Measurement of endotracheal tube cuff leak to predict postextubation stridor and need for reintubation

The purpose of this study was to determine the predictive value of an endotracheal tube cuff leak for the development of postextubation stridor and the need for reintubation.

Consecutive trauma patients who required intubation at a level I trauma center from July 1997 to July 1998 were studied prospectively. Pediatric patients and those who did not meet the standard weaning protocol criteria established by the Division of Trauma and Surgical Critical Care were excluded. Injury Severity Score, endotracheal tube size, reason for intubation, and the number of days intubated before the initial extubation attempt were recorded. At the time of extubation, the difference in exhaled tidal volume from before to after endotracheal tube cuff deflation was calculated. This number was then divided by the exhaled tidal volume before cuff deflation and was recorded as the percent cuff leak. Patients were followed for 24 hours after extubation for the development of stridor or need for reintubation. Statistical analysis to compare subgroups of patients was performed using ANOVA with Scheffé post hoc analysis.

Among the 110 patients analyzed, the most common reason for intubation was closed-head injury. Seven patients (6.4%) developed stridor alone and had a mean cuff leak of 5 8 mL (8.4% of tidal volume before cuff deflation). Six patients (5.5%) experienced stridor that required reintubation and had a mean cuff leak of 68 mL (9.2% of tidal volume before cuff deflation). Patients who developed stridor or needed reintubation had been intubated for a significantly greater length of time than those not developing stridor or requiring reintubation (2.6 versus 3.0 days, p < 0.001). There were no differences in Injury Severity Score, endotracheal tube size, or reason for intubation between these groups.

A cuff leak of less than 10% of tidal volume before cuff deflation is useful in identifying patients at risk for stridor or reintubation (96% specificity). It appears that the amount of cuff leak decreases after intubation for more than 3 days, increasing the risk of stridor and need for reintubation. This information may be helpful in identifying those patients who need treatment for laryngotracheal edema, ie, use of steroids or anesthesia during extubation, the efficacy of which remains to be determined.