Pulmonary function tests refer to a group of test that are conducted to determine the basic functionality of the lungs that involves the intake and release of air as well as the regulation and circulation of atmospheric gases such as oxygen within the body.
Many individuals are easily confused by the need for pulmonary function tests. Patients with cardiac conditions are usually aware of their cholesterol levels and their blood pressure numbers. But many of us tend to overlook the numbers that are associated with chronic obstructive pulmonary disease or COPD or with pulmonary function tests or PFTs. It is essential to remember that such numbers are equally important to know, and be aware of.
There are many programs that encourage the patients to undergo pulmonary function tests and become aware of their respective numbers. The National Lung Health Education Program has come up with the slogan ‘Test your lungs; know your numbers’ to promote awareness about the need for such tests. Such programs also encourage the general use and practice of spirometry tests by doctors, since reports indicate the use of such tests by doctors are as low as 30 percent, in the current medical environment.
When the patient is aware of the pulmonary function tests’ numbers, he/she can become one’s own doctor and monitor the health. The patients can compare the results of the test to identify whether the underlying disease is responding to treatment and also whether the condition is progressing.
The need for pulmonary function tests
While diagnosing COPD, the degree of damage to the lungs as well their altered functionality are assessed by pulmonary function test. Various tests such as lung imaging studies, the patient’s medical history, open lung biopsy, etc. are performed to determine and evaluate the respiratory health of a patient. Pulmonary function tests are an addition to such tests and have rapidly become very important.
There are a wide variety of uses for pulmonary function test. Some of them are listed below:
- To determine the medical health of the patient before surgery and in assessing the risk to complications of the respiratory system post surgery.
- To access the progress of lung disorder and to evaluate the efficacy of the treatment employed.
- To screen and check whether any lung disease are present
- Determining the ability of an individual to be weaned from the ventilator
Diagnosis of COPD involves three types of pulmonary function tests which are body plethysmography, diffusion studies and spirometry testing.
Body Plethysmography
This test is used to determine the amount of air that is available in the lungs at the time of deep inhalation and the amount of air that is left in the lungs after as much exhalation of air as possible.
Diffusion Studies
This pulmonary function test is used to determine the efficacy of movement of the oxygen that is inhaled, within the bloodstream.
Spirometry testing
The spirometry test is the most common form of pulmonary test that is employed by doctors. A handheld gadget called a spirometer is used to perform the test. Patients can easily use the device to conduct tests with the help of a technician who has experience in using it. The spirometry test is the premier choice of all clinicians and diagnostic centers when they are trying to diagnose any form of respiratory condition. It is a non-invasive and comfortable procedure which can be conducted privately in your physician’s office or some other outpatient or inpatient facilities.
In spirometry, the patient needs to deeply inhale after expelling all the air from one’s lungs. The deep inhalation of air is then followed by such swift exhalation that results in rapid exhaustion of air from the lungs.
Spirometry tests yield results of many variations, but are compared against the predicted values and data obtained from a standardized, healthy section of the population.
Individuals affected by COPD tend to exhale air from the lungs in smaller quantities and at a slower rate in comparison to other normal and healthy individuals. There are many reasons that may prevent the ready exhalation of air from the lungs of patients affected by COPD and other lung diseases. The causes could be obstruction of the respiration system due to excessive mucus production or narrowing of the airways due to prolonged inflammation.
Mentioned below are some common terminology used in spirometry tests and are crucial in COPD diagnosis.
- FVC-Forced Vital Capacity: The quantity of air that can be exhaled forcibly from one’s lungs after the intake of the deepest possible breath
- VC-Vital Capacity: the quantity of air that can be exhaled forcible from the lungs after a complete inhalation
- Forced Expiratory Volume in One Second or FEV1: This refers to the quantity of air that is exhaled forcibly from one’s lungs during the first second of forced exhalation
- Forced Expiratory Flow or FEF: It is a calculation of the quantity of air that can be breathed out from the lungs and can be a definitive indicator of airway resistances.
- FEV1/FVC {FEV1 Percent or FEV1%}: The ratio of FEV1 to FVC allows the clinician to calculate the percentage of total quantity of air that is removed from one’s lungs at the time of the first second of forced exhalation.
- Peak Expiratory Flow Rate or PEFR: It evaluates the effect of treatment methods in the recovery of respiratory conditions such as COPD
- Maximal Voluntary Ventilation or MVV: This refers to a value that is calculated by asking the patient to exhale and inhale as quickly and completely as possible in twelve seconds. The stiffness of the muscles, the status of the respiratory muscles and the presence of airway obstructions can be gauged by the subsequent results. In case of poor results, the doctor will come to know that there are going to be respiratory complications post surgery.
