Effect of entropy-guided low-flow desflurane anaesthesia on laryngeal mask airway removal time in children undergoing elective ophthalmic surgery - A prospective, randomised, comparative study

Background and Aims: In children, entropy-guided titration of isoflurane and sevoflurane leads to faster recovery after anaesthesia. However, role of entropy in recovery following desflurane anaesthesia is not known. Hence, we compared laryngeal mask airway (LMA) removal time and desflurane consumption with entropy and minimal alveolar concentration-guided titration in children given low-flow desflurane anaesthesia. Methods: After ethics committee approval and parental consent, 80 American Society of Anesthesiologists grade I-II children, age 2-14 years, undergoing elective ophthalmic surgery were randomised into entropy and minimal alveolar concentration-guided groups. After LMA insertion, anaesthesia was maintained using oxygen, air (FiO 2 0.5) and desflurane using low fresh gas flow of 0.75 L/min. In the entropy-guided group, desflurane was titrated to maintain state entropy between 40 and 60. In the minimal alveolar concentration-guided group, desflurane was titrated to maintain a minimal alveolar concentration between 1 and 1.3. We recorded LMA removal time (from switching off desflurane at the end of surgery till removal of LMA), haemodynamic parameters, uptake and consumption of desflurane between the groups. Results: LMA removal time was significantly decreased in the entropy-guided group in comparison to the minimal alveolar concentration-guided group (4.34 +/- 2.03 vs 8.8 +/- 2.33 min) (P < 0.0001). Consumption of desflurane was significantly less in the entropy-guided group compared with the minimal alveolar concentration-guided group (18.7 +/- 5.07 vs 25.3 +/- 8.11 mL) (P < 0.0001). Conclusion: Entropy-guided low-flow desflurane anaesthesia is associated with faster LMA removal and reduced consumption of desflurane in children undergoing ophthalmic surgery.