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Incidence, risk factors, and mortality associated with acute respiratory distress syndrome in combat casualty care

Park, Pauline K. MD; Cannon, Jeremy W. MD, SM; Ye, Wen PhD; Blackbourne, Lorne H. MD; Holcomb, John B. MD; Beninati, William MD; Napolitano, Lena M. MD

Journal of Trauma and Acute Care Surgery: November 2016 - Volume 81 - Issue 5 - p S150–S156
doi: 10.1097/TA.0000000000001183
Trauma Critical Care

BACKGROUND The overall incidence and mortality of acute respiratory distress syndrome (ARDS) in civilian trauma settings have decreased over the past four decades; however, the epidemiology and impact of ARDS on modern combat casualty care are unknown. We sought to determine the incidence, risk factors, resource utilization, and mortality associated with ARDS in current combat casualty care.

METHODS This was a retrospective review of mechanically ventilated US combat casualties within the Department of Defense Trauma Registry (formerly the Joint Theater Trauma Registry) during Operation Iraqi Freedom/Enduring Freedom (October 2001 to August 2008) for ARDS development, resource utilization, and mortality.

RESULTS Of 18,329 US Department of Defense Trauma Registry encounters, 4,679 (25.5%) required mechanical ventilation; ARDS was identified in 156 encounters (3.3%). On multivariate logistic regression, ARDS was independently associated with female sex (odds ratio [OR], 2.62; 95% confidence interval [CI], 1.21–5.71; p = 0.02), higher military-specific Injury Severity Score (Mil ISS) (OR, 4.18; 95% CI, 2.61–6.71; p < 0.001 for Mil ISS ≥25 vs. <15), hypotension (admission systolic blood pressure <90 vs. ≥90 mm Hg; OR, 1.76; 95% CI, 1.07–2.88; p = 0.03), and tachycardia (admission heart rate ≥90 vs. <90 beats per minute; OR, 1.53; 95% CI, 1.06–2.22; p = 0.02). Explosion injury was not associated with increased risk of ARDS. Critical care resource utilization was significantly higher in ARDS patients as was all-cause hospital mortality (ARDS vs. no ARDS, 12.8% vs. 5.9%; p = 0.002). After adjustment for age, sex, injury severity, injury mechanism, Mil ISS, hypotension, tachycardia, and admission Glasgow Coma Scale score, ARDS remained an independent risk factor for death (OR, 1.99; 95% CI, 1.12–3.52; p = 0.02).

CONCLUSIONS In this large cohort of modern combat casualties, ARDS risk factors included female sex, higher injury severity, hypotension, and tachycardia, but not explosion injury. Patients with ARDS also required more medical resources and were at greater risk of death compared with patients without ARDS. Thus, ARDS remains a significant complication in current combat casualty care.

LEVEL OF EVIDENCE Prognostic/epidemiologic study, level III.

Supplemental digital content is available in the text.

From the Division of Acute Care Surgery, Dept of Surgery, University of Michigan, Ann Arbor, Michigan (P.K.P., L.M.N.); School of Public Health, University of Michigan, Ann Arbor, Michigan (W.Y.); US Army Institute of Surgical Research, Fort Sam Houston, Texas (L.H.B., J.B.H.); Pulmonary/Critical Care Medicine, Wilford Hall Medical Center, Lackland AFB, Texas (W.B.); and Department of Surgery, Wilford Hall Medical Center, Lackland AFB, Texas and Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, Maryland (J.W.C.).

Submitted: March 20, 2016, Revised: April 29, 2016, Accepted: May 9, 2016, Published online: August 2, 2016.

J.W.C. is now with the Division of Traumatology, Surgical Critical Care & Emergency Surgery, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania. L.H.B. is now with the Department of Surgery, San Antonio Military Medical Center, Fort Sam Houston, Texas. J.B.H. is now with the Division of Trauma and Acute Care Surgery, University of Texas at Houston, Houston, Texas. W.B. is now with the Intermountain Healthcare, Salt Lake City, Utah.

P.K.P. and J.W.C. contributed equally to this study.

This study was supported by the US Air Force Office of the Surgeon General, Medical Modernization Branch, under contract FA7014-07-C-A010, Log 99, BAA 07-01 (principal investigator: L.M.N.). The funding organization discussed the study design with the investigators at the outset of the project; however, it had no role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation or review of the manuscript. The manuscript was reviewed for operational security and public affairs compliance according to the Department of Defense policy.

Presented in part at the American Association for the Surgery of Trauma 68th Annual Meeting, October 1–3, 2009, Pittsburgh, Pennsylvania, with additional updates presented at the Advanced Technology Applications for Combat Casualty Care 2010 Conference, August 16–19, 2010, in St. Pete Beach, Florida.

The opinions expressed in this document are solely those of the authors and do not represent an endorsement by or the views of the US Air Force, the US Army, the Department of Defense, or the US Government.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text, and links to the digital files are provided in the HTML text of this article on the journal’s Web site (

Address for reprints: Jeremy W. Cannon, MD, SM, Division of Traumatology, Surgical Critical Care & Emergency Surgery, Penn Presbyterian Medical Center, 51 N. 39th St., MOB Suite 120, Philadelphia, PA 19104; email:

© 2016 Lippincott Williams & Wilkins, Inc.