Pulmonary function tests provide measures of airflow, lung volumes, gas exchange, response to bronchodilators, and respiratory muscle function.
Basic pulmonary function tests available in the ambulatory setting include
Spirometry
Pulse oximetry
Spirometry and pulse oximetry provide physiologic measures of pulmonary function and can be used to quickly narrow a differential diagnosis and suggest a subsequent strategy of additional testing or therapy. More complicated testing includes
Measurement of lung volumes (plethysmography, nitrogen washout, helium dilution)
Measurement of lung, chest wall, and respiratory system compliance and resistance (maximal voluntary ventilation and respiratory pressures)
Bronchoprovocation challenge (exercise, methacholine challenge)
Complete cardiopulmonary exercise testing
These tests provide a more detailed description of physiologic abnormalities and the likely underlying pathology. The choice and sequence of testing are guided by information taken from the history and physical examination.
