Dose requirements of propofol by infusion during nitrous oxide anaesthesia in man. II: Patients premedicated with lorazepam.
The infusion rate of propofol required to supplement 67% nitrous oxide in oxygen to maintain surgical anaesthesia was determined in 72 patients premedicated with lorazepam. Following an induction dose of propofol 2 mg kg-1, groups of eight patients received an infusion of propofol varying from 60 to 200 micrograms kg-1 min-1. Probit analysis was used to determine the ED50 (130 micrograms kg-1 min-1; 95% confidence limits: 106-167 micrograms kg-1 min-1) and ED95 (348 micrograms kg-1 min-1; 95% confidence limits: 233-1296 micrograms kg-1 min-1) for propofol infusion. Whole blood propofol concentrations at the time of surgical incision correlated strongly with the infusion rate, giving an EC50 value of 2.5 micrograms ml-1, and an EC95 value of 5.92 micrograms ml-1. There was no significant correlation between the rate of infusion of propofol, or the total propofol dose, and the times to response to command, or to recall of birthdate.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D000777:Anesthetics / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008140:Lorazepam; D008297:Male; D008875:Middle Aged; D009609:Nitrous Oxide; D010636:Phenols / Q000008:administration & dosage* / Q000097:blood; D011229:Preanesthetic Medication; D015742:Propofol
D000777:Anesthetics; D010636:Phenols; D009609:Nitrous Oxide; D008140:Lorazepam; D015742:Propofol