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Medical Dictionary
Work of Breathing
Respiratory muscle contraction during inspiration. The work is accomplished in three phases: that required to expand the lungs against its elastic forces (LUNG COMPLIANCE work), that required to overcome the viscosity of the lung and chest wall structures (tissue resistance work), and that required to overcome airway resistance during the movement of air into the lungs (AIRWAY RESISTANCE work). Work of breaking does not refer to expiration, which is entirely a passive process caused by elastic recoil of the lung and chest cage. (Guyton, Textbook of Medical Physiology, 8th ed, p406)
