The Oximeter-Controlled Induced Anoxemia Test: Seventy Tests on Coronary Suspects

Introduction  The observation that the inhalation of a gas of low oxygen content may bring on angina pectoris, or specific electrocardiographic changes, has led to the induced anoxemia (hypoxemia) test for the study of coronary artery disease.* The type of anoxemia test most widely used is that of Levy and co-workers, in which a gas of fixed low oxygen concentration, 10%, is administered for a period up to 20 minutes.²In two previous papers, with Dr. Caroline Thomas, we described another type of test, the oximeter-controlled anoxemia test,^3,4 in which the content of oxygen in the respired gas is varied to produce the desired degree of anoxemia, measured continuously by the oximeter.⁵ This overcomes the large variability in the oxygen saturation of the arterial blood known to result from the inhalation of 10% oxygen and other gas mixtures of fixed oxygen concentration.^3,4,6-8 In subsequent papers, with