The uptake of isoflurane during anaesthesia

Abstract

The uptake of isoflurane at a constant end‐expired concentration of 1.5% in oxygen was studied in 15 women, ASA 1 or 2, undergoing elective total abdominal hysterectomy. The anaesthetic was administered by a simple computer‐controlled to‐and‐fro closed system. After an initial period of wash‐in to the system, the rate of uptake of isoflurane decreased bi‐exponentially with a rapid reduction during the first 15 min. Perturbations from this bi‐exponential decline reflect changes in cardiac output. The mean (SD) cumulative use of isoflurane was 4.5 (0.43) ml after 30 min and 7.3 (0.79) ml after 60 min. Copyright © 1993, Wiley Blackwell. All rights reserved