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Pulmonary function tests
Make it clearer
Pulmonary function tests are not one test: they are a family. They are used to assess how breathing is working in many clinical situations, and also when there are risk factors for lung disease, workplace exposures, or lung toxicity from a treatment.
Each one looks at something different, like measuring a house three ways: how fast air moves through the door, how much air fits inside, and how well it crosses one very thin wall. Spirometry measures how much air you can move in and out over time. Lung volume measurement detects changes in how much air the lung holds, and it detects them even when a person's effort varies. And diffusing capacity measures how well gases cross the alveolar-capillary membrane, the extremely thin wall that separates the air in the alveolus from the blood in the capillary.
There is a limit worth being clear about. The result depends on the effort the person puts in, and on its own it does not give a diagnosis: it is read together with the history, the physical exam, and laboratory tests.
In brief
Pulmonary function tests assess breathing in the setting of risk factors, workplace exposures, or lung toxicity.
There are three measurements: spirometry measures how much air moves in and out over time, lung volumes detect changes independent of effort, and diffusion measures how gases cross the alveolar-capillary membrane.
One measures flow, another volume, and another the passage of gas into the blood.
The result depends on effort and does not give a diagnosis on its own: it is combined with history, physical exam, and laboratory tests.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPulmonary Function Tests, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated