British Journal of Anaesthesia, 1995, Vol. 74, No. 4 362-367
© 1995 The Board of Management and Trustees of the British Journal of Anaesthesia
research-article |
Propofol administered by a manual infusion regimen
Nuffield Department of Anaesthetics, University of Oxford, John Radcliffe Hospital Headington, Oxford
Medical Affairs Department, Zeneca Pharmaceuticals Macclesfield, Cheshire
Correspondence to J. W. S.
We have evaluated the clinical utility and blood propofol concentrations produced with two dif ferent infusion regimens for propofol, given to supplement 67% nitrous oxide-morphine anaesthesia. Patients received a standardized three-step infusion of propofol based either on body weight (weight-corrected group) or on a mean body weight of 70 kg (standard dose group). Both groups showed similar cardiovascular stability and recovery times. In the 48 patients studied, isoflurane was used as a supplement in nine (two in the weight-corrected group). Apparent steady state blood propofol concentrations were 3.41 (SD 0.69) µg ml–1 in the weight-corrected group and 3.46 (0.79) µg ml–1 in the standard dose group. These results suggest that for patients weighing 60–90 kg body weight, a standard dose infusion regimen may be a suitable starting point. In routine clinical practice, the need for isoflurane supplementation may be avoided by subsequent titration of the infusion rate according to clinical response. Computer simulation of the actual infusion rates used in each patient has allowed retrospective comparison of the predictive performance of different pharmaco kinetic descriptors for propofol. The variables described by Tackley and colleagues provided a more accurate prediction of the measured blood propofol concentration than did the variable set reported by Gepts and colleagues.