Perioperative medicine: Overview

Abstract
Ketamine is an N-methyl-d-aspartate receptor antagonist approved for use in anaesthesia, with analgesic properties. Despite publication of numerous trials and expert guidelines on its use for pain management, administration of ketamine as part of multimodal perioperative analgesia remains 'off-label'. We conducted an online, prospective survey of ANZCA Fellows, exploring current prescribing practices of intravenous ketamine for perioperative analgesia. We surveyed 2000 Fellows and received 806 responses. The factors mostly likely to influence their administration of perioperative ketamine included pre-existing chronic pain, and heavy or multiple opioid use by patients preoperatively. Amongst respondents, less senior anaesthetists and those working in public hospitals were more likely to administer intraoperative ketamine. The surgical procedures most likely to result in ketamine administration intraoperatively were open pelvic/abdominal, thoracic and major spinal surgery, where ketamine administration was likely practice for the majority of respondents, with typical loading doses that ranged widely. The commonest choices of intraoperative loading dose were between 0.2 mg kg-1 and 0.6 mg kg-1. The commonest choice of intraoperative and postoperative infusion rate was in the range of 0.1-0.2 mg kg-1 h-1. Postoperative ketamine infusion was most commonly prescribed as third-line or rescue analgesia. The majority of respondents thought it either 'likely' or 'very likely' ketamine would reduce postoperative chronic pain after thoracic surgery, but not in other surgical categories. Our findings suggest that off-label perioperative administration of ketamine at analgesic dose ranges is routine or common practice in major surgery for a majority of specialist anaesthetists in Australia and New Zealand.

Abstract
Background: Individuals with neurodegenerative disorders are often provided the same perioperative care as unaffected peers, even though unidentified diminished preoperative "brain health" worsens surgical outcomes. We summarize the implementation and standardized data from a phased preoperative cognitive assessment consisting of screening tests administered by clinic staff and, on a failed screening, an immediate neuropsychological assessment from licensed neuropsychologists.

Methods: The present observational study used deidentified patient data provided via an honest broker over 2 years. The data included patients aged 65 or older at the time of treatment who were triaged for an in-person preoperative clinic visit, excluding those patients who were scheduled for orthopedic surgery. The cognitive screening assessed education, frailty, clock-drawing-test to command and copy conditions, and 3-word registration and recall. The neuropsychological evaluation involved 90-minute assessments with interviews, cognitive testing, interpretation, and recommendations to the perioperative care team. Standardized data from general cognition, attention, and memory metrics are shown for this current report.

Results: Of the 14,795 patients eligible for cognitive screening, 83.1% underwent screening, identifying 22.7% with atypical cognitive performance. Patients successfully screened were more often white (87.8% vs 78.4%; P < .0001), married (61.2% vs 57.9%; P < .0001), and less frail (nonfrail: 45.6% vs 20.5%; P < .0001). Of the 2790 patients referred for the comprehensive assessment, 48.9% completed the neuropsychological evaluation. Referred patients were older (74.6 ± 6.5 vs 72.9 ± 5.7 yrs; P < .0001), less educated (13.2 ± 2.9 vs 14.1 ± 2.9 yrs; P < .0001), less likely married (58.1% vs 62.8%; P < .0002), more frail (frail: 24.6% vs 16.5%; P < .0001), more likely to live in socioeconomically-deprived geographic regions (52.0% vs 47.7%; P < .0001), and had a 50% greater 1-year mortality than nonreferred patients (P < .0001). Patients who showed no impairment or had only memory impairment on the neuropsychological examination were less frail (nonfrail: 45.5% vs 30.6%; P < .0001) and only half as likely to have a canceled surgery than those who exhibited attention or combined attention and memory impairment (P = .0002).

Conclusions: Findings highlight how preoperative anesthesiology and neuropsychology teams can provide cognitive screening with referrals to brain health exams, and underscore the severity of unmet cognitive health care needs in older patients electing surgery.

Abstract
Purpose: Postoperative nausea and/or vomiting (PONV/POV) following tonsillectomy occurs in up to 89% of children without antiemetic prophylaxis. Prior systematic reviews have not evaluated the relative efficacy of ondansetron and metoclopramide for PONV/POV, including their adverse effects.

Methods: A systematic search was conducted of five databases from their inceptions to June 19, 2024. Inclusion criteria were randomized controlled trials (RCTs) comparing ondansetron and metoclopramide in pediatric patients undergoing tonsillectomy or adenotonsillectomy. The primary outcome was incidence of PONV/POV. Secondary outcomes were length of hospital stay (LOS) and adverse events including postoperative extrapyramidal reactions and delayed hospital readmissions. Pooled risk ratios (RRs) or mean differences (MDs) and 95% confidence intervals (CIs) were calculated using random-effects meta-analysis. Adjusted RRs were calculated using random-effects meta-regression. Risk of bias and certainty of evidence were assessed using Cochrane RoB 2 and GRADE, respectively. This study was registered in PROSPERO (42,024,499,702).

Results: Five RCTs met all inclusion criteria, consisting of 861 patients. Ondansetron significantly reduced risk of PONV/POV by almost 50% (RR 0.48 95% CI 0.31-0.75, moderate quality evidence), compared to metoclopramide. Intraoperative opioid dose did not impact the RR. Ondansetron also significantly shortened LOS (MD - 26.92 min 95% CI - 47.24 min to - 6.60 min, moderate quality evidence). Only two RCTs addressed readmission rates or extrapyramidal reactions, although no events occurred in either study.

Conclusion: Ondansetron is more effective than metoclopramide for PONV/POV prophylaxis, decreasing the risk of PONV/POV as well as LOS. Continued surveillance for adverse effects may be recommended when using either medication.