14 (95% CI 0.01 to 0.23), I2 98.61 (95% CI 97.31 to 99.50), Cochran's Q<0.001) between year difference.

Conclusion: The NZRisk model shows differences in AUC and slope but not intercept values over time. The biggest differences were in the calibration slope. The models maintained excellent discrimination over time as shown by the AUC values. These findings suggest we update our model in the next 5 years. To our knowledge, this is the first temporal validation of a CRC in current use.

Keywords: anaesthesia; cancer metastasis; cancer recurrence; cancer surgery; onco-anaesthesia; postoperative analgesia; regional anaesthesia; surgery; total intravenous anaesthesia; volatile anaesthesia.

Keywords: discharge; general anesthesia; opioid; pain relief; postoperative nausea and vomiting; spinal anesthesia.

Keywords: antibiotic stewardship; health care-associated infections; managerial epidemiology; nonoperating room anesthesia.

Keywords: anxiety; arterial blood gas; emergency department; nocebo; pain; positive therapeutic communication; therapeutic communication.

Keywords: Europe-wide survey; anesthesiology; artificial intelligence; health care; intensive care; medical informatics; technology acceptance.

Keywords: Dexmedetomidine; Elderly; General anaesthesia; Haemodynamics; Hip replacement; Recovery.

Acute pain; Advanced pain procedure; Cancer; Chronic pain; Disparities; Diversity; Elderly; Ethnicity; Gender; Geography; Obstetric; Pediatric; Race; Rural; Socioeconomic; Veteran.

Keywords: anesthesia; meta-analysis; stroke.

Abstract
The future and sustainability of the anaesthetic workforce is a growing concern with a projected shortfall of 11,000 anaesthetists by 2040. The supply of anaesthetists able to provide safe anaesthesia care does not meet the rising demand of surgical waiting lists. In recent years, changes to recruitment and curricula for anaesthetic specialty training have resulted in significant bottlenecks to training progression, further compounding the deficit in the numbers of fully trained anaesthetists. A rapid expansion the Anaesthesia Associate (AA) workforce has been proposed as one of the solutions to this worsening gap. However, no robust analysis of the impact of the expansion in AA numbers on anaesthetists in training has been conducted. There remain a number of concerns regarding access to training experience, scope of supervision, out of hours workload, equity of pay and cost of training, as well as the impact on future numbers of anaesthetists in training. In order to help shape the future integration of this workforce, we surveyed current anaesthetists in training, asking about their experiences of working with AAs, and their perceptions of the future expansion and regulation of these associate professionals. Through an online survey, we collected both quantitative and qualitative data to give a thorough representation of anaesthetists in training experience. Our results confirm that the impact of AAs on training remains a polarising topic. A third of anaesthetists in training with prior experience of working with AAs reported a negative impact on their training experience. Factors mentioned included lack of case numbers, lack of access to learning and performing regional anaesthesia, and lack of clarity in lines of supervision. Of those with no prior experience working with AAs, there was a strong negative perception towards expansion of the workforce. A small proportion described a positive experience, indicating that with clear role definition, careful implementation along with co-operation, a positive experience in all departments could be achievable. Our findings suggest a need for increased consultation and communication with stakeholders in the anaesthesia workforce, including anaesthetists in training, to ensure smooth and safe integration of the AA workforce.

Keywords: complications; epilepsy; vagus nerve stimulator.

Keywords: Adverse effects; Hepatectomy; Morphine consumption; Pain scores; Propofol TIVA.

Abstract
The practice of anaesthetists relating to the administration of intraoperative oxygen has not been previously quantified in Australia and New Zealand. The optimal regimen of intraoperative oxygen administration to patients undergoing surgery under general anaesthesia is not known, and international recommendations for oxygen therapy are contradictory; the World Health Organization (WHO) recommend administering an intraoperative fraction of inspired oxygen of at least 0.8, while the World Federation of Societies of Anaesthesiologists, British Thoracic Society, and Thoracic Society of Australia and New Zealand recommend a more restrictive approach. We conducted a prospective observational study to describe the pattern of intraoperative oxygen administration among anaesthetists in Australia and New Zealand and, second, to determine the proportion of anaesthetists who administer intraoperative inspired oxygen in accordance with the WHO recommendations. We identified 150 anaesthetists from ten metropolitan hospitals in Australia and New Zealand and observed the patterns of intraoperative oxygen administration to American Society of Anesthesiologists physical status classification (ASA) 3 or 4 patients undergoing prolonged surgery under general anaesthesia. The median (interquartile range) intraoperative time-weighted mean fraction of inspired oxygen (FiO2) for all participants in the study was 0.47 (0.40-0.55). Three out of 150 anaesthetists (2%, 95% confidence interval 0.4 to 5.7) administered an average intraoperative FiO2 of at least 0.8. These findings indicate that most anaesthetists routinely administer an intermediate level of oxygen for ASA 3 or 4 adult patients undergoing prolonged surgery in Australia and New Zealand, rather than down-titrating inspired oxygen to a target pulse oximetry reading (SpO2) or administering liberal perioperative oxygen therapy in line with the current WHO recommendation.

Abstract
Introduction: Association between sugammadex and risk of postoperative nausea and vomiting remains unclear.

Evidence acquisition: We performed meta-analysis of randomized controlled trials with trial sequential analysis to compare sugammadex with neostigmine in adults receiving elective surgery under general anesthesia with postoperative extubation. Databases of MEDLINE, Embase, and Cochrane Central Register of Controlled Trials were searched from inception to April 15, 2022. Primary outcome was risk of postoperative nausea and vomiting after patients received sugammadex or neostigmine. Secondary outcomes were incidences of sugammadex-related complications.

Evidence synthesis: Meta-analysis of 40 trials with 5455 patients showed an overall lower risk of postoperative nausea and vomiting in the sugammadex group than in the neostigmine group (risk ratio: 0.85, 95% CI [0.76-0.94], heterogeneity I2=4%, P=0.002). Subgroup analyses demonstrated a lower risk of postoperative nausea and vomiting associated with sugammadex than with neostigmine: 1) in the postanesthesia care unit (risk ratio: 0.77, 95% CI [0.66-0.90], I2=8%, P=0.001) but not in wards; 2) under volatile anesthetics but not total intravenous anesthesia; 3) regardless of the administration of prophylactic antiemetics; and 4) when sugammadex was administered at 2 mg/kg but not 4 mg/kg. No major complications such as cardiac arrest or refractory bradycardia were noted and every patient achieved adequate neuromuscular recovery before extubation in all of the included trials. The overall quality of evidence was moderate.

