Pulmonary Function Test

A pulmonary function test is a group of examinations that assess how well the lungs take in and expel air, as well as how well they move oxygen into the blood.

These tests can assist detect the reason of shortness of breath and may aid in the confirmation of lung diseases such as asthma, chronic bronchitis, and emphysema.

Purpose

• It aids in the diagnosis of a variety of respiratory diseases.
• The tests are also used to determine how the lung illness is progressing and how serious it has become.
• If you are experiencing signs of lung difficulties as part of a normal medical examination,
• To assess the efficacy of your medication if you have a lung condition such as asthma.
• To determine how well your lungs are functioning prior to surgery

Procedure

• PEFR (peak expiratory flow rate) is a measurement of airflow during forced expirations.
• The largest amount of air exhaled after taking a deep breath is measured by forced vital capacity (FVC).
• The forced expiratory volume in one second (FEV1) is a measurement of how much air can be expelled in one second.
• The maximum voluntary volume (MVV) is the quantity of air a person can inhale and exhale in one minute.
• Total lung capacity (TLC) is a measurement of how much air the lungs can contain.
• The amount of air left in the lungs following forced expiration is referred to as residual volume (RV).

A cystic fibrosis patient receives a pulmonary function test.

Arterial blood gas (ABG) tests the amount of oxygen and carbon dioxide in the blood and provides information about how well the lungs are working. Pulse oximetry tests the percentage of oxygen in the blood.

Spirometry is used to perform pulmonary function tests, with the exception of arterial blood gas, pulse oximetry, and total lung capacity (from the Greco-Latin term meaning "to measure breathing"). Spirometry tests can be performed at a hospital or in a doctor's office. The patient wears a clip over his or her nose and breaths via a tube into a machine called a spirometer. The patient takes a deep breath in and then exhales as quickly and forcefully as possible via the tube. The gadget measures the amount of air that flows through the tube. For the machine to function effectively, the exhalation must last at least six seconds.Usually, the patient repeats this test three times, and the best of the three results is considered the measure of the lung function. A similar machine called a peak flow meter may be used to measure PERF. Sometimes when airways are obstructed, the patient is given a bronchodilator, and the test is performed again.

Body plethysmography is used to determine total lung capacity. The patient sits in a telephone booth-like sealed chamber and breathes via a mouthpiece. During inhaling and exhale, a gadget measures the changes in air pressure in the box. The entire capacity of the lungs can be determined using these air pressure values.

Arterial blood gasses are determined using a blood sample drawn from an artery. Pulse oximetry measures the amount of oxygen in the blood using a sensor placed on the earlobe or fingertip.

When pulmonary function tests are combined, they provide a good picture of how much air is moving in and out of the lungs, as well as how efficiently oxygen is moved into the blood and carbon dioxide is moved out. Some of these tests are used as part of routine health screenings, while others are used to assess the condition of diseased or damaged lungs.

Precautions

Except for arterial blood gas testing and pulse oximetry, pulmonary function tests should not be performed on patients who have recently had a heart attack or who have certain other types of heart disease. Conditions that cause pain when breathing, such as broken ribs, may interfere with the tests' performance and result in erroneous results. Children must be of sufficient age to follow instructions and inhale and exhale as directed.

Preparation

The patient should not eat a heavy meal or smoke for four to six hours before the test. Before the test, the doctor will give you specific instructions on whether or not to take any medications.

Aftercare

No special aftercare is needed following these tests.

Risks

Risks with these tests are minimal. However, some people become lightheaded or faint. The tests may also trigger an asthma attack in individuals with asthma.

References

• emedicine.medscape.com/article/303239-overview
• www.healthline.com/health/pulmonary-function-tests
• https://www.nhlbi.nih.gov/health/health-topics/topics/lft
• www.webmd.com/lung/lung-function-tests
• http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/pulmonary/pulmonary-function-testing/
• www.news-medical.net/health/What-is-Pulmonary-Function-Testing.aspx
• www.metrohealth.org/pulmonary-function-test-pft