BACKGROUND AND OBJECTIVE: The end-tidal desflurane concentration required for smooth removal of the laryngeal mask airway (LMA) has not been established. Therefore, we aimed to find the end-tidal desflurane concentration for safe, smooth, and uncomplicated LMA removal. METHODS: The study was approved by the Ethical Committee of the Ministry of Health, Diskapi Yildirim Beyazit Research and the Training Hospital, Ankara, Turkey. All patients provided written consent. A total of 23 adults, 18-60 years of age and American Society of Anesthesiologists physical status class I, who had been scheduled for urological surgery were included in the study. The intravenous induction of anaesthesia was performed with propofol 2.5 mg kg⁻¹ and remifentanil 10 μg within 30 s. The LMA was inserted. Maintenance of anaesthesia was provided by desflurane, with nitrous oxide and oxygen. The LMA was removed at predetermined end-tidal desflurane concentrations at the end of surgery. The concentration at which LMA removal was attempted was determined by Dixon's up-down method with 0.5% as the step size. When LMA removal was accomplished without coughing, teeth clenching, gross purposeful movements, breath holding, laryngospasm, and desaturation to SpO(2) less than 90%, it was considered a smooth (successful) removal. RESULTS: For smooth removal of the LMA, end-tidal desflurane EC50 was 2.1% [95% confidence interval (CI) 1.1-2.9%], and the EC95 value was 3.9% (95% CI 3.1-7.9%). CONCLUSION: The EC95 of end-tidal desflurane for the smooth removal of the LMA is 3.9%. LMA removal in adults receiving desflurane may be possible at approximately 0.7 minimum alveolar concentration.
BACKGROUND AND OBJECTIVE: The end-tidal desflurane concentration required for smooth removal of the laryngeal mask airway (LMA) has not been established. Therefore, we aimed to find the end-tidal desflurane concentration for safe, smooth, and uncomplicated LMA removal. METHODS: The study was approved by the Ethical Committee of the Ministry of Health, Diskapi Yildirim Beyazit Research and the Training Hospital, Ankara, Turkey. All patients provided written consent. A total of 23 adults, 18-60 years of age and American Society of Anesthesiologists physical status class I, who had been scheduled for urological surgery were included in the study. The intravenous induction of anaesthesia was performed with propofol 2.5 mg kg⁻¹ and remifentanil 10 μg within 30 s. The LMA was inserted. Maintenance of anaesthesia was provided by desflurane, with nitrous oxide and oxygen. The LMA was removed at predetermined end-tidal desflurane concentrations at the end of surgery. The concentration at which LMA removal was attempted was determined by Dixon's up-down method with 0.5% as the step size. When LMA removal was accomplished without coughing, teeth clenching, gross purposeful movements, breath holding, laryngospasm, and desaturation to SpO(2) less than 90%, it was considered a smooth (successful) removal. RESULTS: For smooth removal of the LMA, end-tidal desflurane EC50 was 2.1% [95% confidence interval (CI) 1.1-2.9%], and the EC95 value was 3.9% (95% CI 3.1-7.9%). CONCLUSION: The EC95 of end-tidal desflurane for the smooth removal of the LMA is 3.9%. LMA removal in adults receiving desflurane may be possible at approximately 0.7 minimum alveolar concentration.