Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Ontario Ministry of Health and Long-Term Care, Ontario Ministry of Research, Innovation and Science, UK National Institute of Academic Anaesthesia, UK Clinical Research Collaboration, Australian and New Zealand College of Anaesthetists, and Monash University.

Response surfaces can describe anesthetic interactions, even those between agonists, partial agonists, competitive antagonists, and inverse agonists. Application of response-surface methodology permits characterization of the full concentration-response relation and therefore can be used to develop practical guidelines for optimal drug dosing.

Objective To clinically evaluate a new patented multimodal system (SAFERSleep) designed to reduce errors in the recording and administration of drugs in anaesthesia. Design Prospective randomised open label clinical trial.Setting Five designated operating theatres in a major tertiary referral hospital.Participants Eighty nine consenting anaesthetists managing 1075 cases in which there were 10 764 drug administrations.Intervention Use of the new system (which includes customised drug trays and purpose designed drug trolley drawers to promote a well organised anaesthetic workspace and aseptic technique; pre-filled syringes for commonly used anaesthetic drugs; large legible colour coded drug labels; a barcode reader linked to a computer, speakers, and touch screen to provide automatic auditory and visual verification of selected drugs immediately before each administration; automatic compilation of an anaesthetic record; an on-screen and audible warning if an antibiotic has not been administered within 15 minutes of the start of anaesthesia; and certain procedural rules-notably, scanning the label before each drug administration) versus conventional practice in drug administration with a manually compiled anaesthetic record. Main outcome measuresPrimary: composite of errors in the recording and administration of intravenous drugs detected by direct observation and by detailed reconciliation of the contents of used drug vials against recorded administrations; and lapses in responding to an intermittent visual stimulus (vigilance latency task). Secondary: outcomes in patients; analyses of anaesthetists' tasks and assessments of workload; evaluation of the legibility of anaesthetic records; evaluation of compliance with the procedural rules of the new system; and questionnaire based ratings of the respective systems by participants. ResultsThe overall mean rate of drug errors per 100 administrations was 9.1 (95% confidence interval 6.9 to 11.4) with the new system (one in 11 administrations) and 11.6 (9.3 to 13.9) with conventional methods (one in nine administrations) (P=0.045 for difference). Most were recording errors, and, though fewer drug administration errors occurred with the new system, the comparison with conventional methods did not reach significance. Rates of errors in drug administration were lower when anaesthetists consistently applied two key principles of the new system (scanning the drug barcode before administering each drug and keeping the voice prompt active) than when they did not: mean 6.0 (3.1 to 8.8) errors per 100 administrations v 9.7 (8.4 to 11.1) respectively (P=0.004). Lapses in the vigilance latency task occurred in 12% (58/471) of cases with the new system and 9% (40/473) with conventional methods (P=0.052). The records generated by the new system were more legible, and anaesthetists preferred the new system, particularly

A large number of postoperative pulmonary outcome measures have been used, but most are poorly defined. Our four recommended outcome measures include a new definition of postoperative pulmonary complications, incorporating an assessment of severity. These definitions will meet the needs of most clinical effectiveness trials of treatments to improve postoperative pulmonary outcomes.

