Deployed Veterans exhibited reduced respiratory frequency (η2partial 0.26) and greater dyspnea (η2partial 0.18) during maximal exercise compared to non-deployed controls.
Case-Control (n=48)
Does deployment to Southwest Asia affect respiratory patterns and dyspnea during maximal cardiopulmonary exercise in Veterans?
Deployed Veterans to Southwest Asia exhibit altered respiratory patterns and greater dyspnea during maximal exercise, highlighting the utility of CPET in evaluating deployment-related dyspnea.
Effect estimate: η2partial 0.26
BACKGROUND: Exertional dyspnea and exercise intolerance are frequently endorsed in Veterans of post 9/11 conflicts in Southwest Asia (SWA). Studying the dynamic behavior of ventilation during exercise may provide mechanistic insight into these symptoms. Using maximal cardiopulmonary exercise testing (CPET) to experimentally induce exertional symptoms, we aimed to identify potential physiological differences between deployed Veterans and non-deployed controls. MATERIALS AND METHODS: Deployed (n = 31) and non-deployed (n = 17) participants performed a maximal effort CPET via the Bruce treadmill protocol. Indirect calorimetry and perceptual rating scales were used to measure rate of oxygen consumption (Formula: see text), rate of carbon dioxide production (Formula: see text), respiratory frequency (f R), tidal volume (VT), minute ventilation (Formula: see text), heart rate (HR), perceived exertion (RPE; 6-20 scale), and dyspnea (Borg Breathlessness Scale; 0-10 scale). A repeated measures analysis of variance (RM-ANOVA) model (2 groups: deployed vs non-deployed X 6 timepoints: 0%, 20%, 40%, 60%, 80%, and 100% Formula: see text) was conducted for participants meeting valid effort criteria (deployed = 25; non-deployed = 11). RESULTS: Significant group (η2partial = 0.26) and interaction (η2partial = 0.10) effects were observed such that deployed Veterans exhibited reduced f R and a greater change over time relative to non-deployed controls. There was also a significant group effect for dyspnea ratings (η2partial = 0.18) showing higher values in deployed participants. Exploratory correlational analyses revealed significant associations between dyspnea ratings and fR at 80% (R2 = 0.34) and 100% (R2 = 0.17) of Formula: see text, but only in deployed Veterans. CONCLUSION: Relative to non-deployed controls, Veterans deployed to SWA exhibited reduced fR and greater dyspnea during maximal exercise. Further, associations between these parameters occurred only in deployed Veterans. These findings support an association between SWA deployment and affected respiratory health, and also highlight the utility of CPET in the clinical evaluation of deployment-related dyspnea in Veterans.
Alexander et al. (Wed,) conducted a case-control in Exertional dyspnea and exercise intolerance (n=48). Deployment to Southwest Asia vs. Non-deployed controls was evaluated on Respiratory frequency (fR) and dyspnea ratings during maximal exercise (η2partial 0.26). Deployed Veterans exhibited reduced respiratory frequency (η2partial 0.26) and greater dyspnea (η2partial 0.18) during maximal exercise compared to non-deployed controls.
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