[From interpretation of cardiopulmonary exercise testing to medical decision]

Exercise is a situation that involves cardiovascular, respiratory and metabolic responses simultaneously. Thus, interpretating the results of the cardiopulmonary exercise testing (CPET) requires an integrated understanding of the pathophysiology of exercise intolerance which may result from lung, heart, pulmonary or peripheral circulation, muscles disturbances, or a combination of these functional disorders. In this paper, we offer a systematic method to assist clinicians in developing a pathophysiological reasoning from the functional competency of each component measured during incremental exercise. We propose to go through four steps: descriptive analysis, prioritization of the functional disorders, mechanistic proposals and diagnostic and/or therapeutic suggestions. The descriptive analysis step should answer seven key physiological questions, the prioritization step is based on the magnitude of the functional disorders and their relevance to the primary symptoms causing exercise intolerance, the mechanistic proposals step aims at suggesting different mechanisms and etiologies compatible with the scale of observed functional abnormalities, which will finally be tested by exploring specific diagnostic or therapeutic suggestions.