Respiratory function following nalbuphine and morphine in anaesthetized man

Abstract

In 4 patients anaesthetized with thiopentone, 66% nitrous oxide and 1% halothane, the effects of a single i.v. dose of nalbuphine 4.5, 8, 15, 25 or 50 mg/170 kg or morphine 3, 5, 10 or 17.5 mg/70kg on total ventilation and end-tidal carbon dioxide concentration have been measured. Depression of respiration occurred with both drugs and with all doses. The lower doses of nalbuphine produced more depression than equianalgesic doses of morphine. Conventional equianalgesic doses produced similar degrees of depression. With the highest dose of morphine, respiratory impairment progressed to apnoea whereas, with nalbuphine, apnoea did not occur in any patient. With increasing dosage of nalbuphine there appeared to be a limit to the extent of respiratory depression. The highest dose of nalbuphine produced less depression than some lower doses, suggesting a reversal effect. © 1986 British Journal of Anaesthesia.