The Relationship between the Arterial Oxygen Saturation and the Cardiovascular Response to Induced Anoxemia in Normal Young Adults

Abstract

The induced anoxemia test of cardiovascular function has been standardized according to the degree of anoxemia rather than the oxygen concentration of the gas mixture administered. The cardiovascular response of normal subjects at 80, 75 and 70 per cent arterial oxygen saturation is described. The changes can be closely correlated with the degree of anoxemia, as measured by the oximeter.AT THE present time the most widely used method of studying the effect of induced anoxemia on the cardiovascular system consists of giving the subjects low oxygen gas (usually 10 Each subject rested on a bed in a quiet room until his or her blood pressure and pulse rate became stabilized. Electrocardiograms were ma(le with a Cambridge electrocardiograph and standardized to give a 10-mm. deflection with 1 millivolt. In measuring the height of the RS-T segment, the P-Q or P-R segment was selected as the isoelectric line according to the method followed by Katz,4 Malmstrom,5 and others. Blood pressure was taken by the auscultatory method with a Tycos manometer; the heart rate was obtained from the electrocardiogram. The blood pressure, pulse rate, and electrocardiogram were taken before, during, and after the period of anoxemia.A total of 76 normal persons was studied. Seventytwo were medical students and the remainder. were laboratory assistants. All but 3 of the subjects were men. Seventy-three of the subjects were between 22 and 28 years of age; the other 3 subjects were 16, 17. and 34 years old. All subjects were of the white race and were free from any cardiovascular disease as far as could be determined by a preliminary examination, which included a detailed medical history, physical examination, and electrocardiogram. Eighty-one tests were performed on the 76 subjects. In most instances the arterial oxygen saturation was lowered in a "step-wise" manner3 so that a subject was studied at more than one level of saturation during the same test. The various readings (electrocardiogram, etc.)

Calibrated Hypoxemia Test in Normal Subjects and Coronary Patients

“…Other workers have confirmed that the T wave is reduced in normal subjects in hypoxemia (12,16,21). This T reduction has been observed in normal subjects even at an arterial saturation of between 70 and 80 % (17).…”

Effects of acute hypobaric hypoxia on thermoregulatory and circulatory responses during cold air exposure

“…Penneys and Thomas [18] have reported a relationship between SpO 2 with heart rate and blood pressure, respectively, in normobaric hypoxia without thermal stress. In this study, we only found a relationship between SpO 2 and PR.…”