Background: Methods of determining proper endotracheal tube (ETT) cuff pressure to prevent air leakage include the minimal occlusive volume (MOV) technique, which uses auscultation, and the spirometer technique, which directly measures inspiratory and expiratory breathing volumes. Spirometers may measure even small air leakage, therefore, the spirometer technique requires a higher cuff pressure than the MOV technique to completely seal the airway. This study aimed to evaluate the difference in cuff pressure between the two techniques used to seal the airway.Methods: Thirty-five female patients were intubated using an ETT with a cuff, and cuff inflation was performed with both techniques at a 10-min interval in random order—the MOV technique and then the spirometer technique or vice versa. The cuff pressure was measured at each period.Results: The cuff pressures were 16.7 ± 1.2 cm H2O and 18.7 ± 1.3 cm H2O for the MOV and spirometer techniques, respectively. The cuff pressure for the spirometer technique was 2 cm H2O higher than that for the MOV technique and this difference was statistically significant (95% confidence interval, 0.7–3.3; P = 0.003). Considering the upper end (3.3 cm H2O) of the 95% confidence interval and the size of one scale unit (2 cm H2O) of a manometer, the difference in cuff pressure was up to 4 cm H2O in practice.Conclusions: Even though the air leakage sound disappears on auscultation, unlike the previous recommendation, the airway sealing would be completed only by increasing the cuff pressure by approximately 4 cm H2O.

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