Conclusions: Sugammadex was associated with a lower risk of postoperative nausea and vomiting compared with neostigmine immediately after surgery, especially for patients receiving volatile anesthetics regardless of the use of prophylactic antiemetics.

Abstract
This article addresses the issue of patient sleep during hospitalization, which the Society of Anesthesia and Sleep Medicine believes merits wider consideration by health authorities than it has received to date. Adequate sleep is fundamental to health and well-being, and insufficiencies in its duration, quality, or timing have adverse effects that are acutely evident. These include cardiovascular dysfunction, impaired ventilatory function, cognitive impairment, increased pain perception, psychomotor disturbance (including increased fall risk), psychological disturbance (including anxiety and depression), metabolic dysfunction (including increased insulin resistance and catabolic propensity), and immune dysfunction and proinflammatory effects (increasing infection risk and pain generation). All these changes negatively impact health status and are counterproductive to recovery from illness and operation. Hospitalization challenges sleep in a variety of ways. These challenges include environmental factors such as noise, bright light, and overnight awakenings for observations, interventions, and transfers; physiological factors such as pain, dyspnea, bowel or urinary dysfunction, or discomfort from therapeutic devices; psychological factors such as stress and anxiety; care-related factors including medications or medication withdrawal; and preexisting sleep disorders that may not be recognized or adequately managed. Many of these challenges appear readily addressable. The key to doing so is to give sleep greater priority, with attention directed at ensuring that patients' sleep needs are recognized and met, both within the hospital and beyond. Requirements include staff education, creation of protocols to enhance the prospect of sleep needs being addressed, and improvement in hospital design to mitigate environmental disturbances. Hospitals and health care providers have a duty to provide, to the greatest extent possible, appropriate preconditions for healing. Accumulating evidence suggests that these preconditions include adequate patient sleep duration and quality. The Society of Anesthesia and Sleep Medicine calls for systematic changes in the approach of hospital leadership and staff to this issue. Measures required include incorporation of optimization of patient sleep into the objectives of perioperative and general patient care guidelines. These steps should be complemented by further research into the impact of hospitalization on sleep, the effects of poor sleep on health outcomes after hospitalization, and assessment of interventions to improve it.

Perioperative arrhythmias are extremely common, usually transient and typically require no intervention. Persistent arrhythmias with associated haemodynamic instability may reflect an underlying pathological process. Indeed, the clinical scenario outlined of a patient with sepsis who develops rapid atrial fibrillation describes a situation that anaesthetists and intensivists frequently encounter. In some situations, the primary cause of the arrhythmia may be evident. However, in many cases the cause is multifactorial, relating to coexisting disease, acute physiological disturbance, medications or the surgical procedure itself (e.g. cardiac or thoracic surgery).

Abstract
Purpose: We aimed to describe the current literature concerning propofol misuse in medical professionals, specifically relating to the individual demographics of those misusing propofol and the outcomes of propofol misuse.

Methods: We conducted a retrospective scoping review of the literature using a modified PRISMA approach. We used MEDLINE, EMBASE, and PsycINFO databases to identify relevant studies based on search terms. Studies describing individual medical professionals misusing propofol were included.

Results: Twenty-four articles describing 88 individual cases of propofol misuse were included for data charting and analysis. Anesthesiologists and certified registered nurse anesthetists were most commonly identified. Death was a common method of identification of misuse, while rehabilitation and death were common final outcomes associated with propofol misuse.

Conclusions: Despite knowledge of the pharmacokinetic and pharmacodynamic properties of propofol by those misusing this medication, death was a common outcome reported in the literature. Data related to long-term outcomes including re-entry to clinical practice or success of rehabilitation were limited.

Abstract
Propfol-remifentanil-based total intravenous anaesthesia has dominated recent clinical practice due to its favourable pharmacokinetic profile. Interruption in remifentanil supply has presented an opportunity to diversify or even avoid the use of opioids and consider adjuncts to propofol-based total intravenous anaesthesia. Propofol, while a potent hypnotic, is not an effective analgesic. The administration of opioids, along with other adjuncts such as α-2 adrenoceptor agonists, magnesium, lidocaine, ketamine and nitrous oxide provide surgical anaesthesia and avoids large doses of propofol being required. We provide an overview of both target-control and manual infusion regimes for the alternative opioids: alfentanil, sufentanil and fentanyl. The optimal combination of hypnotic-opioid dose, titration sequence and anticipated additional postoperative analgesia required depend on the chosen combination. In addition, we include a brief discussion on the role of non-opioid adjuncts in total intravenous anaesthesia, suggested doses and expected reduction in propofol dose.

Tanya Rochelle Farrell and Britta S. von Ungern- Sternberg are both ANZCA fellows.

Abstract
Laryngotracheal injury is an increasingly common complication of intubation and mechanical ventilation, with an estimated 87% of intubated and ventilated patients developing a laryngotracheal injury often preventing their rehabilitation from acute illness. Laryngotracheal injuries encompass a diverse set of pathologies including inflammation and oedema in addition to vocal cord ulceration and paralysis, granuloma, stenosis, and scarring. The existing literature has identified several factors including intubation duration, endotracheal tube size, type and cuff pressures, and technical factors including the skill and experience of the endoscopist. Despite these associations, a key aspect in the sequelae of laryngotracheal injuries is due to reflux and is not clearly related to iatrogenic and mechanical factors.Laryngopharyngeal reflux is a type of reflux that contaminates the upper aerodigestive tract. The combination of patient positioning and continuous nasogastric tube feeding act to affect the upper aerodigestive tract with acidic and non-acidic refluxate that causes direct and indirect mucosal injury impeding healing.Despite laryngopharyngeal reflux being an established and recognised causative factor of upper aerodigestive tract inflammatory pathology and laryngotracheal injury, it is very understudied in critical care. Further, there is yet to be an agreed pathway to assess, manage and prevent laryngotracheal injury in intubated and ventilated patients. The incidence of laryngopharyngeal reflux in the intubated and mechanically ventilated patient in the intensive care unit is currently unknown. Prospective studies may allow us to understand further potential mechanisms of upper aerodigestive tract injury due to laryngopharyngeal reflux and herald the development of preventative and management strategies of laryngopharyngeal reflux-mediated upper aerodigestive tract injury in critically ill patients.

