Reversal of epidural morphine-induced respiratory depression and pruritus with nalbuphine

The effect of nalbuphine on the respiratory depression, pruritus and analgesia induced by epidural morphine was determined in a randomized, prospective, double-blind, placebo-controlled fashion. Twenty ASA physical status I women received 0.1 mg·kg-1 epidural morphine at induction of general anaesthesia for elective total abdominal hysterectomy. Group 1 (n = 14) received 0.3 mg·kg-1 nalbuphine intravenously six hours after the epidural morphine administration. Group 2 (n = 6) received saline. Prior to agent administration, six patients from the nalbuphine group and four patients from the saline group had respiratory depression indicated by a PaCO2 greater than 45 mmHg. After nalbuphine administration the PaCO2 (mean ± SE) decreased from 49.5 ± 1.2 mmHg to 42.5 ± 0.7 mmHg (p < 0.005) while there was no significant change after saline administration. Nine of the 14 patients receiving nalbuphine appeared to become more sedated, despite an improvement in ventilation. Pruritus was antagonized by 0.1 mg·kg-1 nalbuphine (p < 0.006). There was no reversal of analgesia after administration of 0.3 mg·kg-1 nalbuphine.