Pulmonary function tests provide measures of airflow Airflow, Lung Volumes, and Flow-Volume Loop Airflow and lung volume measurements can be used to differentiate obstructive from restrictive pulmonary disorders, to characterize severity, and to measure responses to therapy. Measurements... read more 
, lung volumes Airflow, Lung Volumes, and Flow-Volume Loop Airflow and lung volume measurements can be used to differentiate obstructive from restrictive pulmonary disorders, to characterize severity, and to measure responses to therapy. Measurements... read more , gas exchange Measurement of Gas Exchange Gas exchange is measured through several means, including Diffusing capacity for carbon monoxide Pulse oximetry Arterial blood gas sampling The diffusing capacity for carbon monoxide (DLCO)... read more , response to bronchodilators, and respiratory muscle function Tests of Respiratory Muscle Function Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) measurements may aid in evaluating respiratory muscle weakness. MIP is the pressure generated during maximal inspiratory... read more .
Basic pulmonary function tests available in the ambulatory setting include
Spirometry
Pulse oximetry
Spirometry and pulse oximetry Pulse Oximetry Gas exchange is measured through several means, including Diffusing capacity for carbon monoxide Pulse oximetry Arterial blood gas sampling The diffusing capacity for carbon monoxide (DLCO)... read more 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
Lung, chest wall, and respiratory system compliance (which requires measurement of esophageal pressure)
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 Evaluation of the Pulmonary Patient Key components in the evaluation of patients with pulmonary symptoms are the history, physical examination, and, in many cases, a chest x-ray. These components establish the need for subsequent... read more 
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