Abstract
Sedated patients have graded levels of consciousness and perceptual connection with the outside world. Disconnection is associated with widespread changes in the electroencephalogram, whereas full unconsciousness is linked with decreased activity specifically in the deep midline regions of the brain. These findings can be interpreted within the predictive coding model of consciousness as differences in model generation vs discrepancy detection. Anaesthetists should be cognisant that apparently unresponsive patients might still have some ongoing partially disconnected consciousness activity.

Abstract
Anaesthetic choice for large joint surgery can impact postoperative outcomes, including mortality. The extent to which the impact of anaesthetic choice on postoperative mortality varies within patient populations and the extent to which anaesthetic choice is changing over time remain under-explored both internationally and in the diverse New Zealand context. In a national study of 199,211 hip and knee replacement procedures conducted between 2005 and 2017, we compared postoperative mortality among those receiving general, regional or general plus regional anaesthesia. Focusing on unilateral (n=86,467) and partial (n=13,889) hip replacements, we assessed whether some groups within the population are more likely to receive general, regional or general plus regional anaesthesia than others, and whether mortality risk varies depending on anaesthetic choice. We also examined temporal changes in anaesthetic choice over time. Those receiving regional alone or general plus regional for unilateral hip replacement appeared at increased risk of 30-day mortality compared to general anaesthesia alone, even after adjusting for differences in terms of age, ethnicity, deprivation, rurality, comorbidity, American Society of Anesthesiologists physical status score and admission type (e.g. general plus regional: adjusted hazard ratio (adj. HR)=1.94, 95% confidence intervals (CI) 1.32 to 2.84). By contrast, we observed lower 30-day mortality among those receiving regional anaesthesia alone compared to general alone for partial hip replacement (adj. HR=0.86, 95% CI 0.75 to 0.97). The latter observation contrasts with declining temporal trends in the use of regional anaesthesia alone for partial hip replacement procedures. However, we recognise that postoperative mortality is one perioperative factor that drives anaesthetic choice.

Abstract
The Australian and New Zealand College of Anaesthetists (ANZCA) recently reviewed and updated the guideline on equipment to manage a difficult airway. An ANZCA-established document development group, which included representatives from the Australasian College for Emergency Medicine and the College of Intensive Care Medicine of Australia and New Zealand, performed the review, which is based on expert consensus, an extensive literature review, and bi-nationwide consultation. The guideline (PG56(A) 2021, https://www.anzca.edu.au/getattachment/02fe1a4c-14f0-4ad1-8337-c281d26bfa17/PS56-Guideline-on-equipment-to-manage-difficult-airways) is accompanied by a detailed background paper (PG56(A)BP 2021, https://www.anzca.edu.au/getattachment/9ef4cd97-2f02-47fe-a63a-9f74fa7c68ac/PG56(A)BP-Guideline-on-equipment-to-manage-difficult-airways-Background-Paper), from which the current recommendations are reproduced on behalf of, and with the permission of, ANZCA. The updated 2021 guideline replaces the 2012 version and aims to provide an updated, objective, informed, transparent, and evidence-based review of equipment to manage difficult airways.

No abstract available.

Methods: In this pragmatic, international, noninferiority trial, we randomly assigned 8880 adult patients who were undergoing nonurgent, noncardiac surgery of at least 2 hours' duration, with a skin incision length longer than 5 cm and a postoperative overnight hospital stay, to receive 8 mg of intravenous dexamethasone or matching placebo while under anesthesia. Randomization was stratified according to diabetes status and trial center. The primary outcome was surgical-site infection within 30 days after surgery. The prespecified noninferiority margin was 2.0 percentage points.

Results: A total of 8725 participants were included in the modified intention-to-treat population (4372 in the dexamethasone group and 4353 in the placebo group), of whom 13.2% (576 in the dexamethasone group and 572 in the placebo group) had diabetes mellitus. Of the 8678 patients included in the primary analysis, surgical-site infection occurred in 8.1% (354 of 4350 patients) assigned to dexamethasone and in 9.1% (394 of 4328) assigned to placebo (risk difference adjusted for diabetes status, -0.9 percentage points; 95.6% confidence interval [CI], -2.1 to 0.3; P<0.001 for noninferiority). The results for superficial, deep, and organ-space surgical-site infections and in patients with diabetes were similar to those of the primary analysis. Postoperative nausea and vomiting in the first 24 hours after surgery occurred in 42.2% of patients in the dexamethasone group and in 53.9% in the placebo group (risk ratio, 0.78; 95% CI, 0.75 to 0.82). Hyperglycemic events in patients without diabetes occurred in 22 of 3787 (0.6%) in the dexamethasone group and in 6 of 3776 (0.2%) in the placebo group.

Conclusions: Dexamethasone was noninferior to placebo with respect to the incidence of surgical-site infection within 30 days after nonurgent, noncardiac surgery. (Funded by the Australian National Health and Medical Research Council and others; PADDI Australian New Zealand Clinical Trials Registry number, ACTRN12614001226695.).

Methods/analysis: This is a pragmatic, multicentre, randomised, controlled, non-inferiority trial. A total of 8880 patients undergoing elective major surgery will be enrolled. Participants will be randomly allocated to receive either dexamethasone 8 mg or placebo intravenously following the induction of anaesthesia in a 1:1 ratio, stratified by centre and diabetes status. Patient enrolment into the trial is ongoing. The primary outcome is surgical site infection at 30 days following surgery, defined according to the Centre for Disease Control criteria.

Ethics/dissemination: The PADDI trial has been approved by the ethics committees of over 45 participating sites in Australia, New Zealand, Hong Kong, South Africa and the Netherlands. The trial has been endorsed by the Australia and New Zealand College of Anaesthetists Clinical Trials Network and the Australian Society for Infectious Diseases Clinical Research Network. Participant recruitment began in March 2016 and is expected to be complete in mid-2019. Publication of the results of the PADDI trial is anticipated to occur in early 2020.

