What is cardiopulmonary exercise testing (CPET)?

Updated: Nov 21, 2018
  • Author: David Akinpelu, MD, FACP; Chief Editor: Eric H Yang, MD  more...
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CPET is a useful adjunctive tool for the assessment of patients with cardiovascular and pulmonary disease. It involves measurements of gas exchange, primarily oxygen uptake (ie, VO2), carbon dioxide output (VCO2), minute ventilation, and anaerobic (lactic acid) threshold. Patients usually wear a nose clip and breathe through a nonrebreathing valve that separates expired air from room air.

VO2 at maximal exercise (peak VO2) is considered the best index of aerobic capacity and cardiorespiratory function. Estimation of maximal aerobic capacity by using published formulas based on exercise time or work rate without direct measurement is limited by physiologic and methodologic inaccuracies.

According to data acquired from patients with heart failure who have undergone cardiopulmonary stress testing with this method, subsequent analysis is reliable and important and has been shown to benefit this subgroup of patients the most.

Such data are only partly influenced by resting left ventricular dysfunction. Maximal exercise capacity does not necessarily reflect the daily activities of patients with heart failure. Use of this technique to stratify patients with ambulatory heart failure has improved the clinician’s ability to identify those with the poorest prognosis, who should be considered for heart transplantation.

Abnormal ventilatory and chronotropic responses to exercise are also predictors of outcome in patients with heart failure. [24] In addition, evaluation of the rate of VO2 decline during exercise recovery (VO2 kinetics) may provide additional information regarding the functional state in patients with heart failure. Compared with normal oxygen kinetics, prolonged recovery time of VO2 has been correlated with poorer exercise tolerance, lower peak VO2, and a lower cardiac index.

Most investigators conclude that measurement of peak VO2 yields the best prognostic information in patients with heart failure. Evaluation of submaximal and recovery ventilatory responses may be particularly useful when exercise to near-maximal levels (respiratory exchange ratio greater than 1) is not achieved.

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