The effect of a low-dose naloxone infusion on the incidence of respiratory depression after intrathecal morphine administration for major open hepatobiliary surgery: a randomised controlled trial.

Intrathecal morphine is an analgesic option for major hepatopancreaticobiliary procedures but is associated with a risk of respiratory depression. We hypothesised that a postoperative low-dose naloxone infusion would reduce the incidence of respiratory depression without an increase in pain scores. Patients scheduled for major open hepatopancreaticobiliary surgery and who were receiving 10 µg.kg-1 intrathecal morphine were eligible for inclusion. Patients were allocated randomly to receive a postoperative infusion of naloxone 5 µg.kg-1 .h-1 (naloxone group) or saline at an identical infusion rate (control group) until the morning after surgery. Clinicians, nursing staff and patients were blinded to group allocation. The primary outcome measure was the incidence of respiratory depression (respiratory rate < 10 breaths.min-1 and/or oxygen saturation < 90%). Secondary outcome measures included: arterial partial pressure of carbon dioxide; pain score; requirement for supplemental analgesic; and incidence of nausea and vomiting, pruritus and sedation. In total, data from 95 patients (48 in the naloxone group and 47 in the control group) were analysed. The incidence of respiratory depression was lower in the naloxone group compared with the control group (10/48 vs. 21/47 patients, respectively; p = 0.037, relative risk 0.47 (95%CI 0.25-0.87). Maximum pain scores were greater for patients allocated to the naloxone group compared with control (median 5 (95%CI 4-6) vs. 4 (95%CI 2-4), respectively; p < 0.001). A low-dose naloxone infusion decreases the incidence of respiratory depression following intrathecal morphine administration in patients having major hepatopancreaticobiliary surgery at the expense of a small increase in postoperative pain.

Volatile anaesthesia during cardiopulmonary bypass.

Since its inception, administering and ensuring anaesthesia during cardiopulmonary bypass has been challenging. Partly because of the difficulty of administering volatile agents during cardiopulmonary bypass, total intravenous anaesthesia has been a popular technique used by cardiac anaesthetists in the last two decades. However, the possibility that volatile agents reduce mortality and the incidence of myocardial infarction by preconditioning the myocardium has stimulated a resurgence of interest in their use for cardiac anaesthesia. The aim of this review is to provide an overview of the administration of volatile anaesthetic agents during cardiopulmonary bypass for the maintenance of anaesthesia and to address some of the practical issues that are involved in doing so.