Trial registration number: ACTRN12614001226695.

Keywords: Dexamethasone; Diabetes; Postoperative Nausea and Vomiting; Surgical Wound Infection; glucocorticoid.

Abstract
Objective: To quantify the risk of adverse postoperative outcomes in pediatric patients with COVID-19 infection.

Methods: We searched PubMed, Embase, Cochrane Library from December 2019 to 21 April 2023. Observational cohort studies that reported postoperative early mortality and pulmonary complications of pediatric patients with confirmed COVID-19-positive compared with COVID-19-negative were eligible for inclusion. We excluded pediatric patients underwent organ transplantation or cardiac surgery. Reviews, case reports, letters, and editorials were also excluded. We used the Newcastle-Ottawa Scale to assess the methodological quality and risk of bias for each included study. The primary outcome was postoperative early mortality, defined as mortality within 30 days after surgery or during hospitalization. The random-effects model was performed to assess the pooled estimates, which were expressed as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI).

Results: 9 studies involving 23,031 pediatric patients were included, and all studies were rated as high quality. Compared with pediatric patients without COVID-19, pediatric patients with COVID-19 showed a significantly increased risk of postoperative pulmonary complications (PPCs) (RR = 4.24; 95% CI 2.08-8.64). No clear evidence was found for differences in postoperative early mortality (RR = 0.84; 95% CI 0.34-2.06), postoperative intensive care unit (ICU) admission (RR = 0.80; 95% CI 0.39-1.68), and length of hospital stay (MD = 0.35, 95% CI -1.81-2.51) between pediatric patients with and without COVID-19.

Conclusion: Perioperative COVID-19 infection was strongly associated with increased risk of PPCs, but it did not increase the risk of postoperative early mortality, the rate of postoperative ICU admission, and the length of hospital stay in pediatric patients. Our preplanned sensitivity analyses confirmed the robustness of our study findings.

Keywords: COVID-19; Mortality; Pediatric; Postoperative outcome.

Abstract
Introduction: Although manifestation of SARS-CoV-2 infection in children is gene-rally mild or asymptomatic, anaesthetic implications of the infection in children are still a matter of concern. Single reports suggest that patients with SARS-CoV-2 infection are at higher risk of anaesthetic complications.

Material and methods: We performed a retrospective, case control study analysing the risk of general anaesthesia in SARS-CoV-2 infected children admitted to a tertiary paediatric university hospital for the purpose of urgent procedures requiring anaesthesia between April 1st and September 30 th , 2021. The control group consisted of SARS-CoV-2 negative children consecutively anaesthetised for the same reasons during the first month of observation. Our hypothesis was: general anaesthesia can be safely performed in SARS-CoV-2 infected children. Study endpoints: primary - anaesthetic respiratory complications (bronchospasm, laryngospasm, intraoperative desaturation below 94%, desaturation below 94% after awakening, unplanned postoperative mechanical ventilation); secondary - hospital length of stay, thrombotic, cardiac, haemorrhagic events, ICU admission, deaths during hospitalisation.

Results: The examined group consisted of 58 SARS-CoV-2 infected children, the matched control group of 198 patients. The rate of complications in both groups was very low, with no significant difference between the groups. The only differences observed were a higher frequency of desaturations in the awakening period and longer time of hospitalisation in SARS-CoV-2 infected patients. Multivariate logistic regression analysis showed that physical status of the patient and duration of the procedure were the main factors influencing the risk of complications.

Conclusions: In our experience anaesthesia of SARS-CoV-2 infected children can be safely performed.

Abstract
Background: Despite the fervent scientific effort, a state-of-the art assessment of the different causes of hypoxemia (shunt, ventilation-perfusion mismatch and diffusion limitation) in COVID-19 ARDS is currently lacking. In this study we aimed to understand what is the relative contribution of the different mechanisms of hypoxemia in this disease and what is their relationship with the distribution of tissue and blood within the lung.

Methods: We prospectively enrolled 10 patients with COVID-19 ARDS, intubated for <7 days. We performed the Multiple Inert Gas Elimination Technique (MIGET) and a Dual-Energy Computed Tomography (DECT), which was quantitatively analyzed both for the tissue and blood volume. We also recorded variables related to the respiratory mechanics and invasive hemodynamics (PiCCO).

Results: The population (51±15 years, PaO2/FiO2 172±86 mmHg) had a mortality of 50%. MIGET showed a shunt of 25±16% and a deadspace of 53±11%. The ventilation and perfusion were mismatched (LogSD, Q 0.86±0.33). Unexpectedly, we also found evidence of diffusion limitation/post-pulmonary shunting (Predicted PaO2= 1.6*measured PaO2 - 37.5 mmHg). In the well-aerated regions, the blood volume was in excess compared to the tissue, while the opposite happened in the atelectasis. Shunt was proportional to the blood volume of the atelectasis (R 2=0.70, p=0.003). VA/QT mismatch was correlated with the blood volume of the poorly-aerated tissue (R 2=0.54, p=0.016). The overperfusion coefficient was related to PaO2/FiO2 (R 2=0.66, p=0.002), excess tissue mass (R 2=0.84, p<0.001) and to EtCO2/PaCO2 (R 2=0.63, p=0.004).

Conclusions: These data support the hypothesis of a highly multifactorial genesis of hypoxemia. Evidence from autoptic studies (i.e., opening of Intrapulmonary Bronchopulmonary Anastomosis) may explain the unexpected post-pulmonary shunting. The hyperperfusion might be related to the disease severity.

