Procedures & Tests - Lung Function Tests

(This procedure/test may also be known as: Pulmonary Function Test, PFT)

Lung function tests are a group of tests that measure how well the lungs take in and release air and how well they move gases such as oxygen from the atmosphere into the body's circulation. These tests, also known as pulmonary function tests or PFTs, assist doctors in the diagnoses and management of lung diseases such as asthma and cystic fibrosis.

Types of PFTs

Spirometry is the first conventional test most children can do. In a spirometry test, you breathe into a mouthpiece that is connected to an instrument called a spirometer. The spirometer records the amount and rate of air that you breathe in and out over a period of time.

A child must be able to follow simple directions, make a seal with his mouth around the mouthpiece and forcibly exhale (breathe out). Spirometry can answer questions about obstruction, response to bronchodilator or exercise, and change over time. It can suggest, but not diagnose, restriction.

Children too young to perform spirometry may do impulse oscillometry. The child only has to be able to breathe with the mouth sealed around the mouthpiece. This test measures airway resistance and can look for bronchodilator responsiveness.

Maximum voluntary ventilation (MVV) looks at how much air can be moved in 30 seconds and may show impairment in weak individuals who can muster a forced exhalation.

MEP and MIP (maximal expiratory and inspiratory pressures) are tests of muscle strength.

Lung volume determination is necessary to diagnose restriction. The child must be able to sit in the body box with the door closed, make a seal at the mouthpiece and pant.

Diffusion capacity for carbon monoxide (DLCO) looks at movement across the alveolar capillary membrane to the RBC. The child must be able to follow directions and a current hemoglobin is necessary. This is the most sensitive test for damage caused by chemotherapy, other drugs, and for some interstitial and connective tissue diseases.

Exercise challenge measures spirometry before and after exercise, after recovery and, if indicated, bronchodilator. This can help determine if exercise symptoms are due to asthma.

In addition to being able to perform spirometry, the child must be able to walk on the treadmill, including wearing appropriate footwear. If heart disease or arrhythmia is a concern, an exercise test in cardiology should be ordered.

Methacholine challenge measures spirometry before and after increasing doses of methacholine. This test uses an aerosolized challenge agent called methacholine to determine airway reactivity. The baseline FEV1 must be at least 70% predicted prior to the test.

Pulmonary Function Lab

Related Conditions

Related Conditions
Here are some of the conditions related to this procedure/test. Select a condition to get more information and resources: Asthma, Cystic Fibrosis.

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