Cardiopulmonary Services at Doctors Hospital has added Complex cardiopulmonary exercise testing (CPET) to its menu of available diagnostic services. CPET is, as it sounds, the analysis of both cardiac and pulmonary data during exercise. The combination of this data with respiratory gas analysis makes CPET useful in a wide array of clinical applications from investigating and understanding the reason for unexplained shortness of breath to diagnosing asthma induced limitations in athletes.
How does CPET work?
CPET is used to define each organ system’s contribution to a patient’s symptoms of exertional dyspnea and exercise intolerance and also its extent of contribution—unlike the six-minute walk test, which is a simple test that measures the maximal distance that patients can walk at their own pace in 6 minutes.
According to Dr. Mehrdad M. Behnia, Medical Director of the Pulmonary Function Laboratory at Doctors Hospital, “There are numerous patients that are referred to me for evaluation of unexplained shortness of breath with a non-revealing medical workup. CPET gives me more information to find out the cause. Using this tool, I get specific information on which organ system in the body is most limiting to the breathing and exercise capacity which in turn helps us determine what the best treatment regimen will be to improve the condition. Not every patient with shortness of breath has heart or lung disease. Some may be just deconditioned or out of shape.” CPET can also assess patient’s effort level and is helpful in assessing if the prescribed treatment or exercise regimen has been effective or not.
Exercise is a Beautiful Thing
In order to fully comprehend the benefits of CPET, one must understand the beauty of the organ systems which work cooperatively when we exercise. Exercise requires the precise coordination of multiple body systems—cardiac, pulmonary, hematologic, and musculoskeletal. When the body first begins to exercise, it is powered by adenosine triphosphate (ATP) obtained from the creatine phosphokinase reserves in skeletal muscle. In order for exercise to be sustained, however, oxygen delivery to working muscle must occur. Initially, ventilation remains constant while cardiac stroke volume increases, followed by a progressive increase in heart rate as the demand for increased cardiac output continues. When the cardiovascular and pulmonary systems work together to increase oxygen delivery as the body increases exercise intensity, an individual can continue at a relatively comfortable level (with a brief recovery period afterward), limited only by the amount of fuel in the muscle. But when one of the organ systems falters, the others cannot compensate for a prolonged period.
Every Breath You Take
CPET is a computerized test that provides a breath-by-breath analysis of respiratory gas exchange and cardiac function at rest and during a period of exercise in which a patient utilizes bicycle ergometer. Information on airflow, O2 consumption, CO2 production, heart rate, and arterial blood gas are collected and used for computation of other variables. The test is also more sensitive for detecting early or subclinical disease than tests that are done at rest since resting pulmonary and cardiac function testing cannot reliably predict exercise performance and functional capacity. In addition, resting measurements do not correlate with overall health status like how exercise tolerance does.
The test could ultimately be complemented with echocardiography and could become very helpful for both cardiologists and pulmonologists in assessment of cardiorespiratory system when the two organs work synchronously.
Indications for CPET can include:
- Evaluation of cause of explained shortness of breath.
- Objective assessment of exercise capacity for disability evaluation-subject cannot malinger.
- Preoperative cardiopulmonary assessment.
- Evaluation of exercise induced asthma.
- Determination of whether dyspnea symptoms arise more from cardiac or pulmonary systems in patients who have disorders of both organ systems.
- Evaluation of candidates for heart and lung transplantation..
- Assessment of prognosis in selected disorders (eg, heart disease, pulmonary vascular disorders, and cystic fibrosis).
- Risk stratification in various heart and lung conditions such as congestive heart failure and pulmonary hypertension.
- Exercise evaluation and the prescription of pulmonary rehabilitation.
Find Out More
Cardiopulmonary Services at Doctors Hospital provides a wide array of pulmonary function testing, including simple spirometry, lung volumes, maximal voluntary ventilation studies, pre and post bronchodilator testing, the use of Methachloline to study airway resistance and reactivity and full body plethysmography. For more information on testing or to make a referral to a pulmonary specialist at Doctors Hospital, call (706) 651-4343.
The Pulmonary Laboratory is registered with the American Thoracic Society and is managed by a board certified pulmonary function technologist.