To the Editor.—
The recent article by Petty et al in the January Archives (139:28-32, 1979) does not point out certain important guidelines for oxygen therapy, and also leaves out the role of oxygen in other situations. This is all extremely important at this time, since it has come to our attention that third-party payers (Medicare and others) seem to be using articles such as this as the basis for oxygen therapy.The initial effects of oxygen devices on patients should be monitored by taking into consideration the patient's complete disease state (pulmonary, cardiac, cerebral), his minute ventilation, the inhaled oxygen concentration (FIO2), the face apparatus used in giving the oxygen, and the resultant arterial Po2. The presently available oxygen concentrators (seven in all) produce less than 100% oxygen, usually 55% to 93%, with one producing 40% oxygen. When used with humidifiers, in different subjects, and with different