Abstract :
B. L. Vosburgh (nonmember; General Electric Company, Schenectady, N. Y.): According to Burton Opitz´ physiology a full-grown man inspires and expires about 500 cubic centimeters of air with each respiratory act. This figure compares favorably with the average of the 15 subjects in the prone position, namely 545 cubic centimeters and 590 cubic centimeters for subjects A, B, and C. When anesthetized this tidal air volume dropped to 264 cubic centimeters average with the minute volume at 4,752 cubic centimeters compared to 7,670 cubic centimeters in the wakeful state which is a decrease of about 60 per cent per respiration and 30 per cent per minute volume. This remarkable difference holds for all comparisons between the conscious and anesthetized state and must mean a lessened metabolic demand in the latter. It is quite likely then that 350 to 400 cubic centimeters of air would meet adequately the anesthetized subjects needs for oxygen. Instead we note 590 for the original Schafer method, 746 for the modified Schafer, and 799 for the pole-top method. These figures represent a surplus air intake of from 60 to 100 per cent beyond metabolic requirements. This means hyper-ventilation with consequent lowering of the blood carbon dioxide, which, of course, depresses central stimulation of respiration. This effect might well tend to prolong a paralysis of respiratory function.
