Reasons & Types of Lung Function Tests

Submitted on March 27, 2012

Lung Function Test

Lung function tests are also known as pulmonary function tests (PFTs). These tests can ascertain how well your lungs are functioning. Through these tests physicians can find out the amount of air that your lungs can hold, the speed with which the air moves in and out of the lungs, and how efficiently your lungs can breathe in oxygen, and flush out the carbon dioxide from your blood. Lung function tests are also done to diagnose lung diseases, check if a treatment for lung disease is working well or not, and check the severity of the lung problem.

Reasons to conduct Lung Function Test

Some of the lung function values that are measured are:

  • How much of air you can exhale with force after inhaling deeply.
  • How much of air you can exhale with force in a single breath.
  • What is the air flow like, halfway through an exhale.
  • How quickly you can exhale.
  • How much of air you can inhale and exhale in a minute.
  • How much of air you can breathe out after inhaling deeply.
  • How much of air is in your lungs after you've inhaled deeply.
  • How much of air is in your lungs after you have exhaled normally.

Tests to Check Lung Function

Some of the other tests to check the lung function include exercise stress tests, inhalation challenge tests, body plethysmography, gas diffusion tests, and residual volume.

Spirometry

Spirometry is another lung test that checks how quickly and how much of air you can move out of your lungs. You have to breathe into a mouthpiece that is attached to a spirometer, a recording device, and the printed information is known as a spirogram.

Gas diffusion tests

These tests are carried out to check the amount of oxygen as well as other gases that cross the air sacs of the lungs per minute. Through these tests, physicians are able to ascertain if the gases are absorbed into the blood from the lungs. Arterial blood gases tests are done to measure the amount of carbon dioxide and oxygen in your blood. Carbon monoxide diffusing capacity checks how efficiently the lungs transfer a bit of carbon dioxide into the blood.

Body plethysmography

This test is done to check the total lung capacity or the amount of air that the lungs can hold.

Residual volume or RV

In this test the residual air in your lungs are measured, after you exhale.

Inhalation challenge tests

If you have asthma or wheezing, then this test is done to check the response of your airways to allergens and the impact of methacholine and histamine on your airways.

Exercise stress tests

These tests are done to check the impact of exercise on some of the lung function tests.

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