Called cardiopulmonary exercise testing, or metabolic cart, it allows doctors to place patients on a treadmill or bike to assess a number of subtle functions, said Dr. Mehrdad Behnia, a pulmonologist and intensivist.
“I use it a lot in my patients who present with shortness of breath, when I cannot decipher what is going on,” he said. “It’s been very, very helpful to find out, physiologically, what is wrong with their lungs or other parts of their body.”
Behnia has begun assessing members of the Augusta Rowing Club to do measurements at the top of the scale, and he brought in as a consultant Dr. Bruce Johnson, a physiologist at the Mayo Clinic in Rochester, Minn., who has been doing the testing since the early 1980s.
For athletes, “this test can give you aerobic capacity,” Johnson said. “It can help you define your training intensities. It can tell you about your oxygen kinetics, how quickly you’re adapting to changes in workload. It will tell you about breathing efficiency. We know that it takes a certain amount of breathing to get rid of a liter of carbon dioxide. We can compare how efficient you are.”
That breathing efficiency, for instance, can play into endurance.
“While most of us will have relatively similar values, the more efficient you are, the lower your oxygen consumption is,” Johnson said. “That’s one of the things they said about Lance Armstrong. As he got older, he didn’t get more fit but he got more efficient. He was able to do more work with less oxygen consumption.”
The testing is valuable for Behnia when he is faced with a patient who is short of breath.
“I run into this problem so many times on a daily basis,” he said. The patient might have heart disease or lung disease or neither, and it is not obvious what the problem is.
“Then you scratch your head. What on Earth is going on?” Behnia said. “When you put them on a bike (for exercise testing), then you can get a lot of information that will really, really help you.”
Many times the differences between conditions are subtle and the testing can help tease them out, Johnson said.
“For certain diseases, it is highly predictive, like heart failure, like pulmonary hypertension, COPD (chronic obstructive pulmonary disease),” Johnson said. “They all have different and slightly characteristic patterns of how they respond on a test like this.”
The heart and lungs are closely linked in the body; insights into cardiovascular disease can also be gained, Johnson said.
“Anything that is going to happen in the lungs is eventually going to affect the heart, and vice versa,” he said. “I look at this kind of test as a simple test that gives you a window into what is going on with the heart as well. This test sometimes helps guide additional tests or is used in concert with other measurements to help better define treatment options.”