The influence of changes in end-tidal carbon dioxide upon the Bispectral Index.
Carbon dioxide is known to affect consciousness in animals and humans. We surmised that changes in end-tidal carbon dioxide during anaesthesia might affect the Bispectral Index. Twenty-four patients due to undergo surgery were anaesthetised with fentanyl and a propofol infusion. The Bispectral Index, pulse rate and blood pressure were recorded while end-tidal carbon dioxide levels were changed. The patients acted as their own controls as they were subjected to high, normal and low levels of end-tidal carbon dioxide (3-12 kPa) according to a randomised sequence. There were no changes in the Bispectral Index or haemodynamic variables resulting from manipulation of the end-tidal carbon dioxide. At the level of hypnosis involved in this study, changes in end-tidal carbon dioxide, within the range tested, do not result in changes in the Bispectral Index.
Turnbull
D
D
Royal Hallamshire Hospital, Glossop Road, Sheffield, S10 5DA, UK.
Furlonger
A
A
Andrzejowski
J
J
D000328:Adult; D000771:Anesthesia, Intravenous / Q000379:methods; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000502:physiology*; D018592:Cross-Over Studies; D004569:Electroencephalography; D005260:Female; D006339:Heart Rate; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D016857:Hypocapnia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D011446:Prospective Studies
D002245:Carbon Dioxide