Airway management: Journals & articles

The American Society of Anesthesiologists' (ASA) Task Force on Management of the Difficult Airway has developed a decision tree tool that uses inductive assessments to guide the anesthesiologist's choice of pathway in the ASA's Difficult Airway Algorithm. The tool prompts the anesthesiologist to consider the risk of difficulty with laryngoscopy (direct or indirect) and tracheal intubation, facemask or supraglottic ventilation, gastric contents aspiration, and rapid oxyhemoglobin desaturation. For every airway management event, the approach integrates the anesthesiologist's unique combination of experience, expertise, patient anatomy and disease, equipment availability, and other contextual conditions into the decision process. Entry into the awake intubation pathway is encouraged when the patient is judged at risk of difficult tracheal intubation and one or more of the following: difficult ventilation, significant aspiration risk, and/or rapid oxyhemoglobin desaturation. The decision tree tool is anticipated to improve communication between anesthesiologists and others by clearly identifying those factors of concern and how decision-making is affected by those concerns.

Acute respiratory distress syndrome (ARDS) remains one of the leading causes of morbidity and mortality in critically ill patients despite advancements in the field. Mechanical ventilatory strategies are a vital component of ARDS management to prevent secondary lung injury and improve patient outcomes. Multiple strategies including utilization of low tidal volumes, targeting low plateau pressures to minimize barotrauma, using low FiO2 (fraction of inspired oxygen) to prevent injury related to oxygen free radicals, optimization of positive end expiratory pressure (PEEP) to maintain or improve lung recruitment, and utilization of prone ventilation have been shown to decrease morbidity and mortality. The role of other mechanical ventilatory strategies like non-invasive ventilation, recruitment maneuvers, esophageal pressure monitoring, determination of optimal PEEP, and appropriate patient selection for extracorporeal support is not clear. In this article, we review evidence-based mechanical ventilatory strategies and ventilatory adjuncts for ARDS.

Introduction:
Lean management, a systematic method of reducing waste in manufacturing, is an approach that has led to quality improvement and cost reduction in health systems. Utilization of single-use airway equipment, such as videolaryngoscope (VL) blades and supraglottic airways (SGAs) has helped reduce the risk of cross-contamination and the time and cost associated with reprocessing and sterilization.
Methods:
We examined the efficiency of single-use VL blades and SGAs within our tertiary care health system. Purchasing data were reviewed and compared with device utilization within the electronic medical record to determine the amount of waste of disposable airway equipment. Direct observations (Gemba walks) were made in the operating rooms to assess device utilization. For SGAs, a diagnostic questionnaire was sent to providers regarding approaches to use.
Results:
We found the total cost of opened but unused VL blades equaled $29,267. For SGAs, we found that devices were often opened before use and that there is a 16.67% first-time failure rate for placement of SGAs.
Conclusions:
Through education and organizing device setup, and streamlining communication, there is a possibility to reduce future waste.

Background: Primary graft dysfunction (PGD) is still a major complication in patients undergoing lung transplantation (LTx). Much is unknown about the effect of postoperative mechanical ventilation on outcomes, with debate on the best approach to ventilation.

Aim/purpose: The goal of this study was to generate hypotheses on the association between postoperative mechanical ventilation settings and allograft size matching in PGD development.

Method: This is a retrospective study of LTx patients between September 2011 and September 2018 (n = 116). PGD was assessed according to the International Society of Heart and Lung Transplantation (ISHLT) criteria. Data were collected from medical records, including chest x-ray assessments, blood gas analysis, mechanical ventilator parameters and spirometry.

Results: Positive end-expiratory pressures (PEEP) of 5 cm H2 O were correlated with lower rates of grade 3 PGD. Graft size was important as tidal volumes calculated according to the recipient yielded greater rates of PGD when low volumes were used, a correlation that was lost when donor metrics were used.

