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Postoperative nausea and vomiting is a common adverse effect of anaesthesia. Although dozens of different anti-emetics are available for clinical practice, there is currently no comparative ranking of efficacy and safety of these drugs to inform clinical practice. We performed a systematic review with network meta-analyses to compare, and rank in terms of efficacy and safety, single anti-emetic drugs and their combinations, including 5-hydroxytryptamine 3 , dopamine-2 and neurokinin-1 receptor antagonists; corticosteroids; antihistamines; and anticholinergics used to prevent postoperative nausea and vomiting in adults after general anaesthesia. We systematically searched for placebo-controlled and head-to-head randomised controlled trials up to November 2017 (updated in April 2020). We assessed how trustworthy the evidence was using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) and Confidence In Network Meta-Analysis (CINeMA) approaches for vomiting within 24 h postoperatively, serious adverse events, any adverse event and drug class-specific side-effects. We included 585 trials (97,516 participants, 83% women) testing 44 single drugs and 51 drug combinations. The studies' overall risk of bias was assessed as low in only 27% of the studies. In 282 trials, 29 out of 36 drug combinations and 10 out of 28 single drugs lowered the risk of vomiting at least 20% compared with placebo. In the ranking of treatments, combinations of drugs were generally more effective than single drugs. Single neurokinin-1 receptor antagonists were as effective as other drug combinations. Out of the 10 effective single drugs, certainty of evidence was high for aprepitant, with risk ratio (95%CI) 0.26 (0.18-0.38); ramosetron, 0.44 (0.32-0.59); granisetron, 0.45 (0.38-0.54); dexamethasone, 0.51 (0.44-0.57); and ondansetron, 0.55 (0.51-0.60). It was moderate for fosaprepitant, 0.06 (0.02-0.21) and droperidol, 0.61 (0.54-0.69). Granisetron and amisulpride are likely to have little or no increase in any adverse event compared with placebo, while dimenhydrinate and scopolamine may increase the number of patients with any adverse event compared with placebo. So far, there is no convincing evidence that other single drugs effect the incidence of serious, or any, adverse events when compared with placebo. Among drug class specific side-effects, evidence for single drugs is mostly not convincing. There is convincing evidence regarding the prophylactic effect of at least seven single drugs for postoperative vomiting such that future studies investigating these drugs will probably not change the estimated beneficial effect. However, there is still considerable lack of evidence regarding safety aspects that does warrant investigation., (© 2020 The Authors. Anaesthesia published by John Wiley & Sons Ltd on behalf of Association of Anaesthetists.)

In the peri-operative period, dexamethasone is widely and effectively used for prophylaxis of postoperative nausea and vomiting. The objective of this meta-analysis was to assess the adverse effects of an incidental steroid load of dexamethasone in adult surgical patients. We searched in MEDLINE, Embase, the Cochrane Central Register of Controlled Trials and the Web of Science for randomised controlled trials comparing an incidental steroid load of dexamethasone with a control intervention in adult patients undergoing surgery. Two review authors independently screened studies for eligibility, extracted data and assessed all included studies for bias. Our primary outcomes were postoperative systemic or wound infection, delayed wound healing and glycaemic response within 24 h. We included 37 studies in this meta-analysis. The pooled results found no evidence that dexamethasone increased the risk of a postoperative wound infection, Peto OR (95%CI) 1.01 (0.80-1.27); 4603 participants, 26 studies; I² = 32%; moderate-quality evidence. Whether dexamethasone influenced wound healing was unclear due to the large confidence intervals, Peto OR (95%CI) 0.99 (0.28-3.43); 1072 participants, 8 studies; I² = 0%; low-quality evidence. Dexamethasone produced a mild increase in glucose levels among participants without diabetes during the first 12 h after surgery, mean difference (95%CI) 0.7 mmol.l -1 (0.3-1.2) 10 studies; 595 participants; I² = 50%; low-quality evidence. This article is an abridged version of a Cochrane Review., (© 2019 Association of Anaesthetists.)

