CLINICAL STUDIES OF THE RESPIRATION. VII

Abstract

The clinical significance of spirometry in disease was recognized more than sixty years ago, but in the last decade little attention has been devoted to its practical application.Recently, however, a number of studies on the respiration have again indicated that the character and possible extent of the pulmonary ventilation are intimately related to the vital capacity of the lungs, and that determination of the vital capacity gives important information as to the functional efficiency of the lungs.Clinical observations have shown that the vital capacity of the lungs is of especial interest in pulmonary tuberculosis 1 and in heart disease,2 and that in both these conditions it serves as an index of the clinical condition of the patient.As the disease becomes more severe, the vital capacity falls, and as the disease improves, the vital capacity increases and approaches the normal.In pulmonary tuberculosis and in the other inflammatory or infiltra- tive lesions of the lung substance, as well as in conditions which, like pleural effusion, interfere with the movements of the lungs, it is quite easy to understand why the vital capacity is reduced.In heart disease the circumstances are often less simple.The tendency to dyspnea on exertion increases progressively as the vital capacity falls, and there is abundant evidence to indicate that the interference with pulmonary ventilation is an important factor in producing dyspnea, but, partic¬ ularly in the early stages of heart disease, an increased tendency to dyspnea associated with a decrease in vital capacity may be present without any physical signs of involvement of the lungs or pleural