; for the Postoperative Vascular Complications in Unrecognized Obstructive Sleep Apnea (POSA) Study Investigators IMPORTANCE Unrecognized obstructive sleep apnea increases cardiovascular risks in the general population, but whether obstructive sleep apnea poses a similar risk in the perioperative period remains uncertain. OBJECTIVES To determine the association between obstructive sleep apnea and 30-day risk of cardiovascular complications after major noncardiac surgery. DESIGN, SETTING, AND PARTICIPANTS Prospective cohort study involving adult at-risk patients without prior diagnosis of sleep apnea and undergoing major noncardiac surgery from 8 hospitals in 5 countries between January 2012 and July 2017, with follow-up until August 2017. Postoperative monitoring included nocturnal pulse oximetry and measurement of cardiac troponin concentrations. EXPOSURES Obstructive sleep apnea was classified as mild (respiratory event index [REI] 5-14.9 events/h), moderate (REI 15-30), and severe (REI >30), based on preoperative portable sleep monitoring. MAIN OUTCOMES AND MEASURES The primary outcome was a composite of myocardial injury, cardiac death, heart failure, thromboembolism, atrial fibrillation, and stroke within 30 days of surgery. Proportional-hazards analysis was used to determine the association between obstructive sleep apnea and postoperative cardiovascular complications. RESULTS Among a total of 1364 patients recruited for the study, 1218 patients (mean age, 67 [SD, 9] years; 40.2% women) were included in the analyses. At 30 days after surgery, rates of the primary outcome were 30.1% (41/136) for patients with severe OSA, 22.1% (52/235) for patients with moderate OSA, 19.0% (86/452) for patients with mild OSA, and 14.2% (56/395) for patients with no OSA. OSA was associated with higher risk for the primary outcome

SummaryTwo-hundred and forty incidents of vomiting/regurgitation and aspiration were reported to the Anaesthetic Incident Monitoring Study database consisting of 5000 reports. Of these, 133 cases of aspiration were recorded. Passive regurgitation occurred three times more commonly than active vomiting. Aspiration was reported twice as often in elective compared with emergency surgery, with 56% of incidents taking place during induction of anaesthesia. Anti-aspiration prophylaxis was prescribed in 14% of patients who subsequently aspirated; however, the majority of cases had at least one predisposing factor for regurgitation, vomiting or aspiration evident peri-operatively. While a major immediate physiological disturbance was common, long-term morbidity was not. Death ensued in five cases, all of whom had significant co-morbidities. Factors reported as contributing to the incident included error of judgement and fault of technique, while clinical experience and anaesthetic assistance tended to minimise the incident. Aspiration remains an important anaesthetic-related morbidity. The application of simple guidelines may have prevented the incident in 60% of all cases of aspiration. Ensuring airway security may be as important as chemoprophylaxis in its prevention.

SummaryEight hundred and ninety-six incidents relating to drug error were reported to the Australian Incident Monitoring Study. Syringe and drug preparation errors accounted for 452 (50.4%) incidents, including 169 (18.9%) involving syringe swaps where the drug was correctly labelled but given in error, and 187 (20.8%) due to selection of the wrong ampoule or drug labelling errors. The drugs most commonly involved were neuromuscular blocking agents, followed by opioids. Equipment misuse or malfunction accounted for a further 234 (26.1%) incidents; incorrect route of administration 126 (14.1%) incidents; and communication error 35 (3.9%) incidents. The outcomes of these events included minor morbidity in 105 (11.7%), major morbidity in 42 (4.7%), death in three (0.3%) and awareness under anaesthesia in 40 (4.4%) incidents. Contributing factors included inattention, haste, drug labelling error, communication failure and fatigue. Factors minimising the events were prior experience and training, rechecking equipment and monitors capable of detecting the incident. The information gained suggests areas where improved guidelines are required to reduce the incidence of drug error. Further research is required into the effectiveness of preventive strategies.

We have studied interactions between i.v. propofol and midazolam for induction of anaesthesia in 200 unpremedicated female patients undergoing elective gynaecological surgery. Using end-points of "hypnosis" (loss of response to verbal command) and "anaesthesia" (loss of response to a 5-s transcutaneous tetanic stimulus), we determined dose-response curves for propofol and midazolam alone and in combination. For hypnosis, synergistic interaction was found (P less than 0.01), the combination having 1.44 times the potency of the individual agents. Although midazolam failed to produce anaesthesia in the dose range used, the dose of propofol required to produce anaesthesia was reduced by 52% in the presence of midazolam (P less than 0.01). The reduction in arterial pressure at induction was the same for the combination as for the individual agents. The cause of the synergism was not clear, but may have been interaction at CNS GABAA receptors.