Spirometry is the gold standard for identifying airway obstruction. The principal parameters used are forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and the FEV1:FVC ratio. When the FEV1:FVC ratio is reduced, the percent of predicted FEV 1 is used to grade the severity of airway obstruction. The appearance of the inspiratory and expiratory flow-volume loops can suggest disease patterns. For example, the inspiratory flow-volume loop is flattened in variable extrathoracic obstruction of the airway. In variable intrathoracic obstruction, the expiratory flow-volume loop is blunted. Vital capacity and FEV1 are used to gauge bronchodilator response; the postbronchodilator FEV 1 is a more stable parameter for serial comparison of obstruction.
|Number of pages
|Journal of Respiratory Diseases
|Published - Jan 1 2005
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine