The Cardiovascular Effect of Induced Controlled Anoxemia

Abstract

Cardiovascular responses were studied by means of the ballistocardiograph and electrocardiograph in 16 normal subjects and 11 patients with suspected coronary artery disease before, during and after the induction of oximetrically controlled anoxemia. Progressive and significant increases occurred in cardiac output, pulse rate, left ventricular work, maximum cardiac force and pulse pressure during anoxemia in all of the normal subjects and in the 5 patients whose ballistocardiograms allowed the calculation of these variables. The increase in cardiac output resulted almost entirely from an acceleration of cardiac rate. In the normal subjects control ballistocardiograms were normal in form and remained normal throughout anoxemia. Of the patients, 1 with normal, 2 with borderline and 1 with abnormal ballistocardiograms became abnormal or more abnormal. Two of the patients had a positive electrocardiographic test for coronary insufficiency while the test was negative in all of the normal subjects. The linear relationship between left ventricular work and arterial oxygen saturation suggests that when cardiovascular function is tested by means of anoxemic stress the level of arterial desaturation should be controllable. This is made possible by the use of a variable oxygen-nitrogen mixture and an oximeter.