[Source: PLOS One, full page: (LINK). Abstract, edited.]
OPEN ACCESS / PEER-REVIEWED / RESEARCH ARTICLE
Veterans with Gulf War Illness exhibit distinct respiratory patterns during maximal cardiopulmonary exercise
Jacob B. Lindheimer , Dane B. Cook, Jacquelyn C. Klein-Adams, Wei Qian, Helene Z. Hill, Gudrun Lange, Duncan S. Ndirangu, Glenn R. Wylie, Michael J. Falvo
Published: November 12, 2019 / DOI: https://doi.org/10.1371/journal.pone.0224833
The components of minute ventilation, respiratory frequency and tidal volume, appear differentially regulated and thereby afford unique insight into the ventilatory response to exercise. However, respiratory frequency and tidal volume are infrequently reported, and have not previously been considered among military veterans with Gulf War Illness. Our purpose was to evaluate respiratory frequency and tidal volume in response to a maximal cardiopulmonary exercise test in individuals with and without Gulf War Illness.
Materials and methods
20 cases with Gulf War Illness and 14 controls participated in this study and performed maximal cardiopulmonary exercise test on a cycle ergometer. Ventilatory variables (minute ventilation, respiratory frequency and tidal volume) were obtained and normalized to peak exercise capacity. Using mixed-design analysis of variance models, with group and time as factors, we analyzed exercise ventilatory patterns for the entire sample and for 11 subjects from each group matched for race, age, sex, and height.
Despite similar minute ventilation (p = 0.57, η2p = 0.01), tidal volume was greater (p = 0.02, η2p = 0.16) and respiratory frequency was lower (p = 0.004, η2p = 0.24) in Veterans with Gulf War Illness than controls. The findings for respiratory frequency remained significant in the matched subgroup (p = 0.004, η2p = 0.35).
In our sample, veterans with Gulf War Illness adopt a unique exercise ventilatory pattern characterized by reduced respiratory frequency, despite similar ventilation relative to controls. Although the mechanism(s) by which this pattern is achieved remains unresolved, our findings suggest that the components of ventilation should be considered when evaluating clinical conditions with unexplained exertional symptoms.
Citation: Lindheimer JB, Cook DB, Klein-Adams JC, Qian W, Hill HZ, Lange G, et al. (2019) Veterans with Gulf War Illness exhibit distinct respiratory patterns during maximal cardiopulmonary exercise. PLoS ONE 14(11): e0224833. https://doi.org/10.1371/journal.pone.0224833
Editor: Kathryn L. Weston, Teesside University/Qatar Metabolic Institute, UNITED KINGDOM
Received: May 7, 2019; Accepted: October 22, 2019; Published: November 12, 2019
This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Data Availability: All data were collected at the VA and the signed subject consent forms did not make provision for making individual data records publicly available, even in de-identified form. However the authors can provide the “metadata” – i.e. the numerical (aggregated data) results used to generate the figures. Requests for access can be sent to: Sharmaine Forde-Miller Privacy Officer East Orange Campus of the VA New Jersey Healthcare System 385 Tremont Ave East Orange, NJ 07018 PH: 973-676-1000 x1948 Sharmaine.Forde-Miller@va.gov or Joselyn McLaughlin, PhD Research Compliance Officer Directors’s Office East Orange Campus of the VA New Jersey Healthcare System 385 Tremont Ave East Orange, NJ 07018 PH: 973-676-1000 x2035 Joselyn.McLaughlin@va.gov.
Funding: This work was supported by Department of Veterans Affairs Office of Research & Development; Clinical Science Research & Development: 1I21CX000797 (MJF), 1K2CX001679 (JBL), www.research.va.gov. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
Keywords: Gulf War Illness; Toxic chemicals; Undiagnosed illness; Soldiers; USA; Cardiology.