Abstract
This survey investigated the prevalence of de novo widespread musculoskeletal post-COVID pain and risk factors for its development in non-hospitalized COVID-19 survivors. A nationwide exploratory cross-sectional study was conducted including a cohort of 593,741 Danish residents that had suffered from a SARS-CoV-2 infection from March 2020 to December 2021. A questionnaire was distributed to the Danish population via digital mail system (e-Boks). Self-reported demographic data, previous medical comorbidities (diagnosed), socioeconomic data, time of infection, prior chronic pain conditions (diagnosed), development of de novo widespread pain after infection, pain medication, and pain intensity information were collected. Responders consisted of 130,443 non-hospitalized participants (58.2% women; mean age: 50.2 years). At a mean of 14.4 (SD 6.0) months after infection, 6,875 (5.3%) patients reported the presence of de novo widespread musculoskeletal post-COVID pain. Almost 75% of the patients reported a moderate to severe intensity of the pain. In conclusion, de novo widespread post-COVID pain was present in 5.3% of non-hospitalized COVID-19 survivors one year after infection (14.4±6.0 months). Older age, female sex, higher body mass index, and history of migraine, whiplash, stress, type-2 diabetes, neurological disorders, and lower socioeconomic status, were risk factors associated with the development of de novo widespread post-COVID pain in non-hospitalized patients. As de novo widespread pain is considered a sign of sensitization, this group will require specialized pain management attention. PERSPECTIVE: This article presents de novo widespread post-COVID pain prevalence in a cohort of 130,443 citizens infected with COVID-19. The study identifies potential risk factors associated with development of these new pain symptoms. The results may increase focus on this patient group and potentially help identifying predictors for post-infection pain development.

Keywords: COVID-19; de novo widespread pain; non-hospitalization; post-COVID; risk factors.

Abstract
Importance: To ensure that youths can make informed decisions about their health, it is important that health recommendations be presented for understanding by youths.

Objective: To compare understanding, accessibility, usability, satisfaction, intention to implement, and preference of youths provided with a digital plain language recommendation (PLR) format vs the original standard language version (SLV) of a health recommendation.

Design, setting, and participants: This pragmatic, allocation-concealed, blinded, superiority randomized clinical trial included individuals from any country who were 15 to 24 years of age, had internet access, and could read and understand English. The trial was conducted from May 27 to July 6, 2022, and included a qualitative component.

Interventions: An online platform was used to randomize youths in a 1:1 ratio to an optimized digital PLR or SLV format of 1 of 2 health recommendations related to the COVID-19 vaccine; youth-friendly PLRs were developed in collaboration with youth partners and advisors.

Main outcomes and measures: The primary outcome was understanding, measured as the proportion of correct responses to 7 comprehension questions. Secondary outcomes were accessibility, usability, satisfaction, preference, and intended behavior. After completion of the survey, participants indicated their interest in completing a 1-on-1 semistructured interview to reflect on their preferred digital format (PLR or SLV) and their outcome assessment survey response.

Results: Of the 268 participants included in the final analysis, 137 were in the PLR group (48.4% female) and 131 were in the SLV group (53.4% female). Most participants (233 [86.9%]) were from North and South America. No significant difference was found in understanding scores between the PLR and SLV groups (mean difference, 5.2%; 95% CI, -1.2% to 11.6%; P = .11). Participants found the PLR to be more accessible and usable (mean difference, 0.34; 95% CI, 0.05-0.63) and satisfying (mean difference, 0.39; 95% CI, 0.06-0.73) and had a stronger preference toward the PLR (mean difference, 4.8; 95% CI, 4.5-5.1 [4.0 indicated a neutral response]) compared with the SLV. No significant difference was found in intended behavior (mean difference, 0.22 (95% CI, -0.20 to 0.74). Interviewees (n = 14) agreed that the PLR was easier to understand and generated constructive feedback to further improve the digital PLR.

Conclusions and relevance: In this randomized clinical trial, compared with the SLV, the PLR did not produce statistically significant findings in terms of understanding scores. Youths ranked it higher in terms of accessibility, usability, and satisfaction, suggesting that the PLR may be preferred for communicating health recommendations to youths. The interviews provided suggestions for further improving PLR formats.

Abstract
Objective: In response to COVID-19, virtual, group-based interdisciplinary pain management programmes (PMPs) were rapidly implemented. This included implementing different intensities and formats of virtual PMPs to address a range of patient needs and complexity. This observational study investigated outcomes associated with virtual high and low intensity and pre-neuromodulation PMPs based on Acceptance and Commitment Therapy (ACT) as part of routine care during the pandemic.

Methods: Depending on patients' needs, participants completed a virtual high- or low-intensity PMP, or a virtual PMP in preparation for neuromodulation, from June 2020 to June 2022. Participants completed standardized measures of pain intensity and interference, work and social adjustment, depression, and pain acceptance before and after treatment. Data from 2018 and 2019 for in-person residential (n=561), outpatient (n=123), and pre-neuromodulation (n=207) PMPs were also examined to provide an historical benchmark of performance.

Abstract
Purpose: Older adults with COVID-19 have a high prevalence of complications and mortality during hospitalization. Given the large proportion of older adults requiring admission to an intensive care unit (ICU), we aimed to describe the management and outcomes of older adults with COVID-19 requiring ICU care and identify predictors of hospital mortality.

Methods: We included consecutive patients ≥ 65 yr of age who were admitted between 11 March 2020 and 30 June 2021 to one of five Toronto (ON, Canada) ICUs with a primary diagnosis of SARS-CoV-2 infection in a retrospective cohort study. Patient characteristics, ICU treatment, and outcomes were recorded. We used multivariable logistic regression to identify predictors of in-hospital mortality.

Abstract
Objective: To review if tests for suspected COVID-19 were performed according to the Ministry of Health (MoH) case definitions, identify patterns associated with testing outside of the case definition, and discuss the potential impacts on hospital services.

Methods: This was a retrospective audit of patients presenting to the Wellington Hospital ED between 24 March 2020 and 27 April 2020 who were swabbed for COVID-19 in ED. Swabs were audited against the March 15th and April 8th MoH COVID-19 case definitions.

Results: Five hundred and thirty-six COVID-19 swabs for 518 patients were taken during the study period. There was poor alignment of testing with the March 15th case definition, with only 11.6% of the 164 swabs taken during this period meeting the case definition. Of the 145 swabs that did not meet the case definition, the majority (n = 119, 82.1%) met symptom criteria only. Alignment of testing with the wider April 8th case definition was much higher with 88.2% meeting criteria. Factors associated with being swabbed despite not meeting the case definitions included fever >38°, a diagnosis of cancer, subsequent hospital admission, and for the March case definition only 'contact with a traveller'.

Conclusion: There were associations found between testing outside of criteria and specific variables potentially perceived as high-risk. Poor alignment of testing with case definitions can impact hospital services through the (mis)use of limited laboratory testing capacity and implications for resource management. Improved communication and feedback between clinicians and policymakers may improve case definition implementation in a clinical setting.

