Airborne! UAV delivery of blood products and medical logistics for combat zones.

BACKGROUND: Innovative solutions to resupply critical medical logistics and blood products may be required in future near-peer conflicts. Unmanned aerial vehicles (UAVs) are increasingly being used in austere environments and may be a viable platform for medical resupply and the transport of blood products. METHODS: A literature review on PubMed and Google Scholar up to March of 2022 yielded a total of 27 articles that were included in this narrative review. The objectives of this article are to discuss the current limitations of prehospital blood transfusion in military settings, discuss the current uses of UAVs for medical logistics, and highlight the ongoing research surrounding UAVs for blood product delivery. DISCUSSION: UAVs allow for the timely delivery of medical supplies in numerous settings and have been utilized for both military and civilian purposes. Investigations into the effects of aeromedical transportation on blood products have found minimal blood product degradation when appropriately thermoregulated and delivered in a manner that minimizes trauma. UAV delivery of blood products is now actively being explored by numerous entities around the globe. Current limitations surrounding the lack of high-quality safety data, engineering constraints over carrying capacity, storage capability, and distance traveled, as well as air space regulations persist. CONCLUSION: UAVs may offer a novel solution for the transport of medical supplies and blood products in a safe and timely manner for the forward-deployed setting. Further research on optimal UAV design, optimal delivery techniques, and blood product safety following transport should be explored prior to implementation.

Tactical Neurocritical Care.

Neurocritical care is usually practiced in the comfort of an intensive care unit within a tertiary care medical center. Physicians deployed to the frontline with the US military or allied military are required to use their critical care skills and their neurocritical skills in austere environments with limited resources. Due to these factors, tactical critical care and tactical neurocritical care differ significantly from traditional critical care. Operational constraints, the tactical environment, and resource availability dictate that tactical neurocritical care be practiced within a well-defined, mission-constrained framework. Although limited interventions can be performed in austere conditions, they can significantly impact patient outcome. This review focuses on the US Army approach to the patient requiring tactical neurocritical care specifically point of injury care and care during transportation to a higher level of care.

Prolonged Field Care: Beyond the "Golden Hour".

Prolonged field care (PFC) has emerged as a recent area of focus for US military Special Operations Forces (SOF) medical experts. Focused on the current reality of providing medical care to military forces often deployed in remote and austere locations far from medical support or a robust casualty evacuation chain, PFC encompasses evolving operational situations not unlike many wilderness medicine practice environments. SOF currently operates in all areas of the world and on a variety of different missions, which finds these small teams far from the accustomed practice environment of robust deployed medical infrastructure commonly seen during the last 15 years of military conflicts. In light of this evolving operational situation, the Prolonged Field Care Working Group has undertaken a comprehensive approach to better define and tackle this challenge. The approach to training and educating SOF medics on PFC is based on defined capabilities and operational situations that incorporate best medical practices and seeks to place advance resuscitative capabilities into the hands of providers closest to the point of injury. By transitioning from an approach solely driven by acute trauma aide, incorporating the best practices of Tactical Combat Casualty Care (TCCC), PFC builds upon best practices for the continuing management of both medical and trauma patients in wilderness environments. PFC incorporates best practices in generally hospital-based management of serious and critical casualties to decrease both mortality and morbidity in austere, prehospital operational settings.

Integration of Tactical EMS in the National Park Service.

The National Park Service (NPS) has domestic responsibility for emergency medical services (EMS) in remote and sometimes tactical situations in 417 units covering over 34 million hectares (84 million acres). The crossover between conflicting patient care priorities and complex medical decision making in the tactical, technical, and wilderness/remote environments often has many similarities. Patient care in these diverse locations, when compared with military settings, has slightly different variables but often similar corresponding risks to the patients and providers. The NPS developed a Tactical EMS (TEMS) program that closely integrated many principles from: 1) Tactical Combat Casualty Care (TCCC); 2) Tactical Emergency Casualty Care (TECC); 3) and other established federal and civilian TEMS programs. Combining these best practices into the NPS TEMS Program allowed for standardized training and implementation across not only the NPS, but also paralleled other military/federal/civilian TEMS programs. This synchronization is critical when an injury occurs in a joint tactical operation, either planned (drug interdiction) or unplanned (active shooter response), so that patient care can be uniform and efficient. The components identified for a sustainable TEMS program began with strong medical oversight, protocol development with defined phases of care, identifying specialized equipment, and organized implementation with trained TEMS instructors. Ongoing TEMS program management is continuously improving situationally appropriate training and integrating current best practices as new research, equipment, and tactics are developed. The NPS TEMS Program continues to provide ongoing training to ensure optimal patient care in tactical and other NPS settings.

Lessons from the Fallen: An After-Action