Epidural volume extension, a modification of combined spinal-epidural anaesthesia, involves the epidural injection of saline in order to increase the spread of drugs given intrathecally. Results from individual studies have so far been contradictory and we aimed to gather the available evidence for this technique. We performed a systematic literature search for randomised, controlled trials comparing epidural volume extension after spinal injection with a control group without epidural injection in patients undergoing surgery. Conventional meta-analyses, trial sequential analyses and meta-regression were performed, with the Grading of Recommendations on Assessment, Development and Evaluation (GRADE) approach used to express reliability of outcome estimates. We included 15 studies with 1177 participants. Meta-analyses for the primary outcomes, such as maximum sensory height (6 studies, 274 participants, mean difference (MD) (95%CI) -0.59 (-1.24 to 0.07) dermatomes, low-quality evidence) and hypotension (10 studies, 683 participants, risk ratio (95%CI) 0.84 (0.66-1.07), low-quality evidence), did not differ significantly between the two treatment arms, but trial sequential analysis suggested insufficient evidence to be certain of these findings. Meta-regression suggested a volume-dependent effect, with higher volumes causing a higher spread of intrathecal drugs and a higher incidence of hypotension. A sub-group analysis indicated a pronounced effect on motor block recovery time when a lower anaesthetic dose plus epidural volume extension was compared with a higher anaesthetic dose without epidural volume extension, the MD (95%CI) being -66.75 (-76.0 to -57.5) min, with trial sequential analysis suggesting the evidence was sufficient to draw this conclusion. In trials using the same anaesthetic mixture in the epidural volume extension and the control groups, motor block recovery time did not differ between groups, with a MD (95%CI) of -1.06 (-5.48 to 3.36) min, although trial sequential analysis suggested insufficient evidence. In summary, there is not enough evidence to draw definite conclusions on the effect of epidural volume extension. The quality of the current evidence is low for both efficacy (maximum sensory height) and safety (hypotension). However, there may be a significantly shorter motor block recovery time when different anaesthetic mixtures are used in epidural volume extension and control groups; this warrants further investigation., (© 2017 The Association of Anaesthetists of Great Britain and Ireland.)

We aimed to assess the effectiveness of remifentanil used as intravenous patient-controlled analgesia for the pain of labour. We performed a systematic literature search in December 2015 (updated in December 2016). We included randomised, controlled and cluster-randomised trials of women in labour with planned vaginal delivery receiving patient-controlled remifentanil compared principally with other parenteral and patient-controlled opioids, epidural analgesia and continuous remifentanil infusion or placebo. The primary outcomes were patient satisfaction with pain relief and the occurrence of adverse events for mothers and newborns. We assessed risk of bias for each included study and applied the GRADE approach for the quality of evidence. We included total zero event trials, using a constant continuity correction of 0.01 and a random-effect meta-analysis. Twenty studies were included in the qualitative analysis; within these, 3713 participants were randomised and 3569 analysed. Most of our pre-specified outcomes were not studied in the included trials. However, we found evidence that women using patient-controlled remifentanil were more satisfied with pain relief than women receiving parenteral opioids (four trials, 216 patients, very low quality evidence) with a standardised mean difference ([SMD] 95%CI) of 2.11 (0.72-3.49), but were less satisfied than women receiving epidural analgesia (seven trials, 2135 patients, very low quality evidence), -0.22 (-0.40 to -0.04). Data on adverse events were sparse. However, the relative risk (95%CI) for maternal respiratory depression for patient-controlled remifentanil compared with epidural analgesia (three trials, 687 patients, low-quality evidence) was 0.91 (0.51-1.62). Compared with continuous intravenous infusion of remifentanil (two trials, 135 patients, low-quality evidence) no conclusion could be reached as all study arms showed zero events. The relative risk (95%CI) of Apgar scores less than 7 at 5 min after birth compared with epidural analgesia (five trials, 1322 participants, low-quality evidence) was 1.26 (0.62-2.57)., (© 2017 The Association of Anaesthetists of Great Britain and Ireland.)

The classic Laryngeal Mask Airway (cLMA), ProSeal Laryngeal Mask Airway (PLMA), Intubating Laryngeal Mask Airway (ILMA), Combitube (CT), Laryngeal Tube (LT) and tracheal intubation (TI) were compared in a manikin study. Nurses, anaesthetic nurses, paramedics, physicians and anaesthetists inserted the devices three times in a randomised sequence. Time taken for successful insertion, success rates and ease of insertion were evaluated. Anaesthetists performed tracheal intubation significantly faster than other healthcare professionals (p < 0.05). Insertion times for the cLMA, PLMA, LT and CT were not significantly different between the groups. Insertion of the CT, ILMA and TI was associated with a significant learning effect in all groups. This was not observed with the cLMA, PLMA or LT. All non-anaesthetists were able to insert the cLMA, PLMA and LT within two attempts with a > 90% success rate on the first attempt. The ILMA and TI were the only devices where more than one subject experienced some difficulty in insertion. The cLMA, PLMA and LT should be evaluated for use in situations where only limited airway training is possible.

Optical laryngoscopes have been developed to facilitate difficult airway management. The Airtraq is a single-use device and the GlideScope is reusable. In this study, the Airtraq and the Glidescope were compared in 60 ASA I-III patients with tumours of the upper airway undergoing direct endoscopic microlaryngoscopy. Patients were randomly assigned to the Airtraq or the Glidescope group and the Cormack and Lehane grade was assessed by Macintosh laryngoscopy prior to tracheal intubation. There were no differences in tracheal intubation success rates or duration of intubation attempts between both devices. The Cormack and Lehane grade was improved in 77% and 82% of cases in the Airtraq and Glidescope group, respectively. Blood traces on the device and traumatic pharyngeal lesions were found more frequently in the Airtraq group. The Airtraq and Glidescope laryngoscopes are valuable tools for the management of patients with potentially difficult airways with the Glidescope appearing to be less traumatic.

