Expiratoire

Expiratoire is a French adjective that denotes a relation to expiration, the phase of breathing during which air is expelled from the lungs. It is used in physiology and medicine to describe processes, measurements, and structures associated with exhalation, in contrast to inspiratoire, which pertains to inhalation.

In the respiratory cycle, the expiratory phase can be passive or active. Terms such as phase expiratoire, débit expiratoire (expiratory flow) and volume expiratoire (expiratory volume) are common. In clinical practice, expiratory measurements are central to spirometry, with indices like volume expiratoire maximal (VEM), volume expiratoire forcé (VEF, or forced expiratory volume), and débit expiratoire de pointe (peak expiratory flow). Functional assessment often relies on the ratio of expiratory volumes to identify obstructive or restrictive patterns, for example using the relation between VEMS (volume expiratoire maximal sec) and CVF (capacité vitale forcée).

Anatomically and physiologically, expiration involves both passive recoil of the lungs and chest wall and, during forced expiration, active contraction of expiratory muscles such as the internal intercostals and the abdominal wall muscles. This active component increases expiratory flow during activities like coughing, exercise, or rapid breathing.

Expiratoire is thus a key term in describing and analyzing the mechanisms and measurements of exhalation, and it is commonly paired with terms referencing inspiratory processes to distinguish phases of the respiratory cycle. See also inspiration, respiration, and spirométrie.