Comparison of the effectiveness of different regimens of epidural analgesia in postcesarean subjects experiencing pruritus

Background: Epidural anesthesia is widely used in the obstetric setting for providing not only labor pain relief, but also surgical analgesia for cesarean section and postoperative pain relief. However, the side effect of pruritus is of great concern for its high occurrence rate. The aim of our study was to compare and analyze the effectiveness of different regimens of epidural morphine analgesia for postcesarean section patients experiencing pruritus. Methods: We had retrospectively studied from June 2003 to April 2004 144 subjects undergoing cesarean section who agreed to accept postoperative pain relief via epidural route. Visual analogue scales (VAS) were compared between subjects not experiencing pruritus (Group I) and subjects experiencing pruritus (Group II) with modified regimens. Results: Thirty six subjects (Group II) out of 144 patients (25%) suffered from pruritus. Six different regimens were prescribed by anesthesiologists in these subjects. The characteristic of most different regimens was to reduce the dose of morphine from 2 mg twice per day to 0.5-1 mg twice per day with or without adding local anesthetics. All the subjects were satisfied as regards pain relief, except seven subjects who refused to receive epidural morphine again after appearance of pruritus. Conclusions: The incidence of pruritus caused by 2 mg epidural morphine in our population was about 25%. Once pruritus occurred, a single bolus of intravenous 30 mg diphenhydramine followed by reducing the epidural morphine dose to 0.5 to 1 mg morphine with or without low dose local anesthetics twice a day not only lessened the pruritus in a satisfactory manner but also provided a sufficient pain relief as effective as 2 mg morphine twice a day as assessed by VAS.