Lung function tests are commonly advised in patients with chronic lung diseases such as emphysema, bronchitis, pulmonary fibrosis, and chronic obstructive pulmonary disease. Multiple lung function tests help the doctor assess different lung functions such as lung size, the airflow, and the rate of diffusion of gases in your lungs. These tests involve the use of a lung function machine and are very important in determining one’s respiratory health.
Device to Measure Lung Capacity
Respiratory diseases are on the rise due to a variety of internal as well as environmental factors. Due to this reason, the importance of devices such as the spirometer has increased. A spirometry test is quick, painless and can obtain very valuable information about respiratory functions. Therefore, a spirometer is a very commonly used lung function machine to measure lung capacity.
How to Measure Lung Capacity
There are multiple lung function tests, and some of the most widely used tests that are instrumental in assessing lung function are listed below:
1. Spirometry Tests
To use a spirometer on your patients, the patient is required to breathe into a tube, which is attached to the lung function machine. This device helps in measuring the airflow along with the volume of air you inhale and exhale. The test helps in determining the Forced Vital Capacity (FVC) of your lungs. The patient is asked to take a deep breath and then exhale into the machine as hard as possible for as long as possible. The FVC refers to the total amount of air you can breathe out after inhaling the maximum amount of air (according to your capacity). Spirometry test results can also help with several other assessments. These include:
- Forced Expiratory Volume 1 (FEV1) – the volume of air exhaled in 1 second.
- Minute Volume (MV) – the volume of air exhaled in one minute.
- Tidal Volume (VT) – the volume of air inhaled or exhaled during normal breathing.
- FEV1/FVC ratio – This is the ratio of FEV1 to FVC.
- Total lung capacity (TLC) – TLC is the maximum volume of air present in the lungs.
2. Gas Diffusion Tests
The most common types of gas diffusion tests include the arterial blood gas test and the carbon monoxide diffusion capacity test. Gas diffusion tests help the doctor find out the number of gases that diffuse or pass through the alveoli of the lungs.
3. Body Plethysmography Tests
These tests help in measuring one’s Total lung capacity (TLC) and the Residual volume (RV). The TLC refers to the total amount that your lungs can hold while RV refers to the amount of air that would remain in your lungs even after forced exhalation.
4. Exercise Tolerance Tests
People with respiratory and lung diseases tend to experience symptoms like breathlessness and pain in the chest, especially while doing any exercise. Exercise tolerance tests help the doctor determine one’s exercise capacity.
5. Pulse Oximetry Tests
A pulse oximetry test is a simple and painless test where a finger-clip like a device is placed over the patient’s finger or on the earlobe and the device measures the amount of oxygen in the patient’s blood.
Lung Function Machine Results
The forced vital capacity and forced expiratory volume are often enough to get a basic idea about one’s respiratory health. If both these values fall within the normal range, then there is nothing to worry about.