Keywords: COVID-19; Women physicians; burnout; gender equity.

Abstract
Background: COVID-19 forced healthcare systems to make unprecedented changes in clinical care processes. We hypothesized that the COVID-19 pandemic adversely impacted timely access to care, perioperative processes, and clinical outcomes for pediatric patients undergoing primary appendectomy.

Methods: We conducted a retrospective, international, multicenter study using matched cohorts within participating centers of the international PEdiatric Anesthesia COVID-19 Collaborative (PEACOC). Patients < 18 years old were matched using age, ASA-PS status, and sex. The primary outcome was the difference in hospital length of stay of patients undergoing primary appendectomy during a 2-month period early in the COVID-19 pandemic (April-May 2020) compared to pre-pandemic (April-May 2019). Secondary outcomes included time to appendectomy and the incidence of complicated appendicitis.

Results: 3351 cases from 28 institutions were available with 1684 cases in the pre-pandemic cohort matched to 1618 in the pandemic cohort. Hospital length of stay was statistically significantly different between the two groups: 29 hours (IQR: 18, 67) in the pandemic cohort versus 28 hours (IQR: 18, 79) in the pre-pandemic cohort (adjusted coefficient, 1; 95% CI 0.39 to 1.61, P<0.001), but this difference was small. Eight centers demonstrated a statistically significantly longer hospital length of stay in the pandemic period compared to the pre-pandemic period, while 13 were shorter and 7 did not observe a statistically significant difference. During the pandemic period, there was a greater occurrence of complicated appendicitis, pre-pandemic 313 (18.6%) versus pandemic 389 (24.1%), absolute difference of 5.5% (adjusted OR, 1.32; [95% CI 1.1 to 1.59]; P=0.003). Preoperative SARS CoV-2 testing was associated with significantly longer time-to-appendectomy, 720 minutes (IQR: 430, 1112) with testing versus 414 minutes (IQR: 231, 770) without testing, adjusted coefficient, 306 minutes, (95% CI 241 to 371, P <0.001), and longer hospital length of stay, 31 hours (IQR: 20, 83) with testing versus 24 hours (IQR: 14, 68) without testing, adjusted coefficient, 7.0, (95% CI 2.7 to 11.3, P=0.002).

Discussion: For children undergoing appendectomy, the COVID-19 pandemic did not significantly impact hospital length of stay.

Abstract
Background: The COVID-19 pandemic has greatly affected access to elective surgery, largely because of concerns for patients and healthcare workers. A return to normal surgery workflow depends on the prevalence and transmission of coronavirus in elective surgical patients. The aim of this study was to determine the prevalence of active SARS-coronavirus-2 infection during a second wave among patients admitted to hospital for elective surgery in Victoria.

Methods: Prospective cohort study across eight hospitals in Victoria during July-August 2020 was conducted enrolling adults and children admitted to hospital for elective surgery or interventional procedure requiring general anaesthesia. Study outcomes included a positive polymerase chain reaction (PCR) test for SARS-CoV-2 in the preoperative period (primary outcome), and for those with a negative test preoperatively, the incidence of a positive PCR test for SARS-CoV-2 in the post-operative period.

Results: We enrolled 4965 elective adult and paediatric surgical patients from 15 July to 31 August 2020. Four patients screened negative on questionnaire but had a positive PCR test for coronavirus, resulting in a Bayesian estimated prevalence of 0.12% (95% probability interval 0-0.26%). There were no reports of healthcare worker infections linked to elective surgery during and up to 2 weeks after the study period.

Conclusion: The prevalence of SARS-CoV-2 in asymptomatic elective surgical patients during a second wave was approximately 1 in 833. Given the very low likelihood of coronavirus transmission, and with existing current hospital capacity, recommencement of elective surgery should be considered. A coronavirus screening checklist should be mandated for surgical patients.

Abstract
Background: The study aimed to estimate the prevalence of active or previous SARS-CoV-2 infection in asymptomatic adults admitted for elective surgery in Australian hospitals. This surveillance activity was established as part of the National Pandemic Health Intelligence Plan.

Methods: Participants (n = 3037) were recruited from 11 public and private hospitals in four states (NSW, Vic, SA and WA) between 2 June and 17 July 2020, with an overall 66% participation rate. Presence of SARS-CoV-2 viral RNA was assessed by Reverse Transcriptase - Polymerase Chain Reaction (RT-PCR) analysis of nasopharyngeal swabs taken after induction of anaesthesia. Presence of anti-SARS-CoV-2 antibodies was assessed by analysis of serum collected at the same time using a novel dual-antigen ELISA assay.

Results: No patient (0/3010) returned a positive RT-PCR result. The Bayesian estimated prevalence of active infection of 0.02% (95% probability interval 0.00-0.11%), with the upper endpoint being 1 in 918. Positive serology (IgG) was observed in 15 of 2991 patients, with a strong positive in five of those individuals (Bayesian estimated seroprevalence 0.16%; 95% probability interval 0.00-0.47%).

Conclusion: These results confirm that during periods of low community prevalence of SARS-CoV-2 elective surgery patients without fever or respiratory symptoms had a very low prevalence of active SARS-CoV-2 infection.

Abstract
The risk of COVID-19 in those with chronic pain is unknown. We investigated whether self-reported chronic pain was associated with COVID-19 hospitalisation or mortality. UK Biobank recruited 502,624 participants aged 37 to 73 years between 2006 and 2010. Baseline exposure data, including chronic pain (>3 months, in at least 1 of 7 prespecified body sites) and chronic widespread pain (>3 months, all over body), were linked to COVID-19 hospitalisations or mortality. Univariable or multivariable Poisson regression analyses were performed on the association between chronic pain and COVID-19 hospitalisation and Cox regression analyses of the associations with COVID-19 mortality. Multivariable analyses adjusted incrementally for sociodemographic confounders, then lifestyle risk factors, and finally long-term condition count. Of 441,403 UK Biobank participants with complete data, 3180 (0.7%) were hospitalised for COVID-19 and 1040 (0.2%) died from COVID-19. Chronic pain was associated with hospital admission for COVID-19 even after adjustment for all covariates (incidence rate ratio 1.16; 95% confidence interval [CI] 1.08-1.24; P < 0.001), as was chronic widespread pain (incidence rate ratio 1.33; 95% CI 1.06-1.66; P = 0.012). There was clear evidence of a dose-response relationship with number of pain sites (fully adjusted global P -value < 0.001). After adjustment for all covariates, there was no association between chronic pain (HR 1.01; 95% CI 0.89-1.15; P = 0.834) but attenuated association with chronic widespread pain (HR 1.50, 95% CI 1.04-2.16, P -value = 0.032) and COVID-19 mortality. Chronic pain is associated with higher risk of hospitalisation for COVID-19, but the association with mortality is unclear. Future research is required to investigate these findings further and determine whether pain is associated with long COVID.

