DUPLICATE PUBLICATION: Comparison of entropy and bispectral index values during propofol induction

OBJECTIVE: To identify the entropy levels that would correspond to bispectral index (BIS) levels in general anesthesia (GA) induction in patients who will undergo elective lumbar disc surgery (LDS).

METHODS: Thirty cases who underwent LDS under GA were included in our study after obtaining patient consent and approval of the Ethics Committee of Afyon Kocatepe University Medical School, Afyonkarahisar, Turkey, between January 01, 2004 to December 31, 2005. Bispectral index and entropy electrodes were applied at the same time to 30 cases in the study group. In order to assess the level of sedation during anesthesia and recovery, ‘Observer’s Assessment of Alertness/Sedation’ (OAA/S) scale was used. Bispectral index, state-entropy (SE), response-entropy (RE), and OAA/S values were recorded simultaneously.

RESULTS: Induction OAA/S scores were in correlation with BIS and entropy values (RE-SE) in 30 cases. A significant difference was found between BIS and entropy induction values (p=0.0398). Induction mean arterial pressure and heart rate values at 30, 60, 90, and 120 seconds were lower than the values of the control, which was statistically significant (p=0.0412).

CONCLUSION: During the induction of GA, we found entropy values to be more sensitive and they demonstrated a more rapid increase than BIS. Therefore, it would be safer to monitor entropy while using agents of induction that might cause severe hypotension. Induction agents that might cause severe hypotension could be more safely administered under entropy monitoring.