Maintaining optimal anesthetic depth during cardiopulmonary bypass (CPB) in pediatric patients is challenging due to altered physiology and unreliable conventional monitoring. Entropy, a processed electroencephalogram metric, offers a potential solution. This study aimed to evaluate the relationship between end oxygenator sevoflurane concentration and entropy values during pediatric CPB using fixed-dose versus entropy-guided sevoflurane administration.

A prospective, randomized study was conducted on 62 pediatric patients undergoing congenital heart surgery with CPB. Patients were allocated into two groups: Group A received fixed-dose sevoflurane (1% v/v), and Group B received sevoflurane titrated to maintain entropy values between 40 and 60. Parameters such as end oxygenator sevoflurane concentration, entropy (Response and State entropy, RE and SE), and sevoflurane consumption were recorded intraoperatively. Postoperative hemodynamic data, length of stay, and complication rates were assessed.

Entropy-guided patients showed significantly higher end oxygenator sevoflurane concentrations [1.64 (1.51–1.85)% versus 1.0%, p = .001] and sevoflurane consumption (1.26 ± 0.12 vs 0.645 ± 0.03 mL/min, p = .001). RE and SE values were significantly lower in the entropy group (p = .001), indicating better anesthetic depth control. A negative correlation was found between entropy and sevoflurane concentration (r = −0.6987, p = .02). Despite higher postoperative inotropic scores in the entropy group (p = .001), no significant differences were found in length of stay, mechanical ventilation duration, or morbidity and mortality rates between groups.

Entropy-guided sevoflurane administration during pediatric CPB provides improved anesthetic depth control at the cost of higher anesthetic and inotropic requirements. However, it does not adversely affect clinical outcomes, supporting its safety and potential utility in refining pediatric anesthesia practices.