Patients scheduled for elective surgery requiring general anaesthesia and hospital admission were assessed for risk of obstructive sleep apnoea (OSA) using history, body mass index and upper airway examination to determine any relation between OSA risk and the rate of respiratory events after surgery. Anaesthesia and postoperative analgesia were at the discretion of the treating anaesthetist, who was made aware of any suspicion of OSA. Respiratory monitoring for apnoeas (central or obstructive), hypopnoeas and oxygen desaturations was continuous for a 12-hour period on the first postoperative night. We used automated analysis and visual scanning of respiratory recordings, but sleep stages were not assessed. Patients classified as OSA risk had more respiratory obstructive events per hour than controls (38±22 vs. 14±10) and an increased proportion of the 12-hour monitored period with oxygen saturation <90% (7±12% vs. 2±5% of the 12-hour period). Perioperative morphine dose was predictive of central apnoeas for both OSA risk and control patients (P=0.002). This study suggests that preoperative suspicion of OSA should lead to increased postoperative monitoring and efforts to minimise sedation and opioid dose. It also supports the routine use of supplemental oxygen with patient-controlled opioid analgesia.

1. Effects of the alpha2-adrenoceptor agonist dexmedetomidine on vasoconstrictor and heart rate (HR) responses to acute central hypovolaemia were studied in eight chronically instrumented rabbits. We compared intravenous (i.v.) and fourth ventricular (V4) dexmedetomidine (0.1-10 microg/kg) and the reversal of effects by the alpha2-adrenoceptor antagonist idazoxan and the opioid agonist alfentanil. 2. Gradual inflation of an inferior vena cava (IVC) cuff reduced cardiac index (CI) by 8%/min, with progressive vasoconstriction and increased HR. In control rabbits, at approximately 40% baseline CI, there was sudden decompensation with failure of vasoconstriction and a fall in mean arterial pressure (MAP). 3. Dexmedetomidine (i.v. and V4) reduced resting MAP and HR and caused an earlier decompensation during central hypovolaemia. Intravenous dexmedetomidine (3 and 10 microg/kg) also reduced the slope of the initial vasoconstrictor response and the maximum HR. 4. The effects of dexmedetomidine were reversed by the antagonist idazoxan, which prevented the decompensation phase. Intravenous alfentanil was also effective in restoring the vasoconstrictor response and delaying decompensation with hypovolaemia after dexmedetomidine. Combining dexmedetomidine with an opioid, such as alfentanil, may provide the benefit of reduced sympathetic tone without increased risk of cardiovascular collapse.

Pethidine requirements and verbal pain scores were recorded in 36 patients after cholecystectomy via subcostal incision. All patients also received 20 ml 0.5% bupivacaine with adrenaline 11200,000. Group 1 (12 patients) received unilateral intercostal nerve blocks. Interpleural catheters were inserted through the 8th intercostal space in the remaining patients; 12 received local anaesthetic via the catheter immediately after surgery (Group 2) and 12 were given local anaesthetic at three hours (Group 3). Small asymptomatic pneumothoraces were noted on chest X-ray in six of the 24 patients with interpleural catheters. Both types of local anaesthesia produced lower pain scores than pethidine alone (P < 0.05) with 25% of intercostal nerve blocks and 63% of interpleural catheters requiring no pethidine in the following three hours. The provision of catheter 'top-ups' between six and 18 hours after surgery also resulted in lower pain scores and a reduction in pethidine requirements (P < 0.05).