Chest mechanics after endoscopic lung volume reduction: Comparison between responders and non-responders based on dynamic hyperinflation.

BACKGROUND

Endobronchial lung volume reduction (ELVR) improves lung function, exercise capacity, and quality of life in case of severe emphysema. Nevertheless, not all patients are improved by ELVR including those with substantially decreased lung volume. We tested the hypothesis that unilateral volume loss could impact differently both responders and non-responders.

METHODS

A retrospective analysis was performed on 20 patients, classified as 13 responders and 7 non-responders based on inspiratory capacity increase ≥200 ml at isotime. We compared changes in lung volume, diaphragm shape and strength, mediastinal shift, lung function, exercise capacity, and quality of life before and three months after ELVR.

RESULTS

Compared to non-responders, responders showed a more improved diaphragm strength (4 vs. 2 cmH2O, p = 0.0318) and shape in both sides (non-treated side total area: +42 (7-54) cm2, p = 0.0079, non-treated side zone of apposition: +26 (18-52) cm2, p = 0.0270). Responders had a larger mediastinal shift than non-responders (13 vs. 3 degrees, p = 0.0039) with significant positive correlations between mediastinal shift and improvements in lung function (FEV1: r = 0.48, p = 0.0365), exercise capacity (6MWD: r = 0.78, p < 0.0001, inspiratory capacity: r = 0.48, p = 0.0365), and quality of life (CAT: r=-0.58, p = 0.0096).

CONCLUSIONS

Dynamic hyperinflation responders present a larger mediastinal shift than non-responders. This shift could be a marker of improved diaphragm shape and strength in both treated and non-treated sides.

CLINICAL TRIAL REGISTRATION: NCT05799352.