Anoxemia in Pneumonia and Its Relief by Oxygen Inhalation.

Among those who have had most experience with the therapeutic use of oxygen in pneumonia, there seems at present to be fairly general agreement as to its value (1) (2) (3) (4) (5). The situation may perhaps be summed up this way: Oxygen in pneumonia is useful in so far as it can relieve or abolish anoxemia. It has no specific effect on the invading microorganism. It does, however, tend to restore to its normal state the internal environment of the host. This must be looked upon as an advantage in the patient's struggle for survival. There is ample evidence for the fact that acute anoxemia is harmful (6). When used early and continuously, and in the proper concentration, oxygen inhalation probably prolongs the patient's life. How often it actually is responsible for saving life it is impossible to state. Both the complexity and paucity of the material make statistical proof not only difficult to marshal, but of questionable value. An occasional brilliant recovery in a patient desperately ill with pneumonia, who has received oxygen treatment, seems a cogent argument in favor of the value of this form of therapy. But post hoc reasoning is not impregnable, and brilliant recoveries occur without oxygen. It may be wisest to be skeptical as to the life saving value of oxygen in pneumonia, but there can be no doubt that its use is indicated in the presence of anoxemia. Fortunately, we have a criterion for the efficaciousness of oxygen inhalation other than the survival of the patient. We refer to the effect on cyanosis, more particularly its effect on the oxygen content and per cent saturation of the arterial blood. The method of arterial