C73-22 Improvement Of The Mechanical Coupling Between The Rib Cage And Inspiratory Intercostal Muscles After Endoscopic Lung Volume Reduction

Rationale

Hyperinflation induces a cranial displacement of the ribs by reducing the ability of inspiratory intercostal muscles to generate inspiratory pressure due to muscle shortening. Endoscopic lung volume reduction (ELVR) aims at reducing lung hyperinflation, thereby improving respiratory mechanics. However, the effects of ELVR on the rib cage as well as on the inspiratory intercostal muscles have not been properly investigated. We used computed tomography (CT) to investigate the rib cage, the parasternal, and the external intercostal muscles, before and after ELVR.

Methods

This is a prospective monocentric study that included 35 COPD patients treated by ELVR with endobronchial valves between April 2025 and December 2025. The rib cage shape and the length of parasternal and external intercostal muscles were evaluated by CT and 3D slicer before and three months after valves insertion.

Results

Statistically significant caudal displacements of the anterior part of ribs two to seven (-6% [-2 - -10] in average; p ranging from 0.019 to 0.039) and of the lateral part of the second and third ribs (-14% [-9 - -32] in average; p ranging from 0.006 to 0.011) were observed on the treated side. These caudal displacements were associated with an increase in parasternal muscle length in all intercostal spaces (+4% [1-10] in average; p ranging from 0.001 to 0.018)as well as an increase in external intercostal muscle length in the second and third intercostal spaces (+10% [1 - 14] in average; p ranging from 0.032 to 0.049).

Conclusions

ELVR improves the mechanical coupling between the ribs and inspiratory intercostal muscles by inducing a caudal displacement of the upper ribs and increasing the length of the parasternal and principal external intercostal muscles.

This abstract is funded by: None