Canadian Journal of Anesthesia, Vol 12, 608-621, Copyright © 1965 by Canadian Anesthesiologists' Society

The Respiratory, Circulatory, and Analgesic Effects of Naloxone-Narcotic Mixtures in Anaesthetized Subjects

¹ Department of Anesthesia, Mercy Hospital, Pittsburgh, Pa. Dr. Foldes is in the Division of Anesthesiology, Montefiore Hospital and Medical Center, 111 E. 210th St., Bronx, New York 10467

Sixty subjects premedicated with 100 mg. pentobarbital and 0.3 to 0.4 mg. scopolamine were lightly anaesthetized with thiopental and nitrous oxide-oxygen, and were divided into six groups of ten persons each. The subjects of each group received intravenously 0.02 mg./kg, oxymorphone, 0.2 mg./kg. morphine, or 2 mg./kg. meperidine, alone or together with 5 µg./kg. naloxone. Pulse rate, blood pressure, respiratory rate, and tidal and minute volume were determined after induction of anaesthesia, three, six, and ten minutes after the administration of the narcotics or the narcotic-naloxone combinations, and at the termination of surgery. When administered alone, the three narcotics caused significant respiratory depression, which was greatest with meperidine and least with morphine. The narcotic-induced bradycardia and hypotension were less marked. The simultaneous administration of naloxone markedly antagonized, but did not completely prevent, the respiratory depression caused by the narcotics. The antagonistic effect of naloxone on the circulatory depression was less marked. The admixture of nalaxone did not seem to antagonize the analgesic potency of the narcotics as measured by their ability to supplement thiopental-nitrousoxide-oxygen anaesthesia. Neither did the admixture of the narcotic antagonist have any effect on the state of consciousness observed five minutes after the termination of anaesthesia.