2019 Trauma/Critical Care Presentations

Sarah Thomas, MD1, Ryan Rhie, MPH1, Lydia Piper, MD1, James Aden, PhD1, Phillip Mason, MD1, Jennifer Gurney, MD2, James Lantry, MD3, Terry Lonergan, MD3, Brendan Beely, RRT4, Daniel Wendorff4, Andriy Batchinsky, MD4, Valerie Sams, MD1; 1SAMMC, 2ISR, 3Baltimore CSTARS, 4Geneva Foundation

OBJECTIVES: Combat injury patterns in Operations Iraqi and Enduring Freedom have changed as a result of wounding mechanisms and protective gear resulting in patients surviving highly lethal injuries.  Advances in critical care in the deployed environment and during transport has been a crucial component in the management of severely injured casualties.  ARDS presents a unique challenge in that many normal lung rescue modalities, such as nitric oxide, prone positioning, advanced ventilator techniques, and Extracorporeal Membrane Oxygenation (ECMO) are not readily employable in the deployed environment. This study seeks to determine any mortality risk factors or predictive patterns with ARDS in the combat wounded.

METHODS: We conducted a retrospective review of all US military personnel traumatically injured in theaters of operation from 2001-2015 identified as having a diagnosis of ARDS by ICD9 code. Using the Department of Defense Trauma Registry (DoDTR), we assessed demographics, prehospital and arrival vital signs and Glascow Coma Score (GCS), laboratory analysis, and mortality. Survivor and nonsurvivor groups were identified. Univariate analyses were performed with significance set at p≤0.05. Significant factors were then included in a multivariate logistic regression for mortality.

RESULTS: A total of 182 service members developed ARDS after trauma of which 42 were nonsurvivors (25% mortality).  Explosive injuries (67%) and gunshot wounds (15%) predominated. Higher mortality rates were seen among patients with higher Injury Severity Scores (ISS) (35 ± 18 vs 27 ± 13, p=0.012), lower platelet count (129 ± 103 vs 201 ± 202, p=0.008), higher INR (1.9 ± 1.0 vs 1.5 ± 0.5, p=0.033), lower base deficit (-9 ± 8 vs -3 ± 7, p=0.001) and lower pH (7.2 ± 0.1 vs 7.3 ± 0.1, p=0.013) upon arrival. Additionally, higher PaCO2 (48 ± 6 vs 45 ± 5, p=0.014) at arrival was associated with increased mortality. There was no difference between survivors and nonsurvivors vital signs upon arrival to ED, pre-arrival vitals, or GCS. Multivariate logistic regression showed ISS, PaCO2, and base deficit remained significant with an AUC of 0.84

CONCLUSIONS: Given the high mortality associated with ARDS in combat casualties, innovative rescue strategies should be considered to employ in the downrange environment and along the continuum of care.  ECMO has been utilized for years for ARDS and has been increasing in the adult trauma population.  As innovations in device technology and advances in techniques evolve, ECMO can be further incorporated into the downrange care paradigm.