Pulmonary Function Testing

Homeostatic mechanisms and the normal sizable cardiopulmonary reserve can combine to adjust ventilation and perfusion so that arterial gas tensions remain within normal physiologic limits, despite the presence of widespread lung disease and severe mechanical impairment of the respiratory apparatus. No single test of pulmonary function can give a reliable evaluation of a patient’s respiratory status, and a complete picture requires the assessment of as many indexes of respiratory function as possible.