To the Editor:—
The points in the letter by Dr. McClenahan are well taken. We believe the accuracy of the technique to be above reproach. The oxygen electrodes are calibrated using tonometered blood and results are checked frequently with other similar apparatuses in use throughout the medical center. In the future we may indeed have to revise our concepts of what a "normal" arterial oxygen tension is; certainly it appears to be lower in the geriatric age group than in the younger age group. Until further knowledge is obtained, it is our belief that one should strive for presently accepted normal, or above-normal, PO2 values in the postoperative period; these can be obtained in a majority of instances by the proper application of nasopharyngeal oxygen.