SPECTRAL ENTROPY FOR ASSESSING THE PATIENT RESPONSIVENESS DURING PROPOFOL/FENTANYL SEDATION IN DAY CARE SURGERIES

Abstract

Background: For day care surgery under monitored anesthetic care, precise monitoring of sedation depth facilitates optimization of dosage and prevents adverse complications from over sedation. Conventionally subjective sedation scales, such as the Modified observer’s assessment of alertness/ sedation scale (MOAA/S) have been widely utilized for sedation monitoring. The newer monitoring called entropy is considered to be beneficial for objective assessment with combined use of opioids and hypnotics if applied. The primary objective is to determine measurement of entropy as a marker for measuring depth of anaesthesia.

Methods: Two groups P and PF ( with 25 patients each) received either propofol 1mg/kg followed by maintenance infusion of 250 mic/ kg/hr whereas “PF”group received additional single dose of fentanyl 2 mic/kg respectively. The values of response entropy (RE) and state entropy (SE) corresponding to each MOAA/S (5 to 0) were determined.

Results: The patient’s demographic profile and clinical characteristics were comparable in both the groups. No difference observed in duration of anaesthesia and surgery in both groups. No difference observed in MOAA/S in both groups.  The results shows a highly significant differences in the observed means of SE, RE, MAP and HR with considerably higher mean values in group P (p<0.0001). However other parameter such as SPO2, ETCO2 and RR were almost comparable in both groups.

Conclusion: The mean value of SE and RE in group P and PF indicates that deeper plane of anaesthesia is observed in PF group. It is concluded that in assessing the level of hypnosis during intra-operative sedation in MAC, entropy corresponds to MOAA/S and increases or decreases proportionately depending upon increase or decrease level of sedation. Hence from these results it is proposed that entropy monitoring is a reliable monitoring index of anaesthesia depth in MAC.

Keywords: Entropy, Propofol, Sedation, Day care surgery, Observer’s assessment of alertness/ sedation scale, Monitored anaesthesia Care