Conclusion: Our results highlight a need for greater investigation of the role donor characteristics play in determining post-operative ventilation of a lung transplant recipient. The mechanical ventilation settings on postoperative LTx recipients may have an implication for the development of acute graft dysfunction. Severe PGD was associated with the use of a PEEP higher than 5 and lower tidal volumes and oversized lungs were associated with lower long-term mortality. Lack of association between ventilatory settings and survival may point to the importance of other variables than ventilation in the development of PGD.

Critical illness in children is not common. The acute stabilization and resuscitation of critically ill children remains challenging to even the most experienced operator. Cardio-respiratory illness represents the largest sub group of diseases causing critical illness and thus adds a layer of complexity and additional challenge to the safe intubation and establishment of effective ventilation of this group of children. Children have unique physiological and anatomical differences to adults, and present the team involved in their resuscitation and stabilization with challenges exaggerated by critical illness. The consideration of pathophysiological implications of disease and the equipment available during transport and retrieval from the roadside or non-specialist setting to pediatric intensive care, allows the clinician involved in resuscitation, stabilization and establishment of ventilation to employ targeted strategies to optimize ventilatory success. This review focuses on the types of ventilatory challenges that must be addressed when managing critically ill children in the local settings in which they present, and the resources available to optimize the outcome prior to and during transfer to a higher level of care.

Major complications associated with airway management are rare but often have serious consequences. Complications frequently result from failures in communication and teamwork. We performed a systematic review on the effect of simulation-based team training on patient outcomes, healthcare professionals' clinical performance and preparedness for airway management. We included studies with simulation-based team training in airway management as the educational intervention, using any comparator, outcome and design. Two authors independently selected articles and assessed risk of bias using the Medical Education Research Study Quality Instrument and Newcastle-Ottawa Scale-Education. We screened 1248 titles and evaluated 116 full-text articles. Twenty-two studies were included. The Kirkpatrick model for evaluation of training was used to organise outcomes. Four studies reported patient-centred outcomes (Kirkpatrick level 4), and three studies' outcomes related to healthcare professionals' clinical performance (Kirkpatrick level 3). The results were ambiguous and the studies had significant methodological limitations, making it difficult to draw conclusions on the effect of simulation-based team training. To describe preparedness for airway management, we used outcomes related to participants' attitudes or perceptions and outcomes related to knowledge or skills demonstrated in a test setting (Kirkpatrick level 2). Most studies reporting these outcomes were in favour of simulation-based team training, but were prone to bias. We consider the current evidence to be weak and recommend that future research should be based on randomised study designs and patient-centred outcomes.

The American Society of Anesthesiologists; All India Difficult Airway Association; European Airway Management Society; European Society of Anaesthesiology and Intensive Care; Italian Society of Anesthesiology, Analgesia, Resuscitation and Intensive Care, Learning, Teaching and Investigation Difficult Airway Group; Society for Airway Management; Society for Ambulatory Anesthesia; Society for Head and Neck Anesthesia; Society for Pediatric Anesthesia; Society of Critical Care Anesthesiologists; and the Trauma Anesthesiology Society present an updated report of the Practice Guidelines for Management of the Difficult Airway.

Background: High-flow nasal oxygen cannula (HFNC) and noninvasive mechanical ventilation (NIV) can prevent reintubation in critically ill patients. However, their efficacy in post-extubated sepsis patients remains unclear. The objective of this study was to compare the efficacy of HFNC vs. NIV to prevent reintubation in post-extubated sepsis patients.

Methods: We conducted a single-centre, prospective, open-labelled, randomised controlled trial at the medical intensive care unit of Siriraj Hospital, Mahidol University, Bangkok, Thailand. Sepsis patients who had been intubated, recovered, and passed the spontaneous breathing trial were enrolled and randomly assigned in a 1:1 ratio to receive either HFNC or NIV support immediately after extubation. The primary outcome was rate of reintubation at 72 h after extubation.

