[The analgesic effect of subarachnoid administration of tetracaine combined with low dose morphine or nalbuphine for spinal anesthesia].

The analgesic effect of subarachnoid administration of tetracaine combined with low dose morphine or nalbuphine for spinal anesthesia was evaluated in 60 ASA physical status class I or II patients. Dextrose solution (10%) was added to 0.4 mg morphine or 0.4 mg nalbuphine to make a total volume of 2 ml, which was injected intrathecally with tetracaine in a double-blind, randomized fashion. Vital signs, sensory level, motor block, pain score, and side effects were recorded every 2 min for the first 15 min and then at 15, 30, 45, and 60 min and at 30-min intervals until the patient complained of pain. Side effects and opioid requirements were recorded for the first 24 h. Complete analgesia (time from injection to first report of pain) lasted 180 +/- 51.6 min in the control group and increased to 238 +/- 71 min in group with addition of 0.4 mg nalbuphine, 250 +/- 74 min in group with addition of 0.4 mg morphine (p less than 0.05). The effective analgesia (time from injection to first opioid requirement) also increased in groups of nalbuphine and morphine than the control group. No differences in complete or effective analgesia was found between groups in the presence of nalbuphine or morphine. Results indicate that the addition of 0.4 mg nalbuphine or morphine to hyperbaric tetracaine for spinal anesthesia improves the quality of intraoperative analgesia and can last into the postoperative period. Side effects were less in nalbuphine group than with morphine group.