Effects of lung volume reduction surgery for emphysema on diaphragm dimensions and configuration

Part of the functional benefit provided by lung volume reduction surgery (L VRS) may be related to improvement in respiratory muscle function resulting from changes in diaphragm dimension and configuration. To study these chan ges, we obtained 3D reconstructions of the muscle using spiral computed tom ography in 11 patients with severe emphysema before and 3 mo after surgery, and in 11 normal subjects matched for sex, age, height, and weight. Bilate ral LVRS was performed by thoracoscopy in eight patients and by sternotomy in three patients. Acquisitions were made in the supine posture at relaxed FRC, midinspiratory capacity, and TLC. On average, LVRS produced a 51 +/- 1 1% increase in FEV1 and a 30 +/- 4% decrease in FRC. The total surface area of the diaphragm (A(di)) and of the zone of apposition (A,p) at FRC increa sed by 17 +/- 4% and 43 +/- 8%, respectively, but the surface area of the d ome did not change. Compared with the values recorded in the normal subject s, postoperative values of A(di) and A(ap) at FRC were reduced by 11%(p < 0 .05) and 24% (p < 0.005), respectively. The curvature of the dome increased at TLC in the left sagittal plane, but was otherwise unaffected by the pro cedure. We conclude that LVRS substantially increases A(di) and A(ap,) but does not significantly improve diaphragm configuration at FRC.