Utility of portable chest radiographs as a predictor of endotracheal tube cuff pressure

Increased endotracheal tube cuff pressure causes mucosal ischemia that can lead to necrosis, infection, and, eventually, tracheomalacia or tracheal stenosis. Endotracheally intubated patients frequently undergo portable chest radiography. In this study we explored the relationship of endotracheal tube cuff pressure and the appearance on the tracheal air columns on the portable chest radiograph. We measured the endotracheal tube cuff pressure of intensive care unit patients 124 times immediately before portable chest radiography. On 64 of these radiographs we measured the width of the tracheal air column below the tip of the endotracheal tube and at the maximal diameter of the endotracheal tube balloon. We then analyzed the relationship of cuff pressure to tracheal dilation. The results of ANOVA of tracheal dilation for three groups (safe, borderline, and unsafe cuff pressures) were significant. Large overlapping ranges existed in each group. Regression analysis confirmed a linear relationship between cuff pressure and tracheal dilation (r = 0.435, p < 0.001). Predicted tracheal expansion at 20 mm Hg was a poor screen for endotracheal tube cuff inflation safety; the sensitivity was only 56% and specificity only 71%. The differences in the capacity for tracheal distension between patients make these findings not unexpected. The portable chest radiograph is a poor screening tool for unsafe endotracheal tube cuff pressure.