Variations in the Carbon Dioxide Tension in the Arterial Blood and the Electrocardiogram in Man¹

On two subjects it is shown, that voluntary hyperventilation in atmospheric air brings about distinct electrocardiographic signs of myocardial hypoxaemia when the carbon dioxide tension in the alveolar air, and therefore also in the arterial blood, is reduced to about 20 mm Hg. It is pointed out that these findings may be of practical importance for the diagnosis of coronary insufficiency by the aid of electrocardiographic tracings after muscular work, or during respiration of a mixture of air poor in oxygen and carbon dioxide free, as these methods may cause an involuntary hyperventilation, and by this, a reduction of the carbon dioxide tension in the arterial blood.

Finally it is pointed out that these results argue in favour of using the hypoxaemia test and not the working electrocardiogram for the diagnosis of latent coronary insufficiency, and of using for the hypoxaemia test a mixture of air containing 2 or 3 per cent carbon dioxide in order to counteract the acapnia brought about by the hyperventilation.