Cardiopulmonary exercise testing to assess respiratory impairment in occupational lung disease.

Exercise testing can answer several pertinent questions for the physician. It can determine whether a worker's aerobic performance is limited by respiratory or by other factors. It can also help decide whether an individual can perform a job without undue physiologic limitations and fatigue. Exercise testing has its limitations. It cannot determine the etiology of the impairment nor can it make a specific diagnosis except in rare cases. Interpretation of exercise data is not always precise, especially when the VO2max is normal but several physiologic measurements are abnormal. The VO2max achieved under laboratory conditions is probably too simplistic an estimate of the complex energy requirements of any occupation. Future research is needed to develop portable devices to assess both aerobic and anaerobic potentials of workers on the job to better determine job-specific impairment and disability. Patients who have unexplained symptoms or abnormal, but not severely reduced, static pulmonary function tests benefit most from exercise testing. For now, the AMA criteria for impairment as defined by static and exercise pulmonary function testing are the most appropriate to follow. Exercise testing has provided valuable data for epidemiologic research. Descriptive and case-control studies have documented minor physiologic abnormalities and rare respiratory limitations in workers with asbestos exposure and simple coal worker's pneumoconiosis. Additional studies are necessary to further elucidate pathophysiologic findings in patients with asbestosis and other occupationally induced pulmonary diseases.