Assessing the site of maximal obstruction in the trachea using lateral pressure measurement during bronchoscopy

Lateral airway pressure can provide valuable physiological information during bronchoscopy.

To evaluate tracheal obstruction during intervention.

To prospectively measure lateral airway pressure during bronchoscopy using a double-lumen catheter in 15 healthy subjects and 30 patients with tracheal obstruction. Pressure difference was used to evaluate the site of maximal obstruction. The angle between pressure recordings on either side of the stenosis was measured simultaneously (pressure-pressure curves) to assess the degree of tracheal obstruction.

In the experimental study, the angle of the pressure-pressure curve was unaffected by breathing maneuvers whereas the pressure difference was affected. In healthy subjects, no pressure difference between the carina and trachea was observed during tidal breathing, and the angle was close to 45°. In patients with tracheal obstruction, the dyspnea scale, pressure difference, and angle changed significantly beyond 50% obstruction (P<0.0001). After stenting, the pressure difference disappeared and the angle was close to 45°. The degree of tracheal obstruction was significantly correlated with the pressure difference (r=0.83, P<0.0001) and angle (r=-0.84, P<0.0001). The cross-sectional area, dyspnea scale, pulmonary function tests, pressure difference, and the angle significantly improved after procedures (P<0.0001). Responder rates on the modified Medical Research Council Scale were 84.6% for obstructions above 80%, and 58.8% for obstructions between 50 and 80%.

The direct measurement of pressure difference and the angle of the pressure-pressure curve represent a new assessment modality for the success of interventional bronchoscopy. Measuring lateral airway pressure could estimate the need for additional procedures better than bronchoscopy alone.