Endobronchial valve treatment improves diaphragm function in severe emphysema patients.

BACKGROUND

Diaphragm dysfunction is common in severe emphysema patients, primarily due to hyperinflation, placing the diaphragm at a mechanical disadvantage. Endobronchial valve (EBV) treatment is a bronchoscopic procedure to reduce hyperinflation and thus potentially restore diaphragm function in this patient population. Our aim was to investigate the effect of EBV treatment on diaphragm function.

METHODS

A prospective cohort study was performed in which diaphragm function was measured at baseline and 6 weeks after EBV treatment by ultrasonic assessment to measure diaphragm motion and diaphragm thickening fraction, surface electromyography (sEMG) to quantify diaphragm activity, and maximal inspiratory pressure to assess diaphragm strength.

RESULTS

25 patients were included, with a mean±sd age of 64±7 years. Mean±sd residual volume (-0.85±0.49 L; p<0.001) decreased significantly post-EBV treatment, with a significant increase in median (range) maximal inspiratory pressure (0.6 (-1.2-2.8) kPa; p=0.001). Median (range) diaphragm motion on the treated side during tidal breathing significantly decreased (-3.3 (-24.7-14.6) mm; p=0.023). There were no significant changes in diaphragm thickening fraction on the treated side. Median (range) diaphragm activity (sEMG) for tidal breathing (-1.7 (-8.8-5.8) µV; p=0.004), maximal inspiration (-4.1 (-42.3-16.0) µV; p=0.004) and sniff manoeuvre (-6.1 (-42.2-24.2) µV; p=0.027) all significantly decreased.

CONCLUSIONS

Our results show that diaphragm function significantly improves after EBV treatment in severe emphysema patients. This emphasises the physiological interaction between hyperinflation and diaphragm function, suggesting that reducing hyperinflation can at least partially reverse diaphragm dysfunction.