COPD and Human Diaphragm Muscle Dimensions

To assess the effect of COPD on diaphragm muscle dimensions, we measured diaphragm muscle mass, thickness, area, and lengths in 18 COPD patients at necropsy. We compared these results with data obtained from 22 non-COPD patients matched with regard to age, height, weight, and sex distribution. In the COPD patients, diaphragm muscle mass was 213 ± SD 69 g, thickness was .320±.055 cm, area was 647 ± 160 cm 2 , coronal muscle length was 27.8±4.0 cm and sagittal muscle length was 15.8±2.8 cm. These values were within ± 8 percent of the comparable values in the non-COPD patients, with no significant differences. There was no correlation between diaphragm length and lung volume in 13 COPD patients with TLC and ten with RV measurements. We conclude that over the range of lung volume encountered (TLC 135 ± 28 percent predicted, RV 102 ± 29 percent predicted TLC), there is no evidence for permanent shortening of the diaphragm.