Objective: Postoperative shivering is common and has potentially adverse side effects in high-risk patients. Meperidine, which binds to both mu- and kappa-opioid receptors, is reported to be more effective in treating shivering than morphine or fentanyl. Recent data indicate that much of meperidine's special antishivering effect may be mediated by its kappa-opioid receptor activity. Nalbuphine, an opioid agonist/antagonist also has a potent affinity for kappa-receptors. The aim of this study was to evaluate the antishivering effect of nalbuphine in comparison to meperidine.
Methods: 100 ASA physical status I-II patients shivering after elective surgery were included in the study. General anaesthesia was performed with thiopentone, low-dose fentanyl and enflurane in N2O/O2. After arrival in the recovery room patients shivering within 5 min received either meperidine 25 mg or nalbupine 10 mg in a double-blind, randomised manner. The duration and severity of shivering, heart rate, respiratory rate, blood pressure, end-tidal CO2 concentration, O2-saturation and awareness were documented until 20 min after injection. Patients in need of a second injection were excluded from the study.
Results: Demographic variables, duration of operation and temperature decreases were not significantly different between treatment groups. The suppression of shivering was achieved within 4.0 +/- 3.5 or 4.6 +/- 4.1 min following the injection of meperidine or nalbuphine, respectively (p = NS). Vital signs and postoperative vigilance showed no significant differences. No adverse side effects were observed.
Discussion: The data indicated that nalbuphine suppressed postoperative shivering as effectively and timely as meperidine in equianalgesic doses. The observation is consistent with the hypothesis that stimulation of kappa-opioid receptors is a likely explanation for much of meperidine's antishivering action.