The addition of epinephrine enhances postoperative analgesia by intrathecal morphine

To investigate whether the addition of epinephrine would enhance postoperative pain relief by intrathecal morphine, we studied 36 patients scheduled to have spinal anesthesia for gynecologic surgery. Patients were randomly allocated to one of three groups: the first received epinephrine 0.12 mg, morphine 0.2 mg, and hyperbaric tetracaine 12 mg intrathecally (EMT group, n = 11); the second received morphine 0.2 mg and hyperbaric tetracaine 12 mg intrathecally (MT group, n = 13); and the third received epinephrine 0.12 mg and hyperbaric tetracaine 12 mg intrathecally (ET group, n = 12). The time to the first request for supplemental analgesics was longest (2182 +/- 251 min, mean +/- SEM) and the injection number of supplemental analgesics was least in the EMT group (P < 0.05). The percentage of patients who received supplemental analgesics in the EMT group (45.5%) was less than the other two groups (P < 0.05). Six patients in the EMT group and one in the MT group needed no additional analgesics during 48 h (P < 0.05 versus the MT and ET groups). The visual analog scale (VAS) pain score was larger in the ET group than the EMT group (P < 0.05), but was similar in the EMT and MT groups. There were no differences among groups in the incidence of nausea and pruritus. Our data show that the addition of epinephrine enhances postoperative analgesia by intrathecal morphine without increasing the incidence of adverse effects as compared with intrathecal morphine alone.