Lung Function in Patients with Systemic Sclerosis

Scleroderma is a chronic disease of unknown aetiology, usually classified with the collagen diseases. Raynaud's phenomenon occurs in a high proportion of cases. The most obvious manifestations are in the skin, but other organs may be involved, notably the lungs, heart, gastrointestinal tract, and kidneys. The term diffuse or progressive systemic sclerosis has been introduced to describe those cases showing visceral as well as cutaneous manifestations. The essential pathological features are swelling and disintegration of the collagen tissue accompanied by cellular infiltration and fibrosis; the process may also involve the intima of small vessels with fibrinoid necrosis and occlusion. Lung involvement in systemic sclerosis was first described at the end of the last century (Lewin and Heller, 1894), and there have been several more recent reports (Lloyd and Tonkin, 1948; Shuford, Seaman, and Goldman, 1953; Opie, 1955). The symptoms are usually breathlessness on exertion and cough producing scanty mucoid sputum. Examination may reveal clubbing of the fingers, basal crepitations, and often poor chest expansion, though some patients have no abnormal physical signs. The typical radiological appearance, first described by Murphy, Krainin, and Gerson (1941), is that of diffuse reticular shadowing, usually most pronounced at the bases. Some cases show a cystic appearance, and systemic sclerosis has been included among the causes of 'honeycomb lung' (Spain and Thomas, 1950; Hayman and Hunt, 1952). At necropsy the lungs show diffuse fibrosis involving the alveolar walls with obliteration of capillaries and alveolar spaces. Fibrosis can also involve the bronchial walls and peribronchial tissue. This may even lead to bronchiectatic areas, corresponding to the radiographic cystic appearance. Obliteration of the pulmonary vascular bed may result in pulmonary hypertension. Intercurrent chest infections may complicate the picture, especially in the presence of marked oesophageal involvement resulting in a 'spill-over', whilst involvement of the skin and possibly muscle of the chest wall may restrict movement. These pathological processes impair lung function in various ways. Deranged lung function in cases of systemic sclerosis has been recognized for some years with an alveolar-capillary block in many instances (Baldwin, Cournand, and Richards, 1949; Austrian, McClement, Renzetti, Donald, Riley, and Cournand, 1951). Very few measurements of the diffusing capacity have been reported, however. This paper presents the findings in 10 patients studied in this laboratory in whom the diffusing capacity was measured by the single breath technique of Ogilvie, Forster, Blakemore, and Morton (1957). Two additional patients studied by Dr. Colin Ogilvie in his unit have been included for comparison.