Isoflurane Vecuronium

Heier T., Caldwell J. E., Sessler D. I., and Miller, R. D. (1991) Mild intraoperative hypothermia increases duration of action and recovery time of vecuronium blockade during nitrous oxide-isoflurane anesthesia in humans. Anesthesiology 74, 815-819. 

In 113 patients undergoing general anesthesia, intravenous midazolam 15 mg slowed recovery of the twitch height after vecuronium and atracurium compared with diazepam. The recovery index was not altered (162). However, in another study in 20 patients, midazolam 0.3 mg/kg did not affect the duration of blockade, recovery time, intensity of fasciculations, or adequacy of relaxation for tracheal intubation produced by suxamethonium 1 mg/kg, nor the duration of blockade and adequacy of relaxation for tracheal intubation produced by pancuronium 0.025 mg/kg in incremental doses until 99% depression of muscle-twitch tension was obtained (161). Furthermore, in 60 patients undergoing maintenance anesthesia randomly assigned to one of six regimens (etomidate, fentanyl, midazolam, propofol, thiopental plus nitrous oxide, or isoflurane plus nitrous oxide), midazolam did not alter rocuronium dosage requirements (165). 

A 65-year-old man undergoing elective sternal debridement and rewiring was given a prophylactic infusion of vancomycin 1 g preoperatively. Anesthesia was induced with thiopental, suxamethonium, and fentanyl, and maintained with fentanyl, vecuronium, and isoflurane. A few minutes after wound irrigation with bacitracin (about 25U/ml), his blood pressure fell precipitously, necessitating intravenous fluids and adrenaline. His face and arms were flushed. Afterwards, he reported having had a rash several years before after the use of an over-the-counter ointment composed of polymyxin B, bacitracin, and neomycin. 

Symptoms suggestive of severe sensorimotor neuropathy developed in a 40-year-old woman 15 days after admission for a severe exacerbation of asthma (7). During this time she was given isoflurane 0.5-3% in oxygen, vecuronium bromide 4-6 mg/hour, and fentanyl 100 micrograms/hour. The neuropathy resolved spontaneously over the next 3 months. 

Rupp SM, Miller RD, Gencarelli PJ. Vecuronium-induced neuromuscular blockade during enflurane, isoflurane, and halothane anesthesia in humans. Anesthesiology 1984 60(2) 102-5. 

One study in children found that the potentiation of vecuronium was greater with isoflurane than with enflurane, and halothane had a lesser... 

The dosage of the neuromuscular blocker may need to be adjusted according to the anaesthetic in use. For example, the dosage of atracurium can be reduced by 25 to 30% if, instead of balanced anaesthesia (with thiopental, fentanyl and nitrous oxide/oxygen)," enflurane is used, and by up to 50% if isoflurane or desflurane are used. Another study recommended reduced doses of neuromuscular blockers such as atracurium and tubocurarine in children undergoing anaesthesia with enflurane or isoflurane. In one study, enflurane and isoflurane reduced the vecuronium infusion rate requirements by as much as 70%, when compared with fentanyl anaesthesia. Another study demonstrated that although halothane and isoflurane could both increase the neuromuscular potency of vecuronium, only isoflurane prolonged the recovery from neuromuscular blockade. ... 

Vanlimhout LEH, Booij LHDJ, van Egmond J, Robertson EN Effect of isoflurane and sevoflurane on the magnitude and time courae of neuromuscular block produced by vecuronium, pancuronium and atracurium. BrJAnaesth (1996) 76, 389-95. 

In a study of 16 surgical patients, 8 took oral clonidine 4 to 5.5 micrograms/kg 90 minutes before their operation. Anaesthesia was induced by thiamylal, and maintained with nitrous oxide/isoflurane/oxygen supplemented by fentanyl. Clonidine increased the duration of neuromuscular blockade following the use of vecuronium by 26.4%, when compared with the patients not taking clonidine. ... 

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