STUDIES OF CONGENITAL HEART DISEASE. II. THE PRESSURE AND OXYGEN CONTENT OF BLOOD IN THE RIGHT AURICLE, RIGHT VENTRICLE, AND PULMONARY ARTERY IN CONTROL PATIENTS, WITH OBSERVATIONS ON THE OXYGEN SATURATION AND SOURCE OF PULMONARY “CAPILLARY” BLOOD 1

Abstract

Venous catheterization of the venae cavae, right auricle, right ventricle, and pulmonary artery has been performed in control patients with various diseases but without congenital defects affecting the facto; studied. Pressures and multiple samples of blood for oxygen analysis have been obtained from each chamber. The greatest increase in oxygen from the superior vena cava to-the right au-ricle was 1.9 vol.%; from the right auricle to the right ventricle, 0.9 vol. %; and from the right ventricle to the pulmonary artery, 0.5 vol. %. The systolic pressure in the pulmonary artery was almost identical with that in the right ventricle over a wide range of pressures. Arterial blood may be obtained from the distal branches of the pulmonary artery by obstructing the artery with the catheter and withdrawing blood through the catheter lumen. Evidence is presented indicating that this blood originates in the pulmonary capillary and venous bed rather than in precapillary anastomoses with systemic arteries. The O2 content of bloods obtained from several sites within the right auricle and right ventricle showed at times considerable variation, while those from the pulmonary artery were remarkably uniform. It is concluded that mixed venous blood for the detn. of cardiac output may be obtained consistently from the pulmonary artery but not uniformly from the right auricle and right ventricle.