Spirometers are a medical device used to measure respiration flow rates in the lungs. They record the amount of air breathed in and out over a specific period of time and are used to test the condition of a patient's lungs. Diseases such as emphysema, bronchitis, and asthma can be tested for with this device. It is often used to find out the cause of shortness of breathe, to assess lung function due to contaminants, the effects of medications, and the progression of disease.

The test involves some fast and forced periods of breathing and can cause a temporary shortness of breath or a feeling of lightheadedness. The patient wears nose clips and breathes through a tight fitting mouthpiece. Normal results are based on height, ethnicity, sex, and age. A value less than 80 percent is considered abnormal. Ranges can vary slightly among laboratories.

When the result is abnormal it can be an indication of a chest or lung disease such as chronic bronchitis, emphysema, asthma, or an infection. In these cases the lungs hold too much air and can take a longer time to empty. These conditions are known as obstructive lung disorders and can sometimes cause scarring and produce a smaller lung capacity so that the lungs don't hold enough air and do not transfer oxygen into the blood effectively. Some illness that are contributors to these diseases are fibrosis of the lungs, being extremely overweight, lung cancer, and scleroderma and sarcoidosis.

For most, this test poses very little risk, but there are conditions that could cause the risk of a collapsed lung such as those who have certain lung diseases. People who have heart disease or have recently experienced a heart attack should avoid this test.

Cooperation is of the utmost importance when taking this test for the best results. The mouthpiece seal must be tight or the results will be bad and difficult to interpret. Smoking is not advised for at least 4 to 6 hours beforehand and do not eat a heavy meal prior to testing. People who use inhaler medications or a bronchodilator will get special instructions.

Another way to measure lung volume is by breathing helium or nitrogen gas through a tube for a specified amount of time. One can also have a diffusion capacity measurement done by breathing a tracer gas that is harmless for a short amount of time for one breath. The gas is measured as one breathes out and the difference between the gas breathed in and exhaled is measured. This type of testing checks for oxygen movement from the air into the bloodstream.

This test is a routine part of a physical and can alert the physician to possible problems with lung function for early detection and treatment. It is non-invasion and of minimal discomfort to the patient while being performed. It takes but a few minutes to get an accurate assessment of how the lungs are functioning.

With the invention of spirometers as far back as 129 A. D. By a physician in Greece using an animal bladder to our current version invented in 1974, this medical device has proven to be an accurate measurement of lung volume to assist in the detection and monitoring of diseases and the effect of medications.