ABSTRACT
The diagnosis of chronic obstructive pulmonary disease (COPD) is often included in the request for a diagnostic CPET, but the COPD is ordinarily a relatively minor impairment in this setting. However, for even mild or moderate COPD, the rapid respiratory rate of heavy exercise can lead to a variable extent of air trapping not reliably predicted from the measurement of the FEV1. Measurement of the exercise inspiratory capacity during a CPET will provide insight into that dynamic hyperinflation and identify when milder degrees of airflow obstruction contribute to overall exercise impairment. For patients with severe COPD, exercise is limited by maximal ventilation capacity, with associated acute respiratory acidosis during a maximal sustained effort. The hallmarks of an obstructive limitation to maximal exercise include maximal exercise ventilation reaching 35 times the resting FEV1 and a failure to decrease the end-tidal PCO2 with maximal exercise effort. Exercise-induced bronchospasm is best diagnosed by breathing dry air while undergoing sustained heavy treadmill exercise, followed by a timed sequence of spirometry measurements. Variable upper airway dysfunction during exercise is best diagnosed by fiberoptic laryngoscopy during exercise.
