The Science Journal of the American Association for Respiratory Care

1997 OPEN FORUM Abstracts

Exercise: Normal and Abnormal Responses and How To Use Them

Robert B. Schoene, MD, Tuesday, December 9, 1997.

Many times resting pulmonary function tests do not give insight into a patient's underlying pathophysiology. Cardiopulmonary exercise testing often will provide important information which will guide further work-up into the patient's symptomatology. The primary reasons for exercise testing are: 1) dyspnea of unclear etiology; 2) disability evaluation; 3) chest pain of unclear etiology; 4) athleticism; and 5) pulmonary vascular disease. Accurate measurements require calibrated equipment, a skillful and knowledgeable technician, and a physician or physiologist who can interpret the data properly. The evaluator must decide whether a physiologic impairment can lead to performance disability.

The data cannot provide one single variable which will provide a discrete diagnosis, but pattern recognition of a number of variables require experience. Maximum oxygen consumption is the gold standard for determining a patient's or athlete's aerobic capacity. The data, however, can be further divided into ventilatory response which includes overall minute ventilation, ventilatory pattern (tidal volume and respiratory rate), ventilatory equipment (VE/VO2), and dead space ventilation. Ventilatory limitation can then be determined by the patient's resting spirometry and subsequent ventilatory response. Measurements of gas exchange (PaO2, SaO2, A-aDO2) are critical. The evaluation of cardiac response includes sub-maximal and maximal heart rate, oxygen pulse, and indirect measurement of stroke volume (VO2/heart rate), blood pressure and electrocardiogram are essential. The ventilatory anaerobic threshold provides information about a patient's or athlete's inherent response for fitness and it can be used as a marker for training.

These data can provide the clinician with direction for further work-up which may lead to discrete diagnosis for a patient's symptomatology or specific guidelines on an athlete's training schedule.

AARC 50th Anniversary, December 6 - 9, 1997, New Orleans, Louisiana.

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