[Combined intrathecal morphine and bupivacaine for elective post-caesarean pain]

Intrathecal morphine is widely used for analgesia following cesarean section in Europe and North America. In Japan analgesic method of intrathecal morphine was admitted to the insurance adjustment and it is necessary to study optimal dose of the morphine.

We examined 72 parturients undergoing elective cesarean section under spinal anesthesia. Patients were randomly assigned to receive, in a double-blind fashion, either morphine 0.05 mg, morphine 0.1 mg, morphine 0.2 mg, or saline in 0.1 ml (control group) mixed with the bupivacaine for cesarean section. A patient-controlled analgesia (PCA) device for intravenous morphine provided free access to additional analgesics for 24 hr.

Total amount of morphine during postoperative first 24 hrs using PCA was significantly higher in the control group than in 0.1 and 0.2 mg groups. There were no significant differences between the control group and the morphine groups with respect to nausea. The incidence of pruritus was significantly higher in 0.1 and 0.2 mg groups than in the control group. In one patient in 0.2 mg group, oxygen saturation decreased below 95% postoperatively, but it was improved by oxygen inhalation.

It is concluded that intrathecal morphine 0.1 mg gives effective analgesia with minimum side effects after cesarean section for the Japanese patients.