The effects of nitrous oxide on the auditory evoked potential index during sevoflurane anaesthesia.
We have studied the effects of nitrous oxide on the auditory evoked response index (AAI-index) derived from the A-line monitoring device during sevoflurane anaesthesia in 21 patients undergoing minor ambulatory surgery. During sevoflurane anaesthesia with an AAI-index < 30, the addition or withdrawal of nitrous oxide in a concentration of 66% end tidal did not show any linear dose dependent change in AAI-index . However, comparing nitrous oxide > 40% to nitrous oxide < 10% end tidal concentration the AAI-index did decrease, p < 0.05. The AAI-index is either non-linear at deeper anaesthetic levels or is insensitive to the anaesthetic effects of nitrous oxide in terms of MAC-multiples.
Department of Cardiothoracic Anaesthetics and Intensive Care, Karolinska Hospital, Stockholm, Sweden.
G
G
Barr
R
R
Anderson
J
J
Jakobsson
D000328:Adult; D000556:Ambulatory Surgical Procedures; D019162:Anesthetics, Combined / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008738:Methyl Ethers / Q000494:pharmacology*; D008875:Middle Aged; D009609:Nitrous Oxide / Q000494:pharmacology*; D000077149:Sevoflurane
D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D009609:Nitrous Oxide