Obesity is Associated With an Increased Respiratory Workload During Exercise

Abstract

SESSION TITLE: Pulmonary Physiology SESSION TYPE: Original Investigation Poster PRESENTED ON: Wednesday, November 1, 2017 at 01:30 PM - 02:30 PM PURPOSE: Prior literature supports a relationship between obesity and respiratory workload. Among younger, active duty military patients with respiratory symptoms, we sought to quantify the effect that obesity has on respiratory workload during cardiopulmonary exercise testing (CPET). METHODS: The STAMPEDE Study enrolls enrolls active duty service members with respiratory symptoms following deployment to Iraq or Afghanistan. All subjects undergo a comprehensive, standardized pulmonary evaluation. During treadmill CPET, minute ventilation (VE), proportion of maximum voluntary ventilation (VE/MVV), and the ventilatory equivalents for O2 (VE/VO2) and CO2 (VE/VCO2) were measured at rest, a pre-specificed, sub-maximal VO2 of 25mL/kg/min and at max exercise. Subjects with obesity (BMI > 30 kg/m2) were compared to those without using the student t-test. We modeled obesity against other predictors of respiratory workload using linear regression. Data were analyzed using STATA (version 12). RESULTS: A total to 301 participants had data available for analysis. Patients with obesity were older, and more likely to be female, depressed and positive for serum nicotine. FVC % predicted (PPD) was lower (95.1 vs 90.2%; p=0.01) and R5 (129.8 vs 157.2%; p<0.001) and R20 (127.1 vs 136.2%; p=0.045) PPD were higher in patients with obesity. Patients with obesity had higher VE and VE/MVV at rest, higher RR, TV, VE and VE/MVV at submaximal exercise, and no differences in respiratory workload but significantly lower VO2 (cc/kg/min) at max exercise. At submaximal exercise, obesity was significantly related to VE/MVV (p<0.001) after controlling for significant differences at baseline. CONCLUSIONS: In a cohort of active duty service members with respiratory symptoms following deployment, obesity was independently associated with an elevated respiratory response to submaximal exercise. The obese do more respiratory work to achieve a given VO2 (ml/kg/min). CLINICAL IMPLICATIONS: BMI is independently associated with respiratory workload among service members presenting with unexplained dyspnea. DISCLOSURE: The following authors have nothing to disclose: Michael McMahon, Aaron Holley, Jacob Collen, Andrew Skabelund, Jeffrey Woods, John Sherner, Michael Morris No Product/Research Disclosure Information