Cp50 of propofol with and without nitrous oxide 67%.
The target concentration of propofol required to prevent response to surgical incision was determined in 60 unpremedicated ASA I or II patients, who breathed either oxygen-enriched air or nitrous oxide 67% in oxygen. Propofol was infused using a target-controlled infusion system incorporating the standard 'Diprifusor' pharmacokinetic model, with the target concentration for each patient decided by up/down sequential allocation. Presence or absence of movement in response to a groin incision was determined by the surgeon. The calculated blood concentration at which 50% of patients responded (Cp50calc), determined by probit analysis, was 6.8 micrograms ml-1 for patients who breathed oxygen-enriched air and 4.9 micrograms ml-1 for those who breathed nitrous oxide 67% in oxygen.
Stuart
P C
PC
Department of Anaesthesia, University of Glasgow, UK.
Stott
S M
SM
Millar
A
A
Kenny
G N
GN
Russell
D
D
D000293:Adolescent; D000328:Adult; D000368:Aged; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D018686:Anesthetics, Intravenous / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems; D004357:Drug Synergism; D005260:Female; D006552:Hernia, Inguinal / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000187:drug effects*; D009609:Nitrous Oxide / Q000008:administration & dosage*; D015742:Propofol / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics
D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D009609:Nitrous Oxide; D015742:Propofol