The addition of 0.2 mg subarachnoid morphine to hyperbaric bupivacaine for cesarean delivery: a prospective study of 856 cases.

In an effort to determine the incidence of respiratory depression and other side effects of subarachnoid morphine, we conducted the following prospective study in a large number (856) of young female patients undergoing cesarean delivery in one hospital. During the period from July 1987 to January 1989, patients receiving subarachnoid hyperbaric bupivacaine combined with 0.2 mg preservative-free morphine were included. They were continuously monitored for 24 hours using a pulse oximeter. For 24 hours, the vital signs, including respiratory rate every hour, and the side effects, including pruritus, nausea, and vomiting, were recorded. The need for analgesia and the total dose of opioids during the first 24 hours were documented. Our results showed that respiratory depression (SaO2 less than or equal to 85% and/or respiratory rate ten breaths per minute or less) occurred in eight patients, all of whom were markedly obese. Fifty-eight percent of the patients did not require analgesics for 24 hours. In those requiring an added opioid, the dose was (9.1 +/- 0.5 mg morphine, mean +/- SEM). Eighty-five percent of the patients were satisfied with the postoperative analgesia. Six percent were dissatisfied due to the side effects, i.e., pruritus, nausea and/or vomiting. Nine percent were dissatisfied with the pulse oximeter because it caused false alarms and limited their mobility.