Cardiopulmonary Exercise Testing in the Study of Active Duty Military for Pulmonary Disease Related to Environmental...

Background: Chronic respiratory symptoms are reported after military deployment in support of combat operations. The spectrum of clinical lung diseases was initially defined by the Study of Active Duty Military for Pumonary Disease Related to Environmental Deployment Exposures (STAMPEDE) III. Does cardiopulmonary exercise testing (CPET) performed during this evaluation demonstrate differences based on established clinical diagnoses? Methods: Military personnel with chronic respiratory symptoms underwent a standardized evaluation as reported in the STAMPEDE III study. CPET was performed on a treadmill using a Bruce protocol, and all participants exercised to maximal exertion. Standard cardiac and respiratory CPET parameters were compared based on diagnosis, pulmonary function testing, and underlying comorbidities. Historical control patients included asymptomatic, nondeployed military personnel with normal imaging and spirometry who previously performed identical CPET testing. Results: In total, 356 participants from STAMPEDE III (38.3 ± 8.7 years) completed a single CPET study during the standardized evaluation. Values were compared with 108 nondeployed controls (28.8 ± 3.9 years). Participants versus controls demonstrated a significant reduction in exercise capacity based on time (10:09 ± 1:51 vs 12:58 ± 2:11, P < .001), metabolic equivalents (10.9 ± 1.7 vs 12.8 ± 1.7, P < .001), and V̇_O2 peak (mL/kg/min) (37.3 ± 7.1 vs 46.7 ± 6.9, P < .001). In the comparison of respiratory parameters, both minute ventilation/maximum voluntary ventilation (0.80 ± 0.18 vs 0.69 ± 0.15) and breathing reserve percentage (20.3 ± 17.5 vs 25.9 ± 13.1) identified significant differences (P < .05) driven by asthma and lower airway categories, whereas breathing frequency and tidal volume/inspiratory capacity were not different. Differences in exercise capacity were influenced by the presence of post-traumatic stress disorder/traumatic brain injury, mental health disorders, and body mass index >30 kg/m². Conclusions: The use of CPET for postdeployment pulmonary diagnoses showed a decrease in exercise capacity compared with normal controls. Although several ventilatory parameters were elevated in asthma and lower airway diseases, individuals diagnosed with only exertional dyspnea did not demonstrate changes. Propensity matching confirmed that CPET does not suggest undiagnosed respiratory disease during a normal postdeployment pulmonary evaluation.