Spirometry is the medical practice of testing one’s lungs for their ability to move air in and out of the body. Your doctor may refer to it by other names such as a pulmonary function test (PFT) or even more simply, a lung function test, but it is the practice of Spirometry as defined by the American Thoracic Society.
What Tests are Done in Spirometry?
The test is performed using a device called a spirometer. An individual breathes in and forcefully exhales into the spirometer through a mouthpiece. The specific measurements such as volume of air expelled and the pressure you were able to exert in forcing the air out of your lungs are compared to a table of typically healthy measurements as people of your race, age, gender, height, and weight.
What is a Spirometer and What Accessories are needed to Use it.
In technical terms, a spirometer is a precision differential pressure amplifier for taking measurements of respiratory flow rates. The information gathered by the Spirometer is fed directly into a computer running the spirometry extension software that then calculates flow, volume and forced expiratory measurements. There are two different technologies used to make spirometers.
- Volumetric Spirometers
- Flow Measuring Spirometers
Volumetric spirometers measure the volume of air that is inhaled or exhaled directly. These devices provide immediate measurements of the volume per unit time. The most common volumetric spirometers work with an accordion-like bellows that moves as the person breathes into a tube.
Flow spirometers measure the speed at which air flows into and out of the lungs. These devices are smaller than volume spirometers. As a person breathes into and out of the spirometer, a detector samples the air speed up to 300 times per second. The air speed is then converted to an equivalent volume of air passing in and out of the lungs. The detector may measure speed using a small turbine that spins or a heated wire.
Accessories for Use with Spirometers
- Adenoid Curette – a surgical device used by a qualified doctor to remove the adenoids in the event they are causing breathing difficulties or are infected.
- Mouthpieces – different types and sizes to prevent leaks and provide ergonomic comfort when breathing into the spirometer. There are also mouthpieces designed specifically for smokers and pediatric mouthpieces for children and adolescents.
- Filters – for the trapping and separation of bacteria and viruses. Volumetric spirometers are particularly susceptible to contamination, mold, and mildew from repeated use without being properly cleaned.
- Nose Clips – for sealing the nasal passage to insure an accurate reading of lung function.
- Calibration syringes for use with flow spirometers that need calibrated periodically.
- Computers to run the analysis software
- Software that interprets the sensor readings from the spirometer and provides a reading on the volume of air moved in and out of the lungs
- Thermal paper to print out graphs of lung function based on computer analysis
The flow spirometers are the ones you would most likely use at home for self-checking your ability to breathe properly. They are smaller and more lightweight but do require calibration more often. The volumetric spirometers provide real-time readings and immediate results but are used primarily at health care facilities, doctor’s offices, and hospitals.