Abstract: Objective To evaluate the safety and effectiveness of the observing bellow method under minimal fresh gas flow anesthesia for assessing air leakage of the laryngeal mask airway. Methods Eight hundred and sixteen patients who underwent general anesthesia with a laryngeal mask airway were included in this study. Air leakage of laryngeal mask was assessed by using both the observing bellow method and the auscultation and palpation method. The time spent in executing these two methods and their assessment results were recorded. The rates of both missing or incorrect assessments were calculated. Results Air leakage of laryngeal mask occurred in 30 of 816 patients(3.68%). No missing and incorrect assessment was made with the observing bellow method. However, 2 incorrect, but no missing assessments were made with the auscultation and palpation method. The validity and accuracy of the assessment with two methods were comparable. However, observing bellow method took longer (5.3±0.9) s to identify leakage than the auscultation and palpation method (4.0±1.1) s did (P<0.01), but determined non-leakage of the laryngeal mask much faster (23.2±3.9) s than the auscultation and palpation method (47.2±6.9) s did (P<0.01). Conclusions The observing bellow method is safe, simple, and convenient for assessing air leakage of the laryngeal mask under minimal fresh gas flow anesthesia, especially combined with the auscultation and palpation method.
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