Abstract
Introduction: The global COVID-19 pandemic highlighted the importance of protecting frontline healthcare workers from novel respiratory infections while also exposing the limited instruction that medical students receive on proper donning of personal protective equipment (PPE) and more importantly the safe doffing of contaminated PPE to minimize their risk of nosocomial infection. The best methods of providing this kind of instruction have not yet been determined.

Methods: Anesthesiology interns and CA-1 residents were trained on proper PPE donning and doffing for AGPs using a methodology based on Miller's pyramid and following a "knows-knows how-shows-does" progression. Participants donned PPE without instruction and were sprayed with Glo Germ® to identify areas of contamination, after which they received both video and in-person instruction on best practices for donning and doffing PPE for AGPs. Following instruction, they again donned PPE and were sprayed with Glo Germ® to identify areas of contamination.

Results: 54 participants completed the study. Before training, overall donning compliance was 60% and overall doffing compliance was 48%. Overall, 70% were contaminated after PPE doffing, with 46% having multiple sites of contamination. After training, donning compliance increased by nearly 30% (P < 0.001), doffing compliance increased by over 20% (P < 0.001), and overall contamination decreased by nearly 30% (P = 0.029), with multiple-site contamination decreasing to only 6% (P = 0.013).

Discussion: While best methods for providing instruction regarding topics such as PPE donning and doffing have not yet been determined, we have demonstrated that the underlying knowledge base from medical school regarding proper donning and doffing for respiratory isolation is insufficient for preventing self-contamination, and that Miller's pyramid-based training using both video and in-person instruction combined with task execution by learners can improve compliance with PPE donning and doffing protocols and more importantly decrease skin contamination among a group of early training anesthesiology residents.

Abstract
Purpose: The aim of this study was to determine the changes in the physical, mental, and social conditions of operating room nurses and their personal experiences during the COVID-19 pandemic.

Design: The study applied a qualitative research design that included the content analysis method.

Methods: Face-to-face interviews were conducted online with 26 operating room nurses. Analysis of the data was completed in six steps using the content analysis method.

Findings: Four main themes emerged from the interviews: physical effect of the COVID-19 pandemic on operating room nurses, psychological effect of the COVID-19 pandemic on operating room nurses, operating room nurses' perceptions on the training given to them during the COVID-19 pandemic, and effects of the COVID-19 pandemic on health care worker and patient safety and nursing care.

Conclusions: This study contributes new findings on the experiences of operating nurses during the COVID-19 pandemic to the relevant literature. The results of the study indicated that the nurses were negatively affected both physically and psychologically during this period, and that this directly affected patient care.

Abstract
Background: Intensive care unit (ICU) patients with Coronavirus disease 2019 (COVID-19) have an increased risk of thromboembolic complications. We describe the occurrence of thromboembolic and bleeding events in all ICU patients with COVID-19 in Denmark during the first and second waves of the pandemic.

Methods: This was a sub-study of the Danish Intensive Care Covid database, in which all patients with SARS-CoV-2 admitted to Danish ICUs from 10th March 2020 to 30th June 2021 were included. We registered coagulation variables at admission, and all thromboembolic and bleeding events, and the use of heparins during ICU stay. Variables associated with thrombosis and bleeding and any association with 90-day mortality were estimated using Cox regression analyses.

Results: We included 1369 patients in this sub-study; 158 (12%, 95% confidence interval 10-13) had a thromboembolic event in ICU and 309 (23%, 20-25) had a bleeding event, among whom 81 patients (6%, 4.8-7.3) had major bleeding. We found that mechanical ventilation and increased D-dimer were associated with thrombosis and mechanical ventilation, low platelet count and presence of haematological malignancy were associated with bleeding. Most patients (76%) received increased doses of thromboprophylaxis during their ICU stay. Thromboembolic events were not associated with mortality in adjusted analysis (hazard ratio 1.35 [0.91-2.01, p = .14], whereas bleeding events were 1.55 [1.18-2.05, p = .002]).

Conclusions: Both thromboembolic and bleeding events frequently occurred in ICU patients with COVID-19. Based on these data, it is not apparent that increased doses of thromboprophylaxis were beneficial.

Abstract
Background: Under the hypothesis that mechanical power ratio could identify the spontaneously breathing patients with higher risk of respiratory failure, we assessed lung mechanics in non-intubated patients with COVID-19 pneumonia aimed at: 1) describe their characteristics; 2) compare lung mechanics between patients who received respiratory treatment escalation and those who did not; 3) identify variables associated with the need for respiratory treatment escalation.

Methods: Secondary analysis of prospectively enrolled cohort involving 111 consecutive spontaneously breathing adults receiving continuous positive airway pressure, enrolled from September 2020 to December 2021. Lung mechanics, other previously reported predictive indices were calculated, as well as a novel variable: the mechanical power ratio (the ratio between the actual and the expected baseline mechanical power). Patients were grouped according to the outcome: 1) no-treatment escalation (patient supported in continuous positive airway pressure until improvement); 2) treatment escalation (escalation of the respiratory support to non-invasive or invasive mechanical ventilation); and the association between lung mechanics/predictive scores and outcome was assessed.

