Relationship Between Entropy-Guided Sevoflurane Administration and End Oxygenator Sevoflurane Concentration in Adult Patients Undergoing Cardiopulmonary Bypass Surgery
Abstract
Background:
Cardiopulmonary bypass (CPB) during cardiac surgery poses physiological challenges such as altered drug pharmacokinetics. Sevoflurane, a commonly used volatile agent, provides favorable myocardial protection; however, precise dosing during CPB remains difficult. Entropy monitoring, which assesses cerebral and electromyographic activity, offers real-time guidance on anesthetic depth. This study aimed to investigate entropy-guided sevoflurane administration relation with end-oxygenator sevoflurane concentrations, in patients undergoing elective on-pump cardiac surgery.
Materials and Methods:
A prospective, randomized controlled trial was conducted in a single tertiary care center affiliated with a teaching hospital, enrolling 74 adult patients scheduled for elective on-pump cardiac surgeries. Participants were randomized into two groups: fixed sevoflurane concentration (1.5% v/v) and entropy-guided sevoflurane titration. Depth of anesthesia was monitored with state entropy (SE) and response entropy (RE), end-oxygenator sevoflurane concentrations, and clinical parameters.
Results:
Compared to the fixed-dose group, the entropy-guided group exhibited lower SE and RE values intraoperatively, indicating tighter control of anesthetic depth. Higher sevoflurane dial settings were used initially in the entropy group, resulting in higher end-oxygenator concentrations. Although mean arterial pressure and arterial blood gas parameters remained within acceptable ranges in both groups, VIS was higher in the entropy-guided group, suggesting an increased requirement for vasoactive and inotropic support. There was no statistically significant variation in postoperative mechanical ventilation duration or intensive care unit stay between the two groups.
Conclusion:
Overall, entropy monitoring facilitated a precise titration of sevoflurane without adversely affecting immediate postoperative outcomes.