COMMENTARY

If You're Serious About Treating Dyspnea, You'll Need a Cardiopulmonary Exercise Test

Aaron B. Holley, MD

Disclosures

May 19, 2017

An 80-year-old woman with mild chronic obstructive pulmonary disease (COPD) is referred to the pulmonologist for dyspnea. She is obese and sedentary; an echocardiogram shows grade I diastolic dysfunction (DDfxn), and forced vital capacity and FEV1 are mildly reduced. The referring provider wants to know whether this woman would benefit from an inhaler. The patient wants to feel better during activities of daily living. She would also like to walk outdoors and at the mall.

From the history, one can easily glean the contributors to her dyspnea: COPD,[1] DDfxn,[2] obesity,[3] and deconditioning.[4] Being the reductionist physician that you are, and having very little time, you prescribe tiotropium and hope for the best. You refer the patient back to her primary care provider (PCP). The PCP checks the box: "Patient has been evaluated by pulmonary." But the patient's dyspnea does not improve. No need to go back to pulmonary, but perhaps referral to cardiology?

Why Not CPET?

As an alternative, why not order cardiopulmonary exercise testing (CPET)? I do not know how many pulmonologists are comfortable with CPET, but my sense from clinical practice and academic conferences is, not many. I have had too many experienced, intelligent physicians tell me CPETs are not helpful. After all, what can they tell us that we do not already know? In my opinion, quite a bit.

CPET provides a comprehensive assessment of the physiologic response to exercise.[5] Is our 80-year-old limited by mild COPD or DDfxn during activities of daily living, or is it all deconditioning? The PCP can start inhalers or prescribe furosemide, but as the dyspnea expert, the pulmonologist can (and should) do more. At bare minimum, the CPET always provides data for writing an exercise prescription.[6] In addition, it is your best chance to quantify the cardiopulmonary and skeletal muscle contributions to activity limitation.[4,5,7]

The detractors say that we do not have good reference values, and that too often normal ranges overlap with findings in disease. Their points are well taken, but their focus is wrong. CPET need not be used for defining normal vs abnormal. Rather, CPET is used to identify the physiologic causes of activity limitation.

The data are there. Reference values for active,[8,9] sedentary,[10] and military service members[11,12] exist. Guidelines for interpretation are published in pulmonary,[13] cardiology[2,14] and medicine[4,7] journals. In the past few months, the journals CHEST[15] and the Annals of the American Thoracic Society [16,17,18] have published articles about CPET.

Do not fear the test. Embrace it, and be a real pulmonologist for your patients.

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