'Optimizing combat casualty care’ in the out-of-hospital environment by providing emergency care research designed to fill the capability gaps existing in Tactical Combat Casualty Care (TCCC).
(1) Advanced clinical competency of military medical personnel in emergency medicine
(2) Evidence-based support for the TCCC paradigm (tactical field care and evacuation [TACEVAC])
(3) Development of Remote Damage Control Resuscitation (RDCR) for mitigating the deleterious effects of hemorrhage and the “Lethal Triad”
(4) Development of advanced decision support systems for guiding life-saving interventions (LSI):
The TCCC Research Task Area portfolio includes:
(1) support of TCCC doctrine development and advanced clinical competency in emergency medical personnel (e.g., medics) through retrospective analysis of combat casualty data obtained from the Joint Theatre Trauma System (JTTS) and Armed Forces Medical Examiner (AFME) databases.
(2) The Remote Damage Control Resuscitation (RDCR) initiative.
(3) Emergency telemedical direction.
(4) Out-of-hospital trauma patient data collection and analysis for clinical validation and demonstration of TCCC and RDCR paradigms prior to translation to the battlefield
(5) Research and development of diagnostic and therapeutic medical devices and associated algorithms, software and data processing systems that can provide new, advanced decision-assist capabilities to assist combat medical personnel with earlier intervention for remote triage, resuscitation, stabilization, life-support, and surgical support; and 6) development support for an integrated Critical Care System for Trauma And Transport (CCSTAT) capability.
A capability gap exists in the scope-of-practice and clinical competency of pre-hospital combat casualty care providers. The TCCC Research Task Area plans to bridge this gap by initiating field research conducted in civilian and battlefield environments designed to provide evidence for development of professional medical oversight, clinically-validated operating guidelines or protocols, and an integrated network of initial tactical medical care, medical evacuation with care continuing en route, and coordination with destination surgical facilities.
Research activities also include investigations of the impacts on competency of emergency telemedical direction designed to provide primary care direction to physician-lead resuscitation teams in simulated casualty care scenarios.
Another capability gap is the subpopulation of preventable combat deaths resulting from the lethal combination of non-compressible truncal hemorrhage (NCTH), environmental effects and protracted time intervals between initial injury and access to resuscitation and hemostatic surgery.
In order to bridge this gap, a RDCR capability must be established. Building upon doctrine developed by the Committee on Tactical Combat Casualty Care (CoTCCC), RDCR might employ advanced monitors and point-of-care diagnostics designed to assess or predict NCTH during the tactical field care or tactical evacuation phases.
Interventions might include lower volume intravenous colloid fluid infusion in the form of freeze-dried or spray-dried plasma. With the advent of field-deployable thromboelastography, it may also become possible to administer freeze-dried platelets, targeted pro-coagulants or antifibrinolytics.
Eventually, hemoglobin based oxygen carriers (HBOC) or even whole-blood substitutes might become available for employment in a future RDCR paradigm. The TCCC Research Task Area is addressing this challenge by initiating data acquisition and test-bed establishment for a Remote Trauma Outcomes Research Network (RemTORN).
The purpose of this research is to establish a physical and personnel infrastructure for the collection of both out-of-hospital (initial response and inter-facility) and linked inpatient clinical data for trauma patients undergoing initial stabilization at outlying Texas Department of State Health Services (DSHS) Level-IV trauma centers (no emergency surgical capability) followed by transfer to Level-I trauma centers, and to initiate observational studies of physiologic monitoring, coagulation status, injury severity and en route care in anticipation of subsequent clinical trials to support RCDR treatment protocols.
Hemorrhage is the most prevalent cause of death on the battlefield, accounting for 85% of “potentially survivable” deaths. Specifically, the inability to accurately identify non-compressible and uncontrolled truncal hemorrhage is a capability gap at nearly all levels of care in both military and civil sector settings, and contributes significantly to the number of “potentially survivable” deaths.Some of these deaths might be avoided if military medical personnel, in addition to advanced training, were equipped with monitors capable of assessing the presence and severity of hemorrhage in its earliest stages, facilitating both earlier performance of life-saving interventions as well as more efficient triage and evacuation decision-making. In addition, the inability to monitor accurate resuscitation is also a capability gap. Diagnosing hemorrhagic shock before hemodynamic instability or overt shock will allow for avoidance of over-resuscitation and the rapid increase in systolic blood pressure and concomitant dilution of the clotting factors, which may result in the failure of initially-forming clots.
The potential to ameliorate the acute coagulopathy of trauma with freeze- or spray-dried blood products currently under development will further intensify the importance of the early diagnosis of hemorrhage, and may enable pre-hospital employment of these products by combat medics and civil sector emergency medical services personnel.
As such, algorithm-based physiological monitors hold the potential to decrease morbidity and mortality in the hemorrhaging patient in the pre-hospital setting. Unfortunately, current vital signs monitors do not provide the specificity or sensitivity required for early assessment of casualties with hemorrhage and pending hemodynamic instability because they are limited to a point in time measurement, fail to assess trends over time, and may manifest delayed changes due to compensatory mechanisms.
Decision-support systems designed for determining the severity of blood loss or other causes of impending hemodynamic instability, or for guiding resuscitation in such patients, are not accessible in the current environment. The TCCC Task Area plans to bridge these gaps by conducting laboratory research that can lead to the development of accurate algorithms that reflect changes in the intravascular blood volume over time.
With this objective in mind, a primary challenge to the development of such algorithms is obtaining physiological signals that reflect changes in circulating blood volume. This challenge is virtually impossible in the clinical setting.
Through research conducted by investigators in the TCCC Research Task Area, the use of lower body negative pressure (LBNP) has been validated as a human model of the early compensatory stage of hemorrhage.
As such, LBNP has proven to be a valuable research platform for providing continuous physiological signals that can be incorporated in machine-learning algorithms for early detection of progression toward hemorrhagic instability (e.g., shock) and guidance for accurate fluid resuscitation.
The inability of the combat medic to remotely monitor injured warfighters on the battlefield remains a capability gap for accurate and rapid triage of casualties. In an effort to bridge this gap, the TCCC Research Task Area continues to support research experiments designed for the development of machine-learning algorithms embedded into a wearable sensor suite and provide a remote triage capability.
The sensors being integrated for decision support of combat casualty care include life sign detection (heart rate and respiration), ballistic wound detection and movement. The incorporation of novel physiological sensors and algorithms capable of tracking blood volume status (i.e., severity of hemorrhage) will provide the combat medic with remotely advanced situational awareness that identifies the existence and status of a casualty, and an ability to assess the risk of exposure to harms way.
It is well documented in the trauma literature that a cohort of patients (29% to 44%) respond to severe bleeding with a relative bradycardia, i.e., the inability to mount a robust elevation in heart rate.
Most importantly, relative bradycardia in hypotensive patients can be associated with increased mortality. Our laboratory experiments are consistent with the trauma literature in that these ‘non-responders’ are at high risk of developing early hemodynamic instability during hemorrhage compared to those who are able to mount a high heart rate response.
The challenge of understanding the physiological compensatory responses to progressive hemorrhage in trauma patients is complicated by the existence of two sub-populations with distinctly different physiological capacities to respond to blood volume loss.
Our Task Area investigators have also identified other physiological signals (e.g., oscillations in arterial waveforms and cerebral blood flow) that are dramatically different in low compared to high ‘responders’.
The inability of current monitoring algorithms to distinguish low from high heart rate ‘responders’ represents a capability gap for early identification and triage for those at greatest risk of developing overt shock.
The LBNP model has been used to demonstrate the effectiveness of an Impedance Threshold Device (ITD) in markedly improving blood flow to the heart and the brain.
This technology has proven effective in improving survival by ~50% in the clinical setting of out-of-hospital cardiac arrest when used with standard cardiopulmonary resuscitation.
Our current research has demonstrated that the ITD could prove to be an important adjunct for delaying the onset of hemorrhagic shock since it successfully delayed the onset of symptoms and hemodynamic decompensation during progressive loss of central blood volume (i.e., simulated hemorrhage) in humans.
The ITD also holds potential as an intervention for the treatment of traumatic brain injury (TBI) because of its effectiveness in reducing intracranial pressure in an animal model of TBI.
The activities of the TCCC Research Task Area will continue to focus on the integration of data generated from civilian trauma, military battlefield, and laboratory platforms that represent the period of out-of-hospital care and transport from the point-of-injury to arriving at a Role 3 facility.
Our future objective is to provide evidence-based guidelines, practices and technologies to support: 1) the TCCC paradigm; 2) training and telemedicine for advanced clinical competency of military medical personnel; 3) development of Remote Damage Control Resuscitation; and 4) advancement of monitoring decision-support systems for guiding life-saving interventions.
This integrated approach will be founded on understanding the underlying physiological processes occurring during the early, compensatory stage of hemorrhagic shock.
Crosstalk between these research platforms allows us to provide data-driven solutions that will bridge critical capability gaps outlined by the CoTCCC.