What is Cardiopulmonary Exercise Test (CPET)?
About the Data
CPET measures the amount of oxygen your body is using, the amount of carbon dioxide it is producing, your breathing pattern, and electrocardiogram (EKG) while you are riding a stationary bicycle.
This data undergoes expert analysis in the data center where exercise capacity is quantified using MET-TEST powerful proprietary pattern recognition software, and the mechanism of patient symptoms is prioritized.
This is a much more detailed level of insight and feedback to the ordering physicians than a traditional treadmill stress test. Besides detecting problems in the heart and lungs, serial testing with CPET is also used to monitor changes in your disease condition and response to therapeutic interventions such as exercise and medical therapy to ensure long-term health is headed in the right direction.
What conditions can be detected and monitored by CPET and non-traditional treadmill stress test??
The conventional treadmill stress test primarily identifies ischemic heart disease affecting larger blood vessels, albeit with limited accuracy. In contrast, a CPET surpasses the accuracy of this test in detecting ischemic heart disease while also capable of identifying numerous other conditions that the treadmill stress test might overlook.
Conditions affecting the heart, lungs, and metabolism often manifest as symptoms like shortness of breath, chest pain, fatigue, and exercise intolerance.
Coronary artery disease, heart failure and valve disease will impair ability to increase cardiac output with exertion and hence cause symptoms. CPET is frequently abnormal when routing cardiac testing in the cardiologist’s office is normal.
Muscle Metabolic Disorders
Inability of the muscle cells to use oxygen from the bloodstream to produce energy for the working muscle tissues (example: mitochondria disorders, McArdle’s disease, enzyme deficiency).
Inability to increase heart rate appropriately during exertion.
Poor cardiovascular fitness that can be improved with exercise.
Poor effort is easily detectable with appropriate interpretation on CPET.
CPET uniquely offers the ability to concurrently pinpoint the underlying system responsible for these issues.
Will I get the same results from CPET as I would with Treadmill or Nuclear Stress Test?
Nuclear stress testing, on the other hand, employs a radioactive substance injected into the bloodstream to estimate blood flow around the heart. Special cameras capture images before and after exercise to identify abnormalities, primarily in the major, large (macrovascular) coronary vessels. Nevertheless, it does not reveal any issues in the smaller (microvascular) blood vessels within the heart. Additionally, nuclear stress testing may miss cases where there are blockages in multiple vessels or in vessels not easily visualized due to their location.
In contrast, CPET does not rely on imaging but instead conducts a physiological assessment. It gauges the performance of your heart, lungs, and muscles during exercise, considering various physiological variables that might restrict your exercise capacity. Importantly, no other test offers the capability to concurrently measure heart, lung, and muscle function.
How is a CPET performed?
Unlike a traditional stress test, the CPET is performed on a stationary bicycle, which is safer than a treadmill. Many patients feel more comfortable riding the bicycle than walking on a treadmill as they are seated and can stop when needed. The following equipment will be worn during the test:
Face Mask: This monitors the oxygen used, carbon dioxide produced, and the breathing pattern. The mask is placed over the mouth and nose. It does not restrict breathing and you will only be breathing in air from the environment.
Electrocardiogram (EKG): Ten stickers will be placed on your chest with monitoring wires attached. This is used to monitor your heart rate and rhythm.
Blood Pressure Cuff: Your blood pressure will be taken multiple times during the test. The cuff wraps around the upper part of your arm and tightens to measure your blood pressure.
Before exercise begins, you will be asked to perform two lung tests. The results of these tests will be compared to your breathing during exercise. Your technician will then fit the required equipment to you and help you get on the bicycle. While you are resting on the bicycle, your technician will explain the testing procedure in greater detail.
At the end of the rest period, you will be asked to begin pedaling lightly for a few minutes, to warm up. The resistance on the bicycle will then slowly become harder and harder as if you were going up a hill that keeps gently getting steeper and steeper. The test will continue until you are giving your maximum effort and can no longer continue.
To get the most accurate results for your doctor, it is important that you give your best effort for as long as you possibly can. If you do not give a maximum effort, your test may be “indeterminate” and your doctor will not have the most accurate information to help you. The exercise work load will be adjusted on an individual basis to enable each person give his or her best effort. Your technician will keep encouraging you to continue to get your best effort until he or she sees that you cannot continue. However, if your technician notices that you are experiencing certain symptoms the test will be immediately stopped. After the test is over, your technician will ask you to pedal slowly and gently to cool down while he or she continues monitoring your vital signs.
The actual time it takes to perform the test, from the time you get on the bike, through the exercise portion and recovery will be between 15 and 25 minutes. However, you will only be asked to exercise at a hard intensity for about 3 to 4 minutes.
For best results:
- Give your best effort and exercise for as long and hard as possible
- Keep your legs moving at the same speed for the entire test, even when it is difficult
- Avoid speaking during the test unless you have discomfort or pain
- Let the technician know if you have discomfort or pain at any point during the test
How often should I have a CPET?
The goal in every person is to increase Peak VO2 from baseline by 10% or more per test until the underlying cardiac dysfunction pattern is completely normalized.