title: Recovery of train-of-four after mivacurium.
abstract: The present study was designed to determine the time-course of recovery of the train-of-four (TOF) ratio during spontaneous recovery from mivacurium-induced block. Fifteen patients, free of neuromuscular disease, undergoing general endotracheal anaesthesia with isoflurane were studied. After anaesthetic induction, patients received a bolus dose of mivacurium 0.15 mg.kg-1. The TOF was then recorded continuously every 12 sec with a mechanogram (adductor pollicis monitor). When the TOF ratio recovered spontaneously to 0.9, an additional 0.05 mg.kg-1 of mivacurium was given. The durations required for recovery from a TOF ratio of 0.3 to 0.7 (DUR0.3-0.7) and from a TOF ratio of 0.3 to 0.9 (DUR0.3-0.9) were determined. The DUR0.3-0.7 averaged 7.0 +/- 2.5 min (range 3.4-12.2 min). The DUR0.3-0.9 averaged 11.8 +/- 3.9 min (range 6.0-20.2 min). There was no evidence of prolongation of recovery times (cumulation) following repeated dosing. The present data indicate that, in patients with normal cholinesterase activity (clinical duration 7-25 min), waiting 20 min beyond the time when fade is no longer apparent by visual or tactile evaluation is sufficient to attain a TOF ratio greater than 0.7-0.9 during spontaneous recovery from mivacurium, and may enable anaesthetists to avoid antagonism of mivacurium-induced block.
authors.affiliation: Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06510.
authors.forename: S J
authors.initials: SJ
authors.lastname: Brull
authors.forename: N R
authors.initials: NR
authors.lastname: Connelly
authors.forename: D G
authors.initials: DG
authors.lastname: Silverman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000762:Anesthesia Recovery Period; D000770:Anesthesia, Endotracheal; D002802:Cholinesterases / Q000378:metabolism; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D007530:Isoflurane / Q000008:administration & dosage; D007546:Isoquinolines / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D000077590:Mivacurium; D009119:Muscle Contraction / Q000187:drug effects*; D009469:Neuromuscular Junction / Q000187:drug effects*; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage*; D012449:Safety; D013933:Thumb; D014459:Ulnar Nerve / Q000502:physiology
chemical_list: D007546:Isoquinolines; D003473:Neuromuscular Nondepolarizing Agents; D000077590:Mivacurium; D007530:Isoflurane; D002802:Cholinesterases