Endotracheal tube intraluminal volume loss among mechanically ventilated patients

Objective: To measure endotracheal tube intraluminal volume loss among mechanically ventilated patients. Design: Prospective observational study. Setting: Medical intensive care unit (19 beds) of an urban university-affiliated teaching hospital. Patients: A total of 101 patients with acute respiratory failure requiring > 24 hrs of mechanical ventilation. Interventions: None. Measurements and Main Results: Acoustic reflectometry was employed to measure the intraluminal volume of 13-cm endotracheal tube segments. The endotracheal tube segment volumes were statistically smaller among endotracheal tubes used in patients compared with unused endotracheal tubes (5.4 +/- 0.7 vs. 6.0 +/- 0.6 mL, p < .001). The average percentage difference in endotracheal tube segment volumes, between the unused endo-tracheal tubes and the endotracheal tubes used in patients, was 9.8% (range, 0-45.5%). The percentage difference in the endotracheal tube segment volumes increased significantly with increasing duration of tracheal intubation (r(2) = .766, p < .001). The minimum diameter of the endotracheal tube segments was also statistically smaller among endotracheal tubes used in patients compared with the unused endotracheal tubes (7.5 +/- 0.4 vs. 6.7 +/- 1.2 mm, p < .001). Conclusions: Endotracheal tube intraluminal volume loss is common among patients with acute respiratory failure requiring mechanical ventilation and increases with prolonged tracheal intubation.