Cardiopulmonary stress testing. A review of noninvasive approaches.

With readily available techniques, cardiopulmonary exercise testing permits noninvasive measurement of such parameters as heart rate, cardiac output, oxygen saturation, ventilation, and gas exchange to bring out abnormalities which are either underestimated or not detectable at rest. These parameters may be used to characterize a patient's primary limitation of exercise tolerance as either cardiac or pulmonary in origin. They can also provide precise data to assess response to treatment. Pulmonary gas exchange is evaluated primarily by measurement of oxygen consumption, carbon dioxide production, and ventilation over time. The relationship of these parameters to one another changes throughout the course of incremental exercise testing. By appreciating these basic relationships, the more complex abnormalities found in disease states can be understood.