Results: Between 1st October 2017 and 31st October 2019, 222 patients were enrolled and 112 were assigned to the HFNC group and 110 to the NIV group. Both groups were well matched in baseline characteristics. The median [IQR] age of the HFNC group was 66 [50-77] vs. 65.5 [54-77] years in the NIV group. The most common causes of intubation at admission were shock-related respiratory failure (57.1% vs. 55.5%) and acute hypoxic respiratory failure (34.8% vs. 40.9%) in the HFNC and NIV groups, respectively. The duration of mechanical ventilation before extubation was 5 [3-8] days in the HFNC group vs. 5 [3-9] days in the NIV group. There was no statistically significant difference in the primary outcome: 20/112 (17.9%) in the HFNC group required reintubation at 72 h compared to 20/110 (18.2%) in the NIV group [relative risk (RR) 0.99: 95% confidence interval (CI) (0.70-1.39); P = 0.95]. The 28-day mortality was not different: 8/112 (7.1%) with HFNC vs. 10/110 (9.1%) with NIV (RR 0.88: 95% CI (0.57-1.37); P = 0.59).

Conclusions: Among sepsis patients, there was no difference between HFNC and NIV in the prevention of reintubation at 72 h after extubation. Clinical Trial Registration ClinicalTrials.gov Identifier: NCT03246893; Registered 11 August 2017; https://clinicaltrials.gov/ct2/show/NCT03246893?term=surat+tongyoo&draw=2&rank=3.

Background: Poor medical outcomes often result from series of minor events. The present study assessed events related to airway management to determine whether targeted changes to departmental strategies for airway management can reduce the incidence.

Methods: This prospective before-and-after study was performed with ethics committee approval and written informed consent from patients. Major and minor events related to airway management were prospectively recorded for 9 weeks. After implementation of changes to departmental strategies for airway management, events were again prospectively recorded over 9 weeks. Primary outcome was number of cases with events. Secondary outcomes were various predefined events.

Results: At study baseline, 3668 cases and at follow-up 3786 cases were assessed. Cases with events decreased from 566 (15.4%) to 433 (11.4%) (risk ratio [RR]=0.74; 95% confidence interval [CI], 0.66-0.83; P<0.01). As secondary outcomes, the following events decreased: Cormack-Lehane grade 3 or 4 (4.3-2.9%; RR=0.67; 95% CI, 0.52-0.85; P<0.01); difficult bag-mask ventilation (3.8-2.7%; RR=0.69; 95% CI, 0.54-0.89; P<0.01); hypoxaemia (3.8-2.9%; RR=0.75; 95% CI, 0.59-0.96; P=0.03); unplanned use of special equipment (3.2-2.0%; RR=0.62; (95% CI, 0.47-0.83; P<0.01); oesophageal intubation (1.3-0.8%; RR=0.61; 95% CI, 0.39-0.96; P=0.03); bleeding (0.8-0.2%; RR=0.30; 95% CI, 0.14-0.63; P<0.01); insufficient spontaneous breathing (0.3-0.0%; RR=0.09; 95% CI, 0.01-0.68; P<0.01); communication errors (0.1-0.0%; RR=0; 95% CI, 0-NA; P=0.03).

Conclusions: Implementation of changes to departmental strategies for airway management significantly reduced cases with events related to airway management. Analysis of events and implementation of strategies that specifically target identified issues might be key to improving airway management.
Clinical trial registration: NCT02743767.

Abstract
Background: Medical support for space exploration missions must prepare for severe medical events in conditions of microgravity. A key component to managing these events is techniques of airway management. The aim of the present trial is to compare airway management devices in simulated microgravity.

Methods: In this randomized cross-over trial (RCT), four different devices were compared under simulated microgravity conditions utilizing a neutrally buoyant free-floating underwater manikin and poolside in normal gravity (control group). The primary endpoint was the successful placement of the airway device. The secondary endpoints were the number of attempts and the duration of each attempt.

