Sevoflurane and isoflurane impair edrophonium reversal of vecuronium-induced neuromuscular block.
OBJECTIVE
A dose-response relationship study for edrophonium to examine the modification of volatile anaesthetics on reversal of vecuronium block.


METHODS
One hundred and twenty ASA (I-II) patients were anaesthetized with sevoflurane, isoflurane (1 minimum alveolar anaesthetic concentration [MAC] end-tidal concentration), or fentanyl-diazepam anaesthesia, in combination with 66% nitrous oxide (n = 40 for each group). The evoked electromyogram (EMG) response of the abductor digiti minimi was monitored at 20 sec intervals following train-of-four (TOF) stimulation of the ulnar nerve. The initial neuromuscular block was produced by vecuronium 100 micrograms.kg-1. When the amplitude of the first response (T1) had spontaneously recovered to 10% of the control, edrophonium (0, 125, 400, 700 or 1000 micrograms.kg-1; eight patients each) was randomly administered, and the ratio of the fourth TOF to the first response (TOFR) was monitored at one minute intervals for 10 min.


RESULTS
Sevoflurane and isoflurane impaired the edrophonium-assisted TOFR recovery in an edrophonium dose and time dependent manner. The dose-response curves at 10 min exhibited a greater shift to the right in the sevoflurane and isoflurane groups than in the fentanyl-diazepam-nitrous oxide group (P < 0.05). Higher ED50 values (the edrophonium dose required to obtain TOFR value of 50%) in the sevoflurane (> 1000 micrograms.kg-1) and isoflurane groups (851 micrograms.kg-1) were observed than in the fentanyl-diazepam-nitrous oxide group (339 micrograms.kg-1) (P < 0.05).


CONCLUSIONS
One MAC sevoflurane and isoflurane anaesthesia impair edrophonium reversal of vecuronium block to a similar degree.
Morita
T
T
Department of Anesthesiology and Reanimatology, Gunma University School of Medicine and Hospital, Japan.
Kurosaki
D
D
Tsukagoshi
H
H
Sugaya
T
T
Saito
S
S
Sato
H
H
Fujita
T
T
D000328:Adult; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D002800:Cholinesterase Inhibitors / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004491:Edrophonium / Q000494:pharmacology*; D004987:Ethers / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007530:Isoflurane / Q000494:pharmacology*; D008738:Methyl Ethers; D008875:Middle Aged; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000502:physiology; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology*; D000077149:Sevoflurane; D014673:Vecuronium Bromide / Q000494:pharmacology*
D018685:Anesthetics, Inhalation; D002800:Cholinesterase Inhibitors; D004987:Ethers; D008738:Methyl Ethers; D003473:Neuromuscular Nondepolarizing Agents; D000077149:Sevoflurane; D004491:Edrophonium; D014673:Vecuronium Bromide; D007530:Isoflurane