Propofol infusion for maintenance of anesthesia in morbidly obese patients receiving nitrous oxide. A clinical and pharmacokinetic study.
BACKGROUND
The pharmacokinetic and pharmacodynamic properties of propofol indicate that this may be an appropriate agent for induction and maintenance of anesthesia in obese patients. This study was designed to assess the rates of recovery and the pharmacokinetics of propofol infusions in morbidly obese patients.


METHODS
Anesthesia was induced and maintained using a stepwise infusion regimen of propofol in eight morbidly obese patients. The patients' lungs were ventilated with nitrous oxide:oxygen (66:34%). Pharmacokinetic parameters were calculated from iterative blood sampling during the propofol infusion and during 8 h after its completion.


RESULTS
Results were compared with those from a concurrent study of propofol pharmacokinetics in nonobese adults. The initial volume of distribution of propofol was not modified in obese patients. Total body clearance increase was correlated to body weight (R = 0.76, 25.4 +/- 6.5 ml.kg-1.min-1, mean +/- SD). Volume of distribution at steady state was also correlated to body weight (R = 0.61, 1.63 +/- 0.54 l.kg-1, mean +/- SD). Propofol concentration at the time of eye opening in response to verbal command was 0.94 +/- 0.26 mg.l-1.


CONCLUSIONS
Results from this study confirm the absence of propofol accumulation in morbidly obese patients when the current dosing scheme is used. Dosing schemes expressed in mg.kg-1 are the same as those in normal patients.
Servin
F
F
Département d'Anesthésie-Réanimation, CHU Bichat-Claude Bernard, Paris, France.
Farinotti
R
R
Haberer
J P
JP
Desmonts
J M
JM
D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D004357:Drug Synergism; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D009609:Nitrous Oxide; D009767:Obesity, Morbid / Q000378:metabolism*; D015742:Propofol / Q000008:administration & dosage / Q000493:pharmacokinetics*
D009609:Nitrous Oxide; D015742:Propofol