Tracheal tube obstruction in mechanically ventilated patients assessed by high-resolution computed tomography.

Background: Tracheal intubation compromises mucus clearance and secretions accumulate inside the tracheal tube (TT). The aim of this study was to evaluate with a novel methodology TT luminal obstruction in critically ill patients.

Methods: This was a three-phase study: (1) the authors collected 20 TTs at extubation. High-resolution computed tomography (CT) was performed to determine cross-sectional area (CSA) and mucus distribution within the TT; (2) five TTs partially filled with silicone were used to correlate high-resolution CT results and increased airflow resistance; and (3) 20 chest CT scans of intubated patients were reviewed for detection of secretions in ventilated patients' TT.

Results: Postextubation TTs showed a maximum CSA reduction of (mean±SD) 24.9±3.9% (range 3.3 to 71.2%) after a median intubation of 4.5 (interquartile range 2.5 to 6.5) days. CSA progressively decreased from oral to lung end of used TTs. The luminal volume of air was different between used and new TTs for all internal diameters (P<0.01 for new vs. used TTs for all studied internal diameters). The relationship between pressure drop and increasing airflow rates was nonlinear and depended on minimum CSA available to ventilation. Weak correlation was found between TT occlusion and days of intubation (R²=0.352, P=0.006). With standard clinical chest CT scans, 6 of 20 TTs showed measurable secretions with a CSA reduction of 24.0±3.9%.

Conclusions: TT luminal narrowing is a common finding and correlates with increased airflow resistance. The authors propose high-resolution CT as a novel technique to visualize and quantify secretions collected within the TT lumen.