Interpretation of respiratory functional explorations of deficiency and incapacity in adult.

Routine respiratory functional explorations (RFEs) performed as a part of the exploration of the respiratory deficiency include spirometry, plethysmography, bronchodilation test, measurement of the carbon monoxide diffusion capacity (DLCO), non-specific bronchial challenge (NSBC) and the measurement of the exhaled fraction of nitric oxide (FeNO). Functional exploration of disability is most often achieved by the 6-minute walk test (6MWT). All these RFEs were the subject of European and/or American consensus conferences in 2005 for the spirometry and plethysmography, in 2014 for the 6MWT, in 2015 for the FeNO, in 2017 for the NSBC and for the DLCO. The interpretation of the RFEs must therefore rationally be carried out according to the most recent international recommendations and requires reference to the lower and sometimes upper limits of normal (for spirometry, plethysmography, DLCO and 6-min walk distance), z-scores (for spirometry) or to fixed threshold values (for the bronchodilation test, FeNO and delivered dose of methacholine causing a 20% fall in forced expiratory volume in one second). Therefore, the main objective of this update was to expose the definitions and classifications of the various 'abnormalities' noted during the RFEs requested in the context of the exploration of the deficiency and incapacity of adult patients. This update will assist clinicians, especially pulmonologists, in the interpretation of the most commonly requested RFEs in practice.