Dickinson W. Richards

Some Effects of Digoxin upon the Heart and Circulation in Man Digoxin in Chronic Cor Pulmonale

The effects of acute digitalization upon the dynamics of the circulation were observed in patients with chronic cor pulmonale, using the technic of cardiac catheterization. The state of the circulation was further investigated in the same patients following recovery from failure. The mode of action of intravenous digoxin is discussed, and a tentative concept of the pathogenesis of chronic cor pulmonale is presented.

STUDIES ON INTRAPULMONARY MIXTURE OF GASES. IV. THE SIGNIFICANCE OF THE PULMONARY EMPTYING RATE AND A SIMPLIFIED OPEN CIRCUIT MEASUREMENT OF RESIDUAL AIR

In preceding papers of this series, we have studied (1) the relative effectiveness of mixing or distribution of tidal air into alveolar spaces in normal and abnormal subjects, and have proposed (2) an open circuit method for residual air determination, in which nitrogen in the lungs is washed out by continuous inhalation of pure oxygen. The present paper (a) gives the results of a number of determinations of residual air, by the open circuit method, in normal subjects and patients with chronic cardiac or chronic pulmonary disease; (b) offers certain simplifications of technique in the open circuit method; and (c) suggests further significance of some of the data which this method provides. It will simplify the succeeding discussion if a brief review is given of the theoretical basis of the open circuit method of residual air determination. The principle underlying all residual air methods which employ an inert gas, such as nitrogen or hydrogen, is the measurement of this inert gas before and after its distribution (by means of a period of breathing) between an unknown volume (the lungs) and a known volume (the spirometer). The relationship is described by a simple formula. Let nitrogen be the inert gas measured: (Nitrogen percentage in lungs at start X lung volume) + (nitrogen percentage in spirometer at start X spirometer volume) (nitrogen percentage in lungs at end X lung volume) + (nitrogen percentage in spirometer at end X spirometer volume). For purposes of simplification, the correction factor due to nitrogen excreted from the body (3) is here disregarded. Solving the above equation for lung volume,

Hemodynamic Studies in Rheumatic Heart Disease

Hemodynamic studies were made in 42 patients with rheumatic heart disease with various valvular lesions and in different stages of cardiac function. These studies include observations not only at rest, but also during exercise, following the acute administration of Digoxin, and after recovery from failure. The relationship between symptomatology and hemodynamic findings were considered and the importance of differentiating between mechanical block and left ventricular myocardial failure as causes for pulmonary artery hypertension is stressed.

The Lewis A. Conner Memorial Lecture The Nature of Cardiac and of Pulmonary Dyspnea

Dyspnea has many characteristics, differing from one clinical state to another. In pulmonary diseases the immediate cause is usually a disproportion between actual ventilation (breathing requirement) and breathing capacity. The hyperventilation of organic pulmonary disease is often mistakenly diagnosed as psychoneurosis. In early cardiac dyspnea, muscular fatigue associated with inadequate cardiac output may be a factor. True pulmonary congestion becomes important in more advanced left ventricular failure.