Background: The aim of this post hoc analysis of a large cohort study was to evaluate the association between night-time surgery and the occurrence of intraoperative adverse events (AEs) and postoperative pulmonary complications (PPCs). Methods: LAS VEGAS (Local Assessment of Ventilatory Management During General Anesthesia for Surgery) was a prospective international 1-week study that enrolled adult patients undergoing surgical procedures with general anaesthesia and mechanical ventilation in 146 hospitals across 29 countries. Surgeries were defined as occurring during 'daytime' when induction of anaesthesia was between 8:00 AM and 7:59 PM, and as 'night-time' when induction was between 8:00 PM and 7:59 AM. Results: Of 9861 included patients, 555 (5.6%) underwent surgery during night-time. The proportion of patients who developed intraoperative AEs was higher during night-time surgery in unmatched (43.6% vs 34.1%; P<0.001) and propensity-matched analyses (43.7% vs 36.8%; P¼0.029). PPCs also occurred more often in patients who underwent night-time surgery (14% vs 10%; P¼0.004) in an unmatched cohort analysis, although not in a propensity-matched analysis (13.8% vs 11.8%; P¼0.39). In a multivariable regression model, including patient characteristics and types of surgery and anaesthesia, night-time surgery was independently associated with a higher incidence of intraoperative AEs (odds ratio: 1.44; 95% confidence interval: 1.09e1.90; P¼0.01), but not with a higher incidence of PPCs (odds ratio: 1.32; 95% confidence interval: 0.89e1.90; P¼0.15). Conclusions: Intraoperative adverse events and postoperative pulmonary complications occurred more often in patients undergoing night-time surgery. Imbalances in patients' clinical characteristics, types of surgery, and intraoperative management at night-time partially explained the higher incidence of postoperative pulmonary complications, but not the higher incidence of adverse events. Clinical trial registration: NCT01601223.

Intra- and post-operative analgesic effects of pre-operative administration of carprofen were investigated in 16 medetomidine-premedicated dogs undergoing elective ovariectomy. Dogs were randomly allocated into carprofen (n=8; 4 mg/kg, intramuscularly) or placebo group (n = 8). After medetomidine (1000 [xg/m2, intramuscularly) premedication, they were induced with propofol (1 mg/kg, intravenously) and maintained with isoflurane (FE'ISO 1.0 %) in 100% oxygen. During anaesthesia, the analgesia was assessed in terms of changes in heart rate, respiratory rate and arterial blood pressure as a response to the surgery. Assessments of post-operative sedation (simple numerical rating scale) and pain (multifactorial pain scale) were made at 15 minutes, 30 minutes, 1,2,3, 4, 5, and 6 hours after the surgery. In addition, pulse rate, respiratory rate and body temperature were measured at the same time. During anaesthesia, lower heart rate, respiratory rate and mean arterial blood pressure and higher tidal volume of respiration were observed in the carprofen group. Post-operative pain score was relatively low in both groups of dogs, however it was higher, but not significantly, in the placebo group. There was no difference between the groups in terms of respiratory and pulse rate after surgery. The post-operative sedation score was higher in the placebo group only in the early post-operative period most probably due to misinterpretation of pain behaviour. Carprofen together with other anaesthetic drugs provided sufficient intra-operative analgesia only until major painful surgical stimulus occurred, after which analgesia had to be supplemented with a subanaesthetic dose of ketamine. Comparing to that analgesia was insufficient in the placebo group throughout the procedure. The post-operative pain scoring system was probably not sensitive enough to detect the differences between the groups; however, the effects of other drugs that extended in the post-operative period may be responsible for a low post­operative pain score in both groups of dogs

No abstract