[Nalbuphine following fentanyl. Postoperative analgesia]

It has been suggested in various studies that the opiate agonist/antagonist nalbuphine (Nubain) provides for effective reversal of the respiratory depression after fentanyl while maintaining postoperative analgesia. We tested this hypothesis in a relatively large number of patients. The study consisted of two parts: one randomized open, the other randomized double-blind, each with 150 ASA I or II patients aged 18 to 65 years. After premedication with atropine 0.5 mg and flunitrazepam 0.5 mg, anaesthesia was induced with flunitrazepam 0.5 mg, fentanyl 0.1 mg, and etomidate 10 mg and maintained with N2O/O2, 2/1, and additional increments of 0.1 mg fentanyl as required. Relaxation for intubation and surgery was obtained with vecuronium, atracurium, or pancuronium depending on the expected duration of anesthesia. After the operation the patients were extubated and the residual effects of fentanyl antagonized with naloxone 0.05 mg or nalbuphine 10 mg or 20 mg i.v. (randomized open or double-blind). The patient data and fentanyl dosages are given in Table 1. Postoperative pain was assessed by the time interval between administration of the opiate antagonist and the requirement for the first analgesic medication. Figures 1a and b and Table 2 indicate that after nalbuphine 20 mg the first analgesic was required significantly later than after naloxone 0.05 mg (median 115 or 123 min after nalbuphine 20 mg vs 56 or 52 min after naloxone 0.05 mg; P less than 0.02). There was no significant difference between nalbuphine 10 mg and naloxone 0.05 mg. The open and double-blind studies gave virtually identical results. Sixty minutes after administration of 20 mg nalbuphine, vigilance was significantly reduced.(ABSTRACT TRUNCATED AT 250 WORDS)