ED50 of sevoflurane for I-Gel removal in anesthetized children in cataract surgeries using subtenon block

OBJECTIVE: The aim of this study was to determine the minimum concentration of sevoflurane required for I-Gel removal in 50% children undergoing elective cataract surgery. DESIGN: A prospective observational study. SETTING: A single tertiary care surgical center. MATERIALS AND METHODS: Our study enrolled 20 American Society of Anesthesiologists I and II children aged 2-10 years, undergoing elective cataract surgery. Anesthesia was induced with sevoflurane and oxygen/nitrous oxide mixture and a size 2 I-Gel was inserted. A subtenon block was administered in all children before surgical incision. Sevoflurane was used for maintenance of anesthesia. Predetermined end-tidal concentration of sevoflurane was maintained for 10 min at the end of surgery before I-Gel removal was attempted. End-tidal concentrations were increased/decreased using the Dixon up-down method (with 0.2% as a step size) in the next patient depending on the previous patient's response. Patient responses to I-Gel removal were classified as “movement” or no “movement”. RESULTS: Minimum concentration of sevoflurane required for successful removal of a I-Gel in 50% (ED50) and 95% (ED95) of children was 0.44% (95% confidence interval [CI], 0.34-0.52%) and 0.77% (95% CI, 0.63-1.2%), respectively. CONCLUSION: A very low end-tidal concentration of sevoflurane (ED50 of 0.44% ED95 of 0.77%) is required for I-Gel removal in children in cataract surgery with the supplementation of subtenon block.