Tidal volume - Definition

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Tidal volume, or TV, is the volume of air inhaled or exhaled with every respiratory movement. This measure is taken by means of spirometry, the study of pulmonary ventilation, performed as part of standard pulmonary function tests, or PFTs. The patient is placed in a small room and breathes through a nozzled tube linked to a machine, which is in turn linked to a screen that displays curves corresponding to the respiratory volumes. These results enable us to assess the respiratory function of the patient, thus revealing suspected conditions or used to monitor them. The principal conditions leading to a decreased tidal volume are COPD, or chronic obstructive pulmonary disease, chronic respiratory failure in cases of chronic pulmonary disease, or pulmonary emphysema.