Evaluation of effect of entropy monitoring on isoflurane consumption and recovery from anesthesia.

Background and Aims: Entropy monitoring entails measurement of the effect of anesthetic on its target organ rather than merely the concentration of anesthetic in the brain (indicated by alveolar concentration based on which minimum alveolar concentration [MAC] is displayed). We proposed this prospective randomised study to evaluate the effect of entropy monitoring on isoflurane consumption and anesthesia recovery period.

Material and Methods: Sixty patients undergoing total abdominal hysterectomy under general anesthesia using an endotracheal tube were enrolled in either clinical practice (CP) or entropy (E) group. In group CP, isoflurane was titrated as per clinical parameters and MAC values, while in Group E, it was titrated to entropy values between 40 and 60. Data including demographics, vital parameters, alveolar isoflurane concentration, MAC values, entropy values, and recovery profile were recorded in both groups.

Results: Demographic data and duration of surgery were comparable. Time to eye opening on command and time to extubation (mean ± standard deviation) were significantly shorter, in Group E (6.6 ± 3.66 and 7.27 ± 4.059 min) as compared to Group CP (9.77 ± 5.88 and 11.63 ± 6.90 min), respectively. Mean isoflurane consumption (ml/h) was 10.81 ± 2.08 in Group E and 11.45 ± 2.24 in Group CP and was not significantly different between the groups. Time to readiness to recovery room discharge and postanesthesia recovery scores were also same in both groups.

Conclusion: Use of entropy monitoring does not change the amount of isoflurane consumed during maintenance of anesthesia or result in clinically significant faster recovery.