Asthma is classified as an obstructive lung disease. This means asthmatics have difficulty getting air out or exhaling. This is caused by narrowing of the airways and manifests as wheezing or prolonged exhalation. The ability to move air in and out can be measured by a simple test called spirometry. Spirometry is an integral part of the management of asthma. It is such an important test, that everyone with asthma should do it at least once and most asthmatics need it more often.
The reason this is so important is twofold. First, there is a huge disconnect between how people perceive their asthma severity and the reality of their lung function. I commonly see people whose self-reported symptoms are minimal but whose lung function is poor. This makes a big difference in what medications to use. Second, listening to the lungs with a stethoscope, called auscultation (aw-skull-TAY-shun), cannot tell you all you need to know. Even if the lungs are clear, testing may reveal diminished lung function.
An important part of spirometry that is underutilized is called bronchodilator reversal. What this means is, after measuring the lung function, the patient is given a “breathing treatment” with albuterol and then the lung function is measured again. A significant change in lung function, or lack thereof, is a very important clue as to how active a person’s asthma is.
If you have asthma, and especially if you take regular asthma medications, you need to have your lung function measured to ensure that you are doing all you need to do to keep your asthma under control.
Post-post mini rant: A huge pet peeve of mine is calling spirometry “Pulmonary Function Testing” (PFT). Spirometry is one component of PFT, with the others being measurement of lung volumes and measurement of how well gas moves between the lungs and the bloodstream, called DLCO. Full PFTs are important in the diagnosis and management of many lung diseases, but asthma is not one of them.