Results: At day 1, patients undergoing treatment escalation had similar spontaneous tidal volume than patients who did not (7.1 ± 1.9 vs 7.1 ± 1.4 mL/KgIBW; p=0.990). In contrast, they showed higher respiratory rate (20 ± 5 vs 18 ± 5 bpm; p=0.028), minute ventilation (9.2 ± 3.0 vs 7.9 ± 2.4 L/min; p=0.011), tidal pleural pressure (8.1 ± 3.7 vs 6.0 ± 3.1 cmH2O; p=0.003), mechanical power ratio (2.4 ± 1.4 vs 1.7 ± 1.5; p=0.042) and lower PaO2/FiO2 (174 ± 64 vs 220 ± 95; p=0.007). Mechanical power (AUC 0.738 [95%CI 0.636-0.839] p<0.001), the mechanical power ratio (AUC 0.734 [95%CI 0.625-0.844] p <0.001) and the pressure-rate index (AUC 0.733 [95%CI 0.631-0.835] p <0.001) showed the highest AUC.

Conclusions: In this COVID-19 cohort, tidal volume was similar in patients undergoing treatment escalation and in patients who did not; mechanical power, its ratio, and pressure-rate index were the variables presenting the highest association with the clinical outcome.

Abstract
Introduction: COVID-19 is associated with severe respiratory distress and high mortality. We investigated the evolution of the respiratory mechanics in COVID-19 acute respiratory distress syndrome (ARDS) and the occurrence of a restrictive respiratory pattern.

Material and methods: A retrospective, single-centre study including patients admitted to the ICU during the first wave of the pandemic (March-April 2020).

Results: A total of 141 consecutive patients were included. Many patients developed a restrictive pattern of respiratory mechanics during the course of the disease. Fifty-two patients died in the hospital (36.8%). In 29 cases (58% of the deceased) death was associated with a pattern of pulmonary mechanics, indicating a restrictive evolution of ARDS. Other diagnoses related to death were pulmonary embolism (n = 7, 14%), septic shock (n = 17, 33%), and other causes (n = 10, 20%), with some patients combining at least 2 of these diagnoses. In a multivariate analysis, age (OR = 1.06; 95% CI: 1.01-1.12; P = 0.029) and the administration of steroid pulses (OR = 2.7; 95% CI: 1.1-6.8; P = 0.03) were associated with the development of a restrictive pulmonary pattern and a higher level of plasmatic interleukin-6.

Conclusions: COVID-19 ARDS is associated with high mortality associated with a specific pattern of respiratory mechanics and sustained activation of innate immunological response. Age and administration of high-dose steroid pulses are associated with this clinical picture.

Abstract
Objectives: To determine in patients with acute respiratory distress syndrome (ARDS) on venovenous extracorporeal membrane oxygenation (VV ECMO) whether reducing driving pressure (ΔP) would decrease plasma biomarkers of inflammation and lung injury (interleukin-6 [IL-6], IL-8, and the soluble receptor for advanced glycation end-products sRAGE).

Design: A single-center prospective physiologic study.

Setting: At a single university medical center.

Participants: Adult patients with severe COVID-19 ARDS on VV ECMO.

Interventions: Participants on VV ECMO had the following biomarkers measured: (1) pre-ECMO with low-tidal-volume ventilation (LTVV), (2) post-ECMO with LTVV, (3) during low-driving-pressure ventilation (LDPV), (4) after 2 hours of very low driving-pressure ventilation (V-LDPV, main intervention ΔP = 1 cmH2O), and (5) 2 hours after returning to LDPV.

Main measurements and results: Twenty-six participants were enrolled; 21 underwent V-LDPV. There was no significant change in IL-6, IL-8, and sRAGE from LDPV to V-LDPV and from V-LDPV to LDPV. Only participants (9 of 21) with nonspontaneous breaths had significant change (p < 0.001) in their tidal volumes (Vt) (mean ± SD), 1.9 ± 0.5, 0.1 ± 0.2, and 2.0 ± 0.7 mL/kg predicted body weight (PBW). Participants with spontaneous breathing, Vt were unchanged-4.5 ± 3.1, 4.7 ± 3.1, and 5.6 ± 2.9 mL/kg PBW (p = 0.481 and p = 0.065, respectively). There was no relationship found when accounting for Vt changes and biomarkers.

Conclusions: Biomarkers did not significantly change with decreased ΔPs or Vt changes during the first 24 hours post-ECMO. Despite deep sedation, reductions in Vt during V-LDPV were not reliably achieved due to spontaneous breaths. Thus, patients on VV ECMO for ARDS may have higher Vt (ie, transpulmonary pressure) than desired despite low ΔPs or Vt.

Abstract
Background: Chronic pain symptoms are distressing conditions that necessitate regular visits to pain therapists and may require interventions, however, the COVID-19 pandemic has caused patients and their therapists to limit both visits and interventions with the transition to telehealth, with little or no preparation or training. This has resulted in the extensive use of over-the counter analgesia and corticosteroids.

Objectives: Our study aimed to evaluate the effect of the COVID-19 pandemic on the rates of counseling and interventional pain management therapies (IPMT), and determine the effects of implementing an infection control program (ICP) and mandating personal protective equipment (PPE) on these rates.

Study design: Prospective multicenter survey, based on an online self-assessed questionnaire.

Setting: Departments of Anesthesia, Pain, Intensive Care Unit, Physical Medicine, Rheumatology, and Rehabilitation at Egyptian University hospitals.

Methods: A self-assessed questionnaire was uploaded on Google forms and links were sent to enrolled therapists with an identification number to allow self-administration and privacy. Feedback was analyzed by 2 authors who were blinded to the identity of the responders.

Results: A total of 57.9% of responders increased their patients' contact by phone and video conference. Within 1-4 months after the outbreak began, 59% stopped in-person contact and 38.2% stopped their IPM practice. Prescriptions of analgesics and oral steroids increased by about 50%. The majority of responders complained of a shortage of ventilation appliances in their workplaces. About 50% of them always use ICP, 85% use surgical masks, 61% use gloves, and 45% wear gowns when meeting with patients. After the application of PPE, 45.5% of responders increased their consultation rate and 40% increased their rate of IPMT.

Limitations: This study is limited to being a national study, and so lacked comparative data.

Conclusion: The COVID-19 outbreak seriously affected the rates of in-person consultations and IPMT for patients with chronic pain and increased the rates of consumption of analgesia and oral steroids. Most responders reported a shortage of PPE especially ventilation appliances in workplaces. A high percentage of responders lack interest in ICP and PPE, despite the positive effects of its application on consultation and IPMT rates.