Results: A total of 20 participants performed placement of each device in both gravity conditions in an Airway mannequin. The fastest time to initial ventilation in simulated microgravity was possible with the laryngeal tube (18.9 ± 8 seconds) followed by laryngeal mask (20.1 ± 9 seconds). The I-gel® supraglottic airway device required substantially more time for successful insertion in simulated microgravity (35.4 ± 25 seconds) as did endotracheal tube intubation by direct laryngoscopy (70.4 ± 35 seconds). Simulated microgravity conditions prolonged time to initial ventilation by 3.3 seconds (LM), 3.9 seconds (LT), 19.9 seconds (I-gel) and 43.1 seconds (endotracheal intubation, ETI) when compared to poolside attempts in normogravity.

Conclusion: In simulated microgravity conditions, use of the laryngeal tube or laryngeal mask provided the quickest time to initial ventilation, without deliberate tethering of the mannequin and rescuer to a fixed surface. Endotracheal intubation required significantly longer procedure times and, thus, was considered insufficient for clinical use in microgravity.

The first step of the primary survey in the evaluation of a trauma patient is airway assessment. It must be assessed for patency to ensure adequate oxygenation and ventilation or a secure airway established with a cuffed tube placed in the trachea [advanced trauma life support (ATLS)]. Out-of-hospital personnel may provide some airway support and supplemental oxygen while applying other measures to prevent blood loss and assess the severity of trauma. However, the assessment of airway adequacy by a trained trauma airway manager should occur within seconds to minutes of hospital arrival.

Abstract
Background: Obstructive sleep apnea (OSA) has been found to be associated with difficult airway, although there is a paucity of prospective studies investigating thresholds of OSA severity with difficult airway outcomes. The aim of this study was to examine the association between OSA and difficult intubation or difficult mask ventilation. We also explored the utility of the Snoring, Tiredness, Observed apnea, high blood Pressure, Body mass index, Age, Neck circumference, and Gender (STOP-Bang) score for difficult airway prediction.

Methods: The Postoperative Vascular Complications in Unrecognized Obstructive Sleep Apnea (POSA) trial was an international prospective cohort study of surgical patients 45 years or older with one or more cardiac risk factor presenting for noncardiac surgery, with planned secondary analyses of difficult airway outcomes. Multivariable logistic regression analyses tested associations between OSA severity and predictors of difficult airway with difficult intubation or difficult mask ventilation. Overall, 869 patients without prior diagnosis of OSA were screened for OSA risk with the STOP-Bang tool, underwent preoperative sleep study, and had routine perioperative care, including general anesthesia with tracheal intubation. The primary outcome analyzed was difficult intubation, and the secondary outcome was difficult mask ventilation.

Results: Based on the sleep studies, 287 (33%), 324 (37%), 169 (20%), and 89 (10%) of the 869 patients had no, mild, moderate, and severe OSA, respectively. One hundred and seventy-two (20%) had a STOP-Bang score of 0-2 (low risk), 483 (55%) had a STOP-Bang score of 3-4 (intermediate risk), and 214 (25%) had a STOP-Bang score 5-8 (high risk). The incidence of difficult intubation was 6.7% (58 of 869), and difficult mask ventilation was 3.7% (32 of 869). Multivariable logistic regression demonstrated that moderate OSA (odds ratio [OR] = 3.26 [95% confidence interval {CI}, 1.37-8.38], adjusted P = .010) and severe OSA (OR = 4.05 [95% CI, 1.51-11.36], adjusted P = .006) but not mild OSA were independently associated with difficult intubation compared to patients without OSA. Relative to scores of 0-2, STOP-Bang scores of 3-4 and 5-8 were associated with increased odds of difficult intubation (OR = 3.01 [95% CI, 1.13-10.40, adjusted P = .046] and 4.38 [95% CI, 1.46-16.36, adjusted P = .014]), respectively. OSA was not associated with difficult mask ventilation, and only increasing neck circumference was found to be associated (adjusted P = .002).

Conclusions: Moderate and severe OSA were associated with difficult intubation, and increasing neck circumference was associated with difficult mask ventilation. A higher STOP-Bang score of 3 or more may be associated with difficult intubation versus STOP-Bang score of 0-2. Anesthesiologists should be vigilant for difficult intubation when managing patients suspected or diagnosed with OSA.

