Size of the diaphragm in chronic bronchitis

Abstract

Diaphragms were dissected out intact from 29 male and 9 female cadavers at necropsy. Fifteen of the males and eight of the females were grouped as controls, having no history of chest disease. Fourteen of the males and one female gave a history of chronic bronchitis. Point-counting and other methods were employed to measure the mean area, thickness, and volume of the diaphragmatic muscle, excluding the central tendon.The results showed t-hat the diaphragm was reduced in area, thickness, and volume in the chronic bronchitics, the figures being 350 cm2, 0 29 cm, and 99 7 cm3 respectively in male controls, and 295 cm2, 0-23 cm, and 68-7 cm3 in the bronchitics. In the female controls, the values were significantly lower than in the male controls. The one female bronchitic had a muscle volume of only 40 cm3. The male controls were similar in height to the bronchitics, but their mean weight was higher, being 69 4 kg against 56 0 kg in male bronchitics.It is concluded that the diaphragm is smaller in chronic bronchitics than in controls at necropsy and that while a major factor in causation is an associated low body weight, other factors such as the mechanical consequences of flattening of the diaphragm, longstanding reduction in physical activity, and other diseases such as cancer may also play a part. No histological changes by nonquantitative methods were found in the diaphragm in the chronic bronchitics, but muscle fibre shrinkage was suspected. By contrast, a few cases of asthma examined to date have shown no evidence of reduction in diaphragm size. The mechanical implications are discussed.Modern quantitative methods derived from the studies of geologists in the 1930s have been adapted by pathologists to measure changes in various tissue components in disease. In chronic bronchitis and emphysema, for example, the methods have been used to demonstrate enlargement of the bronchial mucous glands and hyperplasia of bronchial smooth muscle (Heard, 1969). The amount of emphysema in a specimen of lung can be measured accurately by a choice of several different procedures. Such information, especially when compared with clinical and physiological data from the same patients, is improving our understanding of chronic bronchitis and emphysema and helping to raise standards of treatment.

Diaphragm and body weight in emphysema.

“…They considered that the amount of emphysema in the lungs was not a significant variable affecting diaphragm weight. Steele and Heard (1973) also showed a positive correlation between body weight and diaphragm volume and thickness. The bronchitic patients were underweight but diminution of diaphragm volume was greater than could be accounted for by the loss of body weight.…”

“…Diaphragm weight was found diminished in an older study from Germany of six emphysematous subjects (Fromme, 1916). Steele and Heard (1973) felt that area, volume, and thickness of the muscular part of the diaphragm was decreased in 17 "chronic bronchitics" compared to 27 controls. They considered that the amount of emphysema in the lungs was not a significant variable affecting diaphragm weight.…”

Effect of Elastase-induced Emphysema on the Force-generating Ability of the Diaphragm

“…While studies of the dimensions of the human diaphragm in patients with chronic obstructive lung disease are conflicting (3,(43)(44)(45)(46)(47)(48), studies by Butler (43) and Steel and Heard (46) indicate that the area of the muscular portion of the diaphragm is reduced. Butler, in fact, showed that the reduction in area correlated directly with the extent of emphysema present.…”

Skeletal Muscles in Chronic Airflow Obstruction

“…The maintenance or increase in diaphragmatic mass may help counterbalance the adverse consequences of hyperinflation on the force generation. This finding is clearly at variance with patients with COPD in whom diaphragmatic atrophy is usual (3,8,9). This hypertrophic response, however, is neither universal nor always sufficient to fully restore diaphragmatic force production in all patients with cystic fibrosis; Pinet and colleagues (7) found, on average, a reduced diaphragmatic force in their patients.…”