A biologic aphorism, no life without breathing, indicates in a general way the importance of respiration. Activities sufficient merely to support life or to realize the utmost physical and mental powers, including defense and repair, are produced by metabolic processes which are dependent primarily on oxidation. This explains why man, although he may survive for weeks without food and for days without water, can exist for only a few minutes deprived of air. It also explains why any reduction in supplies of oxygen to the body, in deliveries of oxygen throughout the body and in utilization of oxygen by the body imposes a corresponding degree of disability.
The many diseases affecting the thorax and its contents, the enormous totals of transient and permanent disabilities and the large number of deaths they cause constitute a serious problem. More effective therapy is needed to provide greater limitations of disability and to reduce
YATES JL. THE SIGNIFICANCE OF VITAL CAPACITY IN INTRATHORACIC THERAPY. Arch Surg. 1925;10(1):477-505. doi:10.1001/archsurg.1925.01120100489027