[Effect of intrathecal administration of opioid on minimum alveolar concentration and postoperative pain relief--a comparison of morphine and buprenorphine].

Intrathecal morphine (Mor) exerts potent analgesic effect and decreases anesthetic requirement. However, morphine was reported to have various uncomfortable side effects, and buprenorphine (BPN) is considered as an alternative opioid. The aim of this study was to investigate the effect of intrathecal BPN and Mor on the MAC of halothane and the relief of postoperative pain. The result shows that the MAC of halothane decreases dose dependently both in the BPN and Mor groups. The decrease in halothane MAC with 0.05 mg intrathecal BPN was equipotent with the intrathecal administration of 0.5 mg Mor. Adequate postoperative analgesia and severe pruritus were observed in the 0.5 mg Mor group. The intrathecal administration of 0.05 mg and 0.075 mg BPN has shown mild analgesic effect without any side effects.