Ondansetron is widely believed to prevent postoperative vomiting more effectively than nausea. We analysed data from 5161 patients undergoing general anaesthesia who were randomly stratified to receive a combination of six interventions, one of which was 4 mg ondansetron vs placebo. For the purpose of this study a 20% difference in the relative risks for the two outcomes was considered clinically relevant. Nausea was reduced from 38% (969/2585) in the control to 28% (715/2576) in the ondansetron group, corresponding to a relative risk of 0.74, or a relative risk reduction of 26%. Vomiting was reduced from 17% (441/2585) to 11% (293/2576), corresponding to a relative risk of 0.67, or a relative risk reduction of 33%. The relative risks of 0.67 and 0.74 were clinically similar and the difference between them did not reach statistical significance. We thus conclude that ondansetron prevents postoperative nausea and postoperative vomiting equally well.

We hypothesised that intramuscular halothane injection increases local Pco(2) concentrations in malignant hyperthermia susceptible (MHS) but not in non-susceptible (MHN) individuals. Pco(2) probes with attached microtubing catheters for halothane injection were placed into the lateral vastus muscle of eight MHS and eight MHN probands. Following equilibration, a single bolus of 200 microl halothane 5 and 6 vol% was injected. Pco(2) was measured spectrophotometrically. Baseline Pco(2) concentrations were similar between groups. Maximum Pco(2) and maximum rate of Pco(2) increase was significantly enhanced by halothane 5 and 6 vol% in MHS compared to MHN probands. Systemic haemodynamic and metabolic parameters did not differ between both groups. Local halothane application induces a hypermetabolic reaction with a significant Pco(2) increase in MHS compared to MHN probands, indicating a susceptibility to malignant hyperthermia. Intramuscular halothane injection with Pco(2) measurement seems to be a suitable method for the development of a minimally invasive metabolic test to diagnose malignant hyperthermia susceptibility.

It is not known whether dexamethasone increases the effectiveness of anti-emetics when given to treat postoperative nausea and vomiting (PONV). In a randomised study, 242 patients who were experiencing PONV received dolasetron and placebo, haloperidol and placebo, dolasetron and dexamethasone, or haloperidol and dexamethasone. The results from 228 patients were suitable for analysis. PONV recurred significantly less frequently in patients treated with additional dexamethasone (33%) than in patients treated without additional dexamethasone (51%). The combination of dexamethasone with dolasetron or dexamethasone with haloperidol is superior to dolasetron or haloperidol alone for the treatment of PONV.

Although site of surgery and previous occurrence of postoperative nausea and vomiting are often used to decide whether prophylactic anti-emetic drugs are indicated, the value of these predictors is unclear. We compared these two risk factors against a simplified four-factor risk score. We analysed data from 1566 adult inpatients who received balanced anaesthesia without prophylactic anti-emetics. Sensitivity, specificity, predictive value and area under the receiver operating characteristic curve were used to quantify predictive properties. Nausea and vomiting occurred in 600 (38.3%) patients within 24 h. Sensitivity and specificity were, respectively, 47% and 59% for surgical site; 47% and 70% for history of postoperative nausea and vomiting; and 58% and 70% for risk score with three or more factors. The area under the curve for surgical site was 0.53 (95% CI 0.50-0.56); that for patient's history was 0.58 (95% CI 0.56-0.61) while for risk score it was 0.68 (95% CI 0.66-0.71; P < 0.001). Prediction using surgical site or patient's history alone was poor while the simplified risk score provided clinically useful sensitivity and specificity.

Postanaesthetic shivering is a frequent complication following general anaesthesia. The aim of this study was to compare the effectiveness of three doses of nefopam with clonidine and placebo in the prevention of postanaesthetic shivering. We studied 371 patients undergoing abdominal or orthopaedic surgery. Patients were allocated to one of five groups: Group A (n = 73) received 0.2 mg x kg(-1) nefopam, Group B (n = 75) 0.1 mg x kg(-1) nefopam, Group C (n = 76) 0.05 mg x kg(-1) nefopam, Group D (n = 73) 1.5 microg x kg(-1) clonidine, and Group E (n = 74) saline 0.9% as placebo. We found a significant reduction in the incidence of shivering in Group A compared to Group C and clonidine as well as to the placebo group. All active treatments reduced the incidence and the severity of shivering compared to placebo. At 5 min postoperatively clonidine-treated patients showed a significant decrease in MAP and a significantly lower Aldrete score compared to all other groups. No haemodynamic or sedative adverse events were observed in the nefopam-treated patients. The results of our study indicate that nefopam (0.2 mg x kg(-1)) is superior to clonidine (1.5 microg x kg(-1)) in the prophylaxis of postanaesthetic shivering and not accompanied by sedative or haemodynamic side-effects.