Effects of sevoflurane, propofol or alfaxalone on neuromuscular blockade produced by a single intravenous bolus of rocuronium in dogs

To compare the effects of sevoflurane, propofol and alfaxalone on the neuromuscular blockade induced by a single intravenous bolus of rocuronium in dogs. A randomized, prospective, crossover experimental study. A total of eight adult Beagle dogs (four female, four male), weighing 8.9–15.3 kg and aged 5–7 years. The dogs were anesthetized three times with 1.25× minimum alveolar concentration of sevoflurane (SEVO treatment) and 1.25× minimum infusion rate of propofol (PROP treatment) or alfaxalone (ALFX treatment) at intervals of ≥14 days. Neuromuscular function was monitored with train-of-four (TOF) stimulation of the peroneal nerve by acceleromyography. After recording the control TOF ratio (TOFRC), a single bolus dose of rocuronium (1 mg kg–1) was administered intravenously. The times from rocuronium administration to achieving TOF count 0 (onset time), from achieving TOF count 0 to the reappearance of TOF count 4 (clinical blockade period), from 25% to 75% of TOFRC (recovery index) and from achieving TOF count 0 to TOF ratio/TOFRC >0.9 (total neuromuscular blockade duration) were recorded. The onset time and recovery index did not differ among the treatments. The median clinical blockade period was longer in the SEVO treatment [27.3 (26.0–30.3) minutes] than in PROP [16.6 (15.4–18.0) minutes; p = 0.002] and ALFX [22.4 (18.6–23.1) minutes; p = 0.017] treatments; and longer in the ALFX treatment than in the PROP treatment (p = 0.020). The mean total neuromuscular blockade duration was longer in the SEVO treatment (43.7 ± 9.9 minutes) than in PROP (25.1 ± 2.7 minutes; p < 0.001) and ALFX (32.5 ± 8.4 minutes; p = 0.036) treatments. Compared with alfaxalone and propofol, sevoflurane prolonged rocuronium-induced neuromuscular blockade by a significantly greater extent in dogs.