The Centers for Disease Control and Prevention reports that the number one cause of death in the United States is heart disease. Additionally, chronic lower respiratory diseases, such as chronic obstructive pulmonary disease (COPD), are the third-leading cause of death in the nation. A cardiopulmonary exercise test (CPET) can help detect a variety of heart, lung and metabolic conditions and their severity.
The CPET, also known as a cardiopulmonary stress test (CPX), is a non-invasive, metabolic stress test that evaluates the function of the heart and lungs while at rest and during exercise. The heart and lungs work as a team to provide oxygen to different muscles, creating energy and producing carbon dioxide. Diseases such as COPD and heart disease restrict how fast this system can work.
The CPET examines the heart, lungs and muscles and how well they are working independently and together as a system. The cardiopulmonary system is assessed by measuring how much oxygen the body uses, the amount of carbon dioxide the body is producing, breathing patterns and electrocardiogram (EKG), which detects the heart’s electrical activity.
This stress test is different than a traditional stress test. Traditional treadmill stress tests only examine the EKG, which solely focuses on the heart. The CPET is the only test that can detect conditions affecting the heart, lungs and body’s metabolism that can cause shortness of breath, intolerance to exercise and physical activity, and pain and discomfort in the chest.
Different conditions can be monitored by the CPET including heart failure, muscle metabolic disorders, COPD, pulmonary circulation and ventilation disorder, and chronotropic incompetence. The CPET can be used on patients already experiencing these conditions to monitor how well they’re responding to treatment.
The CPET can be performed walking on a treadmill or riding a stationary bicycle. The patient wears a face mask, which monitors the usage of oxygen, production of carbon dioxide and breathing pattern. In addition, the patient wears a cuff on the arm throughout the test to monitor blood pressure, and electrocardiography stickers are applied to the chest to observe the patient’s heart rate.
Breathing tests are performed before pedaling or walking to evaluate function at rest. Test results are later compared with the breathing that occurs during exercise. The test begins with low-speed warmup, and the speed and effort gradually increases to mimic walking or pedaling uphill. The patient is encouraged to exercise for as long as he or she can to capture heart and breathing information at maximum exercise ability.
A cardiopulmonary stress test may be needed if you are experiencing unexplained shortness of breath, to determine the severity of congestive heart failure or to develop a safe exercise program. Speak with a health care professional about whether the CPET could provide insight to your health concerns.
Michael Schaeffer, MD, is with KentuckyOne Health Cardiology Associates.