How should spirometry results be interpreted in pulmonary function testing?

Updated: May 14, 2020
  • Author: Kevin McCarthy, RPFT; Chief Editor: Nader Kamangar, MD, FACP, FCCP, FCCM  more...
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Interpretation of spirometry results should begin with an assessment of test quality. Failure to meet performance standards can result in unreliable test results (see the image below). The American Thoracic Society (ATS) defines acceptable spirometry as an expiratory effort that has the following characteristics:

Pulmonary function tests require patients to successfully perform respiratory maneuvers in a standardized manner in order to obtain clinically meaningful results. Spirometry is perhaps the most technically and physically demanding. The patient is required to inhale as fully as possible, exhale with as much force as possible, and continue their expiratory effort until they empty their lungs as completely as possible or are unable to continue.

The performance standards for acceptable spirometry are summarized below. The comments of the technologist administering the test can assist the interpreting physician in determining if results of a testing session that fail to meet some of the standards can still provide clinically useful data.

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