Abstract
Background: We examined the association between emergent postoperative tracheal intubation and the use of supraglottic airway devices (SGAs) vs tracheal tubes.

Methods: We included data from adult noncardiac surgical cases under general anaesthesia between 2008 and 2018. We only included cases (n=59 991) in which both airways were deemed to be feasible options. Multivariable logistic regression, instrumental variable analysis, propensity matching, and mediation analysis were used.

Results: Use of a tracheal tube was associated with a higher risk of emergent postoperative intubation (adjusted absolute risk difference [ARD]=0.80%; 95% confidence interval (CI), 0.64-0.97; P<0.001), and a higher risk of post-extubation hypoxaemia (ARD=3.9%; 95% CI, 3.4-4.4; P<0.001). The effect was modified by the use of non-depolarising neuromuscular blocking agents (NMBAs); mediation analyses revealed that 28.9% (95% CI, 14.4-43.4%; P<0.001) of the main effect was attributable to NMBA. Airway management modified the association of NMBA and risk of emergent postoperative intubation (Pinteraction=0.02). Patients managed with an SGA had higher odds of NMBA-associated reintubation compared to patients managed with a tracheal tube (adjusted odds ratio [aOR]=3.65, 95% CI, 1.99-6.67 vs aOR=1.68, 95% CI, 1.29-2.18 [P<0.001], respectively).

Conclusions: In patients undergoing procedures under general anaesthesia that could be managed with either SGA or tracheal tube, use of an SGA was associated with lower risk of emergent postoperative intubation. The effect can partly be explained by use of NMBAs. Use of NMBAs in patients with an SGA appears to increase the risk of emergent postoperative intubation.

Abstract
The potential aerosolised transmission of severe acute respiratory syndrome coronavirus-2 is of global concern. Airborne precaution personal protective equipment and preventative measures are universally mandated for medical procedures deemed to be aerosol generating. The implementation of these measures is having a huge impact on healthcare provision. There is currently a lack of quantitative evidence on the number and size of airborne particles produced during aerosol-generating procedures to inform risk assessments. To address this evidence gap, we conducted real-time, high-resolution environmental monitoring in ultraclean ventilation operating theatres during tracheal intubation and extubation sequences. Continuous sampling with an optical particle sizer allowed characterisation of aerosol generation within the zone between the patient and anaesthetist. Aerosol monitoring showed a very low background particle count (0.4 particles.l-1 ) allowing resolution of transient increases in airborne particles associated with airway management. As a positive reference control, we quantitated the aerosol produced in the same setting by a volitional cough (average concentration, 732 (418) particles.l-1 , n = 38). Tracheal intubation including facemask ventilation produced very low quantities of aerosolised particles (average concentration, 1.4 (1.4) particles.l-1 , n = 14, p < 0.0001 vs. cough). Tracheal extubation, particularly when the patient coughed, produced a detectable aerosol (21 (18) l-1 , n = 10) which was 15-fold greater than intubation (p = 0.0004) but 35-fold less than a volitional cough (p < 0.0001). The study does not support the designation of elective tracheal intubation as an aerosol-generating procedure. Extubation generates more detectable aerosol than intubation but falls below the current criterion for designation as a high-risk aerosol-generating procedure. These novel findings from real-time aerosol detection in a routine healthcare setting provide a quantitative methodology for risk assessment that can be extended to other airway management techniques and clinical settings. They also indicate the need for reappraisal of what constitutes an aerosol-generating procedure and the associated precautions for routine anaesthetic airway management.

Abstract
Airway simulators, or training manikins, are frequently used in research studies for device development and training purposes. This study was designed to determine the anatomic accuracy of the most frequently used low-fidelity airway training manikins. Computerised tomography scans and ruler measurements were taken of the SynDaver® , Laerdal® and AirSim® manikins. These measurements were compared with human computerised tomography (CT) scans (n = 33) from patients at the University of Michigan Medical Center or previously published values. Manikin measurements were scored as a percentile among the distribution of the same measurements in the human population and 10 out of 27 manikin measurements (nine measurements each in three manikins) were outside of two standard deviations from the mean in the participants. All three manikins were visually identifiable as outliers when plotting the first two dimensions from multidimensional scaling. In particular, the airway space between the epiglottis and posterior pharyngeal wall, through which airway devices must pass, was too large in all three manikins. SynDaver, Laerdal and AirSim manikins do not have anatomically correct static dimensions in relation to humans and these inaccuracies may lead to imprecise airway device development, negatively affect training and cause over-confidence in users.

Abstract
Background: Pediatric emergency front of neck airway guidelines recommend oxygenation via cannula cricothyroidotomy or tracheotomy.

Aim: The primary aim was to measure test lung pressures and volumes generated by cannula insufflation devices recommended for emergency front of neck airway compared with a pressure limit of 50 cm H2 O and volume limit of 20 ml/kg. The secondary aim was to calculate pressure and volume variability. The primary end point was test-lung expansion.

Method: Adult, child and infant airway models, each with three degrees of upper airway obstruction, were oxygenated using six cannula insufflation devices: 3-way stopcock, Rapid-O2 , Manujet, Enk oxygen flow modulator (OFM), Ventrain and self-inflating bags. Test lung pressures and volumes were recorded.

Results: Pressures and volumes from all devices were highly variable, despite oxygen flow calibration and strict adherence to oxygen insufflation protocols. With upper airway occlusion, pressures >50cm H2 0 were produced by Rapid-O2 and Enk-OFM in adult and infant lungs, 3-way stopcock in adult and child lungs and Manujet in all lung sizes. Ventrain produced acceptable pressures <35 cm H2 O in all models. Test lung volumes >20ml/kg were recorded in airway models with fully obstructed proximal airways using Rapid-O2 and Enk-OFM in infant lungs, and Manujet in all lung sizes. Rapid-O2 produced lung volumes >20ml/kg in the infant model with partially obstructed and open upper airways. Test lung volumes >20ml/kg were produced by the 3-way stopcock in adult, child and infant models. Insufflation was unsuccessful with the self-inflating bag. Ventrain produced acceptable volumes <7ml/kg in all airway models.

Conclusion: Rapid-O2 , Enk-OFM, Manujet and 3-way stopcock oxygenation devices produced highly variable and excessive airway pressures and volumes in models with obstructed upper airways. Self-inflating bag insufflation was unsuccessful. Ventrain was the only device that insufflated oxygen with acceptable pressures and volumes in adult, child and infant airway models with any degree of airway obstruction.

This Airway issue focuses on airway management across all academic subspecialties, adult and paediatric. The focus is on practical as well as innovative techniques for airway management inside and outside the operating room. Challenging patient populations and information disseminated to anaesthesiologists from other surgical subspecialties will be shared.

Resuscitation is a monthly international and interdisciplinary medical journal. The papers published deal with the aetiology, pathophysiology and prevention of cardiac arrest, resuscitation training, clinical resuscitation, and experimental resuscitation research, although papers relating to animal studies will be published only if they are of exceptional interest and related directly to clinical cardiopulmonary resuscitation. Papers relating to trauma are published occasionally but the majority of these concern traumatic cardiac arrest.

Resuscitation Plus, a companion title to the respected Resuscitation, is an open access quarterly international and interdisciplinary medical journal. The papers published deal with the aetiology, pathophysiology and prevention of cardiac arrest, resuscitation training and simulation, clinical resuscitation, and experimental resuscitation research. Animal studies relating to cardiopulmonary resuscitation and post-resuscitation and papers relating to traumatic cardiac arrest and haemorrhagic shock are encouraged. Systematic reviews, narrative reviews, scoping reviews, case reports and methods papers relating to cardiopulmonary resuscitation are also encouraged.