Physiological concepts involved in pulmonary function tests

Abstract

Pulmonary function tests evaluate lung volumes and capacities, airway resistance, and the response of the respiratory system to exercise. The objective of this article is to approach physiologically the performance and interpretation of: dynamic test, flow-volume curve and 6-minute walk test. The dynamic test and the flow - volume curve reflect the resistance of the airway, factors that influence resistance will affect the results of these tests. Exercise produces an increase in pulmonary blood flow and alveolar ventilation, events that normally do not produce disturbances in conduction and diffusion of O₂ to tissues and CO₂ into alveolar air.  The 6-minute walk test does not allow to identify the causes of exercise limitation, but it allows the global assessment of exercise tolerance.