Effects of Deployment Exposures on Cardiopulmonary and Autonomic Function

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DESCRIPTION (provided by applicant): Project Summary/Abstract: Evidence is clear that Veterans deployed to Operations Enduring and Iraqi Freedom and Operation New Dawn (OEF/OIF/OND) have been exposed to high levels of particulate matter (PM) that exceeded environmental, occupational and military exposure guidelines. PM exposure is acknowledged as a risk factor for cardiovascular morbidity and mortality, and can increase the risk of and exacerbate airway disease. The reviewed epidemiology indicates a high prevalence of newly reported respiratory symptoms in OEF/OIF/OND Veterans that has significantly affected their deployment duties, including their physical exertion capability. Despite these retrospective data and limited air sampling reports, prospective studies are absent. Our pilot study will take an integrative approach to evaluate cardiorespiratory and autonomic function in OEF/OIF/OND Veterans as compared to Veterans never deployed to the region. To evaluate cardiopulmonary function, each Veteran will undergo an exercise challenge which consists of spirometry before and then serially after exercise (5, 10, 15, 20, and 30 min post-exercise). Exercise will be treadmill-based and participants will try to maintain 6 - 8 minutes of exercise at a target ventilation and heart rate. For spirometric testing, Veterans will be asked to perform a maximal forced expiratory maneuver at each time point. Spirometry will also be repeated on separate day to include the same maximal forced expiratory maneuver, but will be assessed before and after a bronchodilator. As we anticipate altered sympathovagal balance, we will evaluate several indices of heart rate variability during paced breathing. In addition, we will quantify cerebral blood flow, blood pressure, heart rate and ventilation in response to a Valsalva maneuver and postural change (i.e. sit-to-stand). This integrative assessment will provide an indication of how well the autonomic system regulates cardiovascular function, which is dependent on precise reflex regulation. These assessments may provide insight on the pathophysiological mechanisms that underlie endorsed symptoms, and may provide intervention points for attenuating long-term adverse outcomes such as pulmonary and cardiovascular disease. Data derived from this pilot project will yield important insight on the extent and severity of cardiorespiratory impairment - data that may then be used to guide rehabilitation. In addition, results from autonomic testing will be of similar efficacy in detecting the presence of subclinical or overt physiological changes. Through early identification, treatment options (e.g. exercise therapy, pharmaceutical) may be implemented to enhance autonomic function, with the goal of helping to alleviate symptoms and reduce chronic disease risk. PUBLIC HEALTH RELEVANCE: Project Narrative: Following deployment to Operations Enduring and Iraqi Freedom and Operation New Dawn (OEF/OIF/OND), Veterans report breathing problems, difficulty exercising and other symptoms. These symptoms are likely related to deployment exposures, such as regional dust and sand, smoke from burning trash, and local industry. Studies have reported poor air quality, but very little is known about the effect that exposure to this polluted air may have on Veterans' short- and long-term health. We will determine whether deployment-related exposures have affected respiratory and nervous system function in these Veterans - data that may then be used to guide rehabilitation. Ultimately, our long-term goal is early identification and evidence-based therapy to prevent the development of chronic respiratory conditions in this group of OEF/OIF/OND Veterans.