The Cardiac Output in Male Subjects as Measured by the Technique of Right Atrial Catheterization. Normal Values With Observations on the Effect of Anxiety and Tilting 1

Abstract

The determination of the cardiac output in man has usually been done by indirect methods. The demonstration (1) that mixed venous blood could be obtained by introducing a catheter into the right atrium and the later data (2), showing that this technique is simple and safe, have provided a new method for quantitative studies of the circulation in man. The purpose of this paper is to report the data obtained in the study of normal resting subjects by the catheter technique. Some of these persons were relaxed and quiet; others were nervous and apprehensive. METHODSPhysicians, medical students, hospital patients, and paid volunteers served as subjects. They had eaten no food since the evening meal 'on the night previously and they came to the laboratory at 7:30 a.m. After resting onehalf hour, the procedure was begun. Thirty to 90 minutes later, quantitative studies were made.The right atrium was catheterized via the median antecubital vein by the technique described by Cournand et al. (2 to 4). A slow drip of physiological saline solution was maintained through the catheter during the study. The necessity has been stressed (4) for having the tip of the catheter in the region of the tricuspid valve in order to obtain blood in which the streams from the superior and inferior cavae are fully mixed. Even with this precaution, a sample of mixed venous blood may not be obtained. In 3 subjects, blood from the atrium in the region of the tricuspid valve was found to have a very low oxygen content. Samples taken from the right ventricle or other parts of the atrium led to the conclusion that the catheter had entered the coronary sinus, or an aberrant hepatic vein emptying directly into the atrium.An inlying needle was placed in the femoral artery, which had previously been well novocainized. Oxygen consumption was measured by collecting ;expired air for 2-or 3-minute periods in a Douglas bag and analyzing its oxygen and carbon dioxide content by the method of Haldane. It was found necessary to bring in air from the outside of the building as the carbon dioxide content of the room air increased appreciably during the experiment. The metabolic rate was recorded as the percentage of deviation from the expected basal metabolism. The oxygen content of the mixed venous and arterial bloods was determined by the method of Van Slyke and Neill (5). The hemoglobin concentration of the blood was measured by diluting the blood with ammonia water and determining the intensity of the color by a photoelectric colorimeter. In the few instances where an arterial puncture was not done, blood from the atrium was saturated with oxygen and its oxygen capacity determined directly. The arterial oxygen content of the blood was then calculated on the assumption that the hemoglobin in the arterial blood was 95 per cent saturated with oxygen. It was not possible to calculate the oxygen carrying capacity of the blood from the concentration of the hemoglobin. Varying amounts of inactive hemoglobin were found in the blood. Similar observations have been ...

Cardiovascular Adjustments to Gravitational Stress

“…Many other investigators (21,24,119,120,287,309,345) have reported similar results. Stroke volume decreases in the upright position by about 33%.…”

The Cardiac Output in Patients With Arteriovenous Fistulas 1

“…We were fortunate, however, in that our patients returned to a normal state after operation without evidence of residual abnormality in the circulation. The postoperative cardiac index varied considerably from patient to patient, but the range was similar to that found in a comparable group of normal subjects studied by the catheter method (22). Therefore, we have utilized the value obtained postoperatively for each individual as his normal and have used this value as the basis of estimating the load placed on the heart by the fistula.…”

Correlative Observations on Cerebral Metabolism and Cardiac Output in Myxedema 1

“…Cardiac output was measured by the method of right heart catheterization utilizing the direct Fick principle (5,6). The was recorded with a Hamilton manometer.…”