THE SIGNIFICANCE OF VITAL CAPACITY IN INTRATHORACIC THERAPY

PART I  Vital capacity, the largest expiration following the deepest inspiration, varies with age and sex, height and weight, health and disease, and after periods of rest and exertion. It is a fair criterion of life, reaching its peak when physiologic competence is highest, diminishing as incompetence increases and becoming zero when respiration ceases.A just evaluation of the therapeutic significance of vital capacity depends primarily on recognition of the anatomic and physiologic factors that establish it and secondarily on knowledge of their interrelationships, which control it. These are the means to understand the causes and effects of the numerous, considerable and at times abrupt fluctuations in vital capacity known to occur in health and in disease spontaneously and to be provoked by operations. They are also the means to better therapy.Answers to the questions implied are to be found in studies of the processes that control oxygen metabolism,