Article 1
Influence of Time to Transport to a Higher Level Facility on the Clinical Outcomes of US Combat Casualties with TBI: A Multicenter 7-Year Study. Maddry JK, Arana AA, Perez CA, Medellin KL, Paciocco JA, Mora AG, Holder WG, Davis WT, Herson PS, Bebarta VS. Military Medicine. 2020 Feb; 185 (1-2): e138-e145.
Traumatic Brain Injury (TBI) is a leading cause of disability and mortality worldwide. A large majority of combat casualties suffer TBI. Prehospital care aimed at preventing hypoxia, hypocapnia, hypercapnia, and hypotension aim to improve neurologic outcomes of those that sustain TBI. Survival of combat-related traumatically injured patients have improved over the years due to the use of aeromedical evacuation utilizing Critical Care Air Transport Teams (CCATT) composed of a critical care physician, a critical care nurse, and respiratory therapist who are specially trained at managing complex polytrauma patients with critical care needs. Although rapid evacuation via CCATT from the combat theaters is favored in order to initiate advanced therapies, there are concerns that exposure to hypobaric and hypoxic environments worsen outcomes. The optimal time to transport TBI patients is currently not known. The aim of this study is to characterize patients with TBI and evaluate the association between clinical outcomes and time to aeromedical transport from combat theaters via CCATT.
This study performed a retrospective chart review of CCATT patients with TBI transported out of the combat theater between January 2007 and May 2014 to Landstuhl Regional Medical Center (LRMC). A data query of the Department of Defense Trauma Registry (DoDTR) was performed to identify patients with moderate to severe TBI who were evacuated from a combat theater hospital to higher level of care at LRMC via CCATT. The CCATT records of these patients were then obtained. Those without a CCATT record or were under 18 years of age were excluded. Data such as flight transport information, vital signs, Glasgow Coma Scale (GCS), laboratory values, medications, procedures, in-flight assessments and interventions, and outcomes were obtained. Ultimately, 477 patients fit the study inclusion criteria. Compared to those transported in one day or less, patients who were evacuated from theater after three days or more were 70% less likely to be ventilated at discharge, had higher GCS at discharge, had lower odds of mortality, and were more likely to return to duty or discharged home. In the statistical analyses using multivariable logistic regression models, longer times to transport (2 to > 3 days), had better outcomes than more immediate transport, even after adjusting for ISS, polytrauma, head/neck AIS severity score, blast injury, cranial fractures, intracranial hemorrhage, need for pre-flight blood products, and surgical procedures.
In critically ill patients with moderate to severe TBI, optimal time to transport from a combat theater hospital to a higher-level facility has not been fully characterized. This study demonstrated that longer time to transport at two to three days after injury was associated with improved mortality rates and a higher likelihood of discharging to home or return to duty. There are several limitations to this study: it is retrospective in nature, and, although several confounding variables were considered and adjusted for in the statistical analyses, they do not capture the individual provider’s clinical judgment and gestalt of the patient that may have prompted a sense of urgency for evacuation within one day. Nevertheless, the results of this study confer that there may be benefit in exercising prudence and transporting moderate/severe TBI patients after necessary procedures and stabilization have been accomplished.
Article 2
Abdominal Aortic and Junctional Tourniquet Versus Zone III Resuscitative Endovascular Balloon Occlusion of the Aorta in a Swine Junctional Hemorrhage Model. Schechtman DW, Kauvar DS, De Guzman R, Polykratis A, Prince MD, Kheirabadi, BS, Dubick MA. J Trauma Acute Care Surgery. 2020 Feb; 88 (2): 292-297.
Most of the potentially preventable deaths in the battlefield occur prior to the casualty with junctional and noncompressible torso hemorrhage (NCTH) reaching surgical care. Strategies that can address junctional and noncompressive torso hemorrhage in the austere military prehospital setting are vital to improving mortality in this population of the combat injured. Currently, there are two possible treatment modalities that can control hemorrhage in this patient population: the Abdominal Aortic and Junctional Tourniquet (AAJT), an approved device that provides a field-capable external abdominal vascular occlusion to control pelvic and inguinal junctional hemorrhage, and Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) inflated in the infrarenal aortic (Zone III) position. Both function by limiting arterial blood flow below the level of the device. AAJT is applied externally and can be applied with minimal training, while REBOA placement requires more extensive training. This paper compared the ability of AAJT and zone III REBOA in controlling junctional hemorrhage in a large animal model.
This study used a swine model with a period of controlled hemorrhage of 20mL/kg at 100mL/min through a femoral artery catheter. This was then followed by a fracture of the midshaft of the left femur to add a traumatic injury to the hemorrhage model. A 50% circumferential laceration was then made to the right femoral artery that was allowed to bleed freely for 15 minutes to bring the animal’s total blood loss to 40% of estimated blood volume before either the AAJT was placed around the abdomen and inflated to 250mmHg or the REBOA was positioned at Zone III and the balloon inflated. Hemodynamics and laboratory values were assessed.
There was no difference in survival between the AAJT and REBOA groups. Both achieved hemostasis and MAP restoration. Furthermore, there were no significant differences in junctional arterial hemostasis and physiologic impact between the two groups. Both also demonstrated similar metabolic derangements with lactic acidosis and hyperkalemia during and after intervention. This suggests that both interventions are time-limited due to ischemia-reperfusion injury.
Based on this study’s results demonstrating similar outcomes for AAJT and REBOA, the selection for the appropriate device in the prehospital, austere battlefield setting will depend on ease of use and low complication profile. REBOA, while requiring extensive training for arterial access and proper insertion, offers a more flexible intervention by providing more proximal aortic occlusion and a resuscitation adjunct with invasive blood pressure monitoring as an arterial line. While both have broadly similar complication profiles overall, prolonged AAJT use past one hour are associated with severe metabolic derangements and paraplegia. Zone 3 REBOA appears to be generally safer than AAJT past one hour but can have device-specific complications related to arterial access and balloon placement that can be severe. More studies are warranted to further characterize their uses, indications, and complication profiles to determine which of the two strategies is the better selection in the prehospital austere battlefield setting in controlling junctional hemorrhage.
