Affiliation:
1. Baylor College of Medicine, Houston, Texas 77030.
Abstract
Radiopaque markers were attached at 1- to 2-cm intervals along three nearby muscle bundles to cover rectangular regions of the mid-costal diaphragms of seven dogs. The markers were tracked by biplane video fluoroscopy during spontaneous breathing (SB), mechanical ventilation with the same tidal volume (MV), and at inflation to total lung capacity (TLC) in the prone and supine positions. The three-dimensional positions of the markers at functional residual capacity (FRC), at end inspiration during SB and MV, and at TLC were determined, and the strains in the plane of the diaphragm relative to FRC were calculated. The principal strains were found to lie nearly along the muscle bundle direction and perpendicular to it. The principal strains along the muscle bundles, which describe muscle shortening, were uniform among the three bundles and uniform along the bundle for MV. For SB, in the prone and supine positions, shortening was approximately 30% greater in the middle of the bundle than near the central tendon and chest wall. Although the tidal volumes were the same for SB and MV, the shortening was larger for SB. The strains perpendicular to the bundle direction were not significantly different from zero. It appears that, for the loads that occur during tidal breathing, the diaphragm is inextensible in the direction perpendicular to the muscle direction. There is a very small displacement of the costal diaphragm at its insertion on the chest wall. The displacement at the central tendon is primarily a result of muscle shortening and rotation of the arc of the muscle around its insertion on the chest wall.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Cited by
32 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献