Neuromuscular blocking effects of rocuronium during desflurane, isoflurane, and sevoflurane anaesthesia

PURPOSE: To determine the magnitude of the potentiation of rocuronium by desflurane, isoflurane and sevoflurane 1.5 MAC anaesthesia.

METHODS: In a prospective, randomised, study in 80 patients, the cumulative dose-effect curves for rocuronium were determined during anaesthesia with desflurane, sevoflurane and isoflurane (with N2O 70%, 15 min steady state) or total intravenous anaesthesia (TIVA) using propofol/fentanyl. Neuromuscular block was assessed by acceleromyography (TOF-Guard) after train-of-four (TOF) stimulation of the ulnar nerve (2 Hz every 12 sec, 200 microseconds duration). Rocuronium was administered in increments of 100 micrograms.kg-1 until first twitch (T1) depression > 95%.

RESULTS: Rocuronium led to more pronounced T1 depression with desflurane or sevoflurane anaesthesia than with TIVA. The ED50 and ED95 were lower during desflurane (95 +/- 25 and 190 +/- 80 micrograms.kg-1) and sevoflurane (120 +/- 30 and 210 +/- 40 micrograms.kg-1) than with TIVA (150 +/- 40 and 310 +/- 90 micrograms.kg-1) (P < .01), while the difference was not significant for isoflurane (130 +/- 40 and 250 +/- 90 micrograms.kg-1). Following equi-effective dosing (T1 > 95%) the duration to 25% T1 recovery, recovery index (25/75), and TOF0.70 was: 13.2 +/- 1.8, 12.7 +/- 3.4, and 26.9 +/- 5.7 min during anaesthesia with desflurane; 15.5 +/- 5.0, 11.4 +/- 3.8, and 31.0 +/- 6.0 min with sevoflurane; 13.9 +/- 4.7, 10.7 +/- 3.3, and 26.3 +/- 8.9 min with isoflurane; and 13.9 +/- 3.9, 11.3 +/- 5.7, and 27.5 +/- 8.2 min with TIVA anaesthesia (P: NS).

CONCLUSION: Interaction of rocuronium and volatile anaesthetics resulted in augmentation of the intensity of neuromuscular block but did not result in significant effects on duration of or recovery from the block.