The major object of the pulmonary function teste as preoperative examination in the pulmonary surgery is to valuate the pulmonary functional reserve, in particular, functional reserve of the pulmonary vascular bed and of ventilation.
The authers think it most useful to measure % vital capacity and timed vital capacity, to conduct bronchospirometry and unilateral pulmonary artery occulsion for testing pulmonary function as screening tests for surgery-indication of far-advanced pulmonary tuberculosis and consider it most reasonable to obtain the rate of the maximum expiratian for 3/4 second in the timed vital capacity measurement.
It is usually considered that the pulmonary functional reseve is two times as much as the work of the lung at rest on the ground that, for one thing, as hemodinamic studies show, no change can be witnessed in exercise test of pulmonary arterial pressure until cardiac output reaches tribble its amout at rest, and, on the other, as is commonly known through clinical experiences, post-operative, cardiopulmonary emergency is apt to happen when % vital capacity lowered to about 30.
In the circumstances, it can be said that no operation would be impossible, if a functionally intact portion of lung be preserved by approximately 30%, but, practically speaking,35% of the % vital capacity is the minimum that is required for the social life of the patient.
