Optimal End-Tidal Sevoflurane Concentration For Tracheal Extubation Of Deeply Anesthetized Adults

Aim: In general anesthesia the tracheal extubation is usually performed when the patiens are awaken completely and the airway protective reflection return.Great alteration of patients' respira- tion and circulation system can come out due to actions like pain,the stimulation of the trachea,sputum suction and extubation, which shows in patients as tachycardia, hypertension, cough and dysphoria and leads to high intracranial, abdominal, and intraocular pressure. This is extremely dangerous for those patients who are old and especially with cardiac and cerebral diseases. It has been a focus for anesthetists that how to control and minimize the peri-extubation reaction. We sought to determine the optimal end-tidal concentrations of sevoflurane required for the smooth tracheal extubation in 50% and 95% anesthetized adults.Method: We studied 40 adults, aged22–64 years old with an ASA physical status I or II, who were undergoing celioscope surgery. General anesthesia was induced with midazolam 0.05mg/kg, vecurinium 0.1mg/kg,propofol 1-1.5mg/kg, sufentanil 0.5μg/kg. Anesthesia was maintained with sevoflurane and oxygen. After the surgery, the target concentration was maintained for at least 10min.When the criterion of tracheal extubation was reached,the tracheal was extubated. Each target concentration at the time of removal was predetermined by the Dixon up-down method (with 0.1% as a step size) starting at 1.4% end-tidal concentration of sevoflurane. The tracheal extubation was considered successful when there was no coughing, clenching of teeth, or gross purposeful movements during or within 1min after removal and also if there was no breath holding,laryngospasm, or desaturation after removal.Results: The end-tidal concentration of sevoflurane to achieve successful tracheal extubation in 50% of adults was 0.87±0.11% and in 95% of adults was 1.13%±0.12% (95% confidence limits, 1.01～1.72%).Conclusion: we have determined that smooth tracheal extubation in 50% and 95% of anesthetized adults can be safely accomplished without coughing,moving, or any other airway complications at 0.87 and 1.13% end-tidal concentrations of sevoflurane.