Effects of sub-hypnotic doses of propofol on the side effects of intrathecal morphine.

We have studied the effect of propofol on the side effects associated with intrathecal morphine in 40 patients undergoing major arthroplasty. Patients received spinal anaesthesia with plain 0.5% bupivacaine 20 mg mixed with preservative-free morphine 0.3 mg. Before injection of the local anaesthetic, the patients were allocated randomly to receive either a bolus dose of propofol 10 mg followed by an infusion of 30 mg/24 h or equal volumes of 10% Intralipid (control group). The number of patients without postoperative nausea and vomiting (PONV) was similar in both groups. However, the incidence of nausea and vomiting was lower in the propofol (13 and 22, respectively) than in the control (34 and 36) group (P < 0.01 and P < 0.05, respectively). Severe vomiting episodes were less frequent in the propofol group (1 vs 11; P < 0.05). Four patients in the propofol group and 12 patients in the control group had itching (P < 0.05). The incidence of urinary retention was similar in both groups. There was no additional sedation attributable to propofol. In conclusion, sub-hypnotic doses of propofol protected significantly against itching and had a modest effect on PONV after intrathecal morphine.