Abstract
Background: Endotracheal tube (ETT) cuff leak in intubated patients is one of the leading causes of aspiration pneumonia and ventilator-associated pneumonia. The primary functions of the ETT cuff are to prevent air leak and minimize aspiration. The recommended cuff pressure ranges from 20 to 30 cm H2O. The purpose of this study was to evaluate the ETT cuff compliance change over time while maintaining the cuff pressure at 30 cm H2O. Methods: IRB approval was not required for this laboratory study. Under controlled conditions, the Laerdal Airway Management Trainer (Wappingers Falls, NY) was intubated with three different sizes of ETT (8.0,7.5, and 7.0) (Covidien/Medtronic, Minneapolis, MN). The depth of ETT was 22 cm at the incisors and the ETT was secured with regular ETT tape. A three-way stopcock was used with ports connected to the ETT pilot balloon, Posey Cufflator (Arcadia, CA), and 10 mL syringe. The cuff was inflated with the syringe until Cufflator reads 30 cm H2O of pressure. Volume of air needed to reach 30 cm H2O was recorded. The stopcock was removed and the Cufflator was subsequently used to check and maintain cuff pressure at 30 cm H2O every 6 to 8 hours. Same steps were repeated for 14 days for each ETT tube. Confidence intervals (CI) for the mean were calculated with a significant level of <0.58 for all 3 sets of sample data. Results: After 14 days of maintaining the cuff pressure at 30 cm H2O, all three ETT require more volume to maintain cuff pressure at 30 cm H2O (Figure 1). The size 8.0 ETT shows an increase of volume from 3.3 mL (day 1) to 5.9 mL (day 14). The size 7.5 ETT shows an increase of volume from 3.9 mL (day 1) to 4.3 mL (day 14). The size 7.0 ETT shows an increase of volume from 4.0 mL (day 1) to 4.8 mL (day 14). The calculated CI for ETT sizes 8.0, 7.5, and 7.0 are 0.54, 0.08, and 0.13 respectively. All three data sets show a significant volume change from day 1 to day 14. Conclusions: More cuff volume is needed to maintain the cuff pressure following sustained cuff inflation. Since compliance is determined by the volume and pressure, the volume increase at day 14 infers that the cuff compliance has increased over the course of 14 days. Routine use of the recommended cuff pressure should be done along with careful airway assessment in order to prevent inadvertent overinflation of the ETT cuff. A limitation of this study is that human subjects were not available due to IRB restrictions.
Figure 1 Volume of air needed to maintain cuff pressure at 30 cm H2O from day 1 to day 14
Footnotes
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