title: Suppressive effect of nitrous oxide on motor evoked potentials can be reversed by train stimulation in rabbits under ketamine/fentanyl anaesthesia, but not with additional propofol.
abstract: The effect of nitrous oxide on myogenic motor evoked potentials (MEPs) after multipulse stimulation is controversial. We investigated the effects of propofol in this paradigm. MEPs were elicited electrically by a single pulse and by trains of three and five pulses in rabbits anaesthetized with ketamine and fentanyl. Nitrous oxide 30-70% was given and MEPs were recorded. After washout of nitrous oxide, propofol was given as a bolus of 10 mg kg(-1) followed by 0.8 (n=9) or 1.6 mg kg(-1) min(-1) (n=8) as a continuous infusion. Nitrous oxide was then re-administered and MEPs were recorded. Without propofol, nitrous oxide significantly reduced the amplitude of MEPs dose-dependently, but this effect was reversed by multipulse stimulation. Administration of low-dose propofol enhanced nitrous oxide-induced suppression, and this effect was reversed by five-pulse stimulation. However, high-dose propofol produced a greater increase in suppression, such that even five-pulse stimulation did not overcome the suppression. The results suggest that the degree of reversal of nitrous oxide-induced MEP suppression produced by multipulse stimulation is affected by the administration of propofol.
authors.affiliation: Department of Anesthesiology, Nara Medical University, Kashihara, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Sakamoto
authors.forename: M
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: S
authors.initials: S
authors.lastname: Inoue
authors.forename: H
authors.initials: H
authors.lastname: Furuya
mesh_terms: D019162:Anesthetics, Combined; D000778:Anesthetics, Dissociative; D018685:Anesthetics, Inhalation / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004558:Electric Stimulation / Q000379:methods; D019054:Evoked Potentials, Motor / Q000187:drug effects*; D005283:Fentanyl; D007649:Ketamine; D008297:Male; D009609:Nitrous Oxide / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D015742:Propofol / Q000494:pharmacology*; D011817:Rabbits
chemical_list: D019162:Anesthetics, Combined; D000778:Anesthetics, Dissociative; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D007649:Ketamine; D009609:Nitrous Oxide; D005283:Fentanyl; D015742:Propofol