Speed of reversal of vecuronium neuromuscular block with different doses of neostigmine in anesthetized dogs.
OBJECTIVE
Neostigmine is routinely used to reverse non-depolarizing neuromuscular block. Given its indirect mechanism, a plateau may exist whereby increasing doses of neostigmine do not result in clinical benefit. This study was designed to measure the speed of reversal of vecuronium-induced neuromuscular block in isoflurane-anesthetized dogs after the administration of three doses of neostigmine as used in clinical practice.


METHODS
Prospective, crossover, randomized study.


METHODS
Seven adult, mixed-breed dogs with a mean ± standard deviation (SD) age of 2.0 ± 0.8 years and weight of 19.1 ± 9.1 kg.


METHODS
Dogs were anesthetized on three occasions with isoflurane and administered vecuronium (0.1 mg kg-1) intravenously (IV). The train-of-four (TOF) ratio was measured on the pelvic limb with acceleromyography. When the second twitch of the TOF had returned spontaneously, atropine (0.03 mg kg-1) and neostigmine (0.02, 0.04 or 0.07 mg kg-1) were administered IV. Time to reach a TOF ratio of ≥0.9 after neostigmine administration was recorded.


RESULTS
Increasing the dose of neostigmine from 0.02 mg kg-1to 0.04 mg kg-1and 0.07 mg kg-1resulted in significant reductions in mean ± SD reversal times (10.5 ± 2.3, 7.4 ± 1.1 and 5.4 ± 0.5 minutes, respectively) (p < 0.0001) and smaller coefficients of variation (22%, 15% and 10%, respectively).


CONCLUSIONS
Increasing the dose of neostigmine from 0.02 mg kg-1to 0.04 mg kg-1and 0.07 mg kg-1produced faster and less variable reversal of vecuronium-induced neuromuscular block in isoflurane-anesthetized dogs. No ceiling effect was observed at this dose range.
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA. Electronic address: martinflores@cornell.edu.
Manuel
M
Martin-Flores
Institute of Basic and Applied Science, Veterinary Medicine, National University of Villa María, Córdoba, Argentina.
Augusto M
AM
Lorenzutti
Institute of Basic and Applied Science, Veterinary Medicine, National University of Villa María, Córdoba, Argentina.
Nicolás J
NJ
Litterio
Institute of Basic and Applied Science, Veterinary Medicine, National University of Villa María, Córdoba, Argentina.
Victor L
VL
Rossetti
Institute of Basic and Applied Science, Veterinary Medicine, National University of Villa María, Córdoba, Argentina.
Maria P
MP
Zarazaga
Institute of Basic and Applied Science, Veterinary Medicine, National University of Villa María, Córdoba, Argentina.
César C
CC
Bonetto
Institute of Basic and Applied Science, Veterinary Medicine, National University of Villa María, Córdoba, Argentina.
Gabriela E
GE
Aguirre
D018685:Anesthetics, Inhalation; D000818:Animals; D018592:Cross-Over Studies; D004285:Dogs; D005260:Female; D007530:Isoflurane; D008297:Male; D009388:Neostigmine / Q000008:administration & dosage*; D019148:Neuromuscular Blockade / Q000662:veterinary*; D061886:Neuromuscular Monitoring / Q000662:veterinary; D011446:Prospective Studies; D014673:Vecuronium Bromide / Q000037:antagonists & inhibitors*
D018685:Anesthetics, Inhalation; D009388:Neostigmine; D014673:Vecuronium Bromide; D007530:Isoflurane
acceleromyography; cholinesterase inhibitor; neostigmine; neuromuscular; train-of-four; vecuronium