What is the difference between COPD and Asthma?
A common concern of patients is the difference between chronic obstructive pulmonary disease (COPD) and asthma. Although a detailed comparison is beyond the scope of this article, one can consider basic differences between the two conditions. Both diseases are considered to be “obstructive” lung diseases, meaning that patients have difficulty exhaling completely between breaths. Obstructive lung diseases can be diagnosed by lung testing called spirometry. In this test, patients exhale forcibly into a machine which measures the amount of air they exhale in 1 second (Forced Expiratory Volume-1 or FEV1), and the total amount of air they exhale in a breath (Forced Vital Capacity or FVC). The machine then calculates a ratio of how much air was exhaled in the first second vs. the total amount of air exhaled in the breath, which is called the FEV1/FVC ratio. Said a different way, most patients will exhale 70% or more of their breath in the first second of exhalation. If they do not, they are considered to have a form of obstructive lung disease, such as asthma or COPD.
Do I have it?
Asthma typically, although not universally, presents at a younger age ( Chronic Obstructive Pulmonary Disease (COPD) typically presents later in life (over age 40), and is also associated with shortness of breath, coughing, wheezing, and chest tightness. COPD more commonly has additional symptoms of sputum production and shortness of breath requiring short term oxygen use. Like asthmatics, patients may feel increased symptoms when exposed to triggers such as fumes, or with lung infections. Also, like asthmatics, patients with COPD will have a reduction in their ability to exhale, and will show reductions in airflow when tested with spirometry. However, unlike asthmatic patients, COPD patients will not be able to completely correct their lung function even with treatment. COPD is also associated with permanent structural changes in lung structure, which may be seen on radiological studies such as CT scans. Emphysema is one such permanent change, and is a condition of destruction of alveoli, which are the parts of the lung where oxygen is absorbed into the blood stream. Emphysema is often seen in the setting of COPD, and is rarely seen with asthma. Tobacco use is by far the most common cause for COPD in developed countries, but other causes for COPD do occur such as genetic conditions. Alpha-1 antitrypsin deficiency (A1AT) is an example of a genetic condition which causes COPD in patients. This condition can be diagnosed with a simple blood test, and treatment is available to allow patients with A1AT to maintain their lung function.
Can it be treated?
Importantly, asthma and COPD can co-exist in patients, and it can be difficult to sort out whether patients have one or both conditions. Allergist/immunologists are experts in this area of medicine, and are commonly consulted to help with the diagnosis and treatment of these conditions. Allergists can rely on spirometry testing as discussed, or may order additional lung testing, such as full pulmonary function tests (PFTs). Fortunately, both asthma and COPD have great treatments to allow patients to breathe at their best. To learn more, consult your trusted Allergy Partners physician or visit allergypartners.com.
By Dr. Todd Cross
Allergy Partners of Western North Carolina