Pulmonary dysfunction in systemic lupus erythematosus without pulmonary symptoms.

Pulmonary function was measured in a group of 28 patients with systemic lupus erythematosus (SLE) who were free of pulmonary involvement at the time of the study. When compared with age and sex matched controls, the SLE patients had a pattern of restriction with reduced lung volumes and vital capacity. Diffusing capacity was reduced in proportion to the reduction in lung volume. This is felt to be most compatible with inapparent pleural thickening resulting in impaired lung expansion. There was no evidence of airway obstruction on maximal expiratory flow-volume curves. The effect of cigarette smoking in the SLE patients was a reduction in flows at low lung volumes, which was indistinguishable from the effects in the control smokers. Both SLE and control smokers had a significant reduction in DL/VA when compared with control nonsmokers. Pulmonary function was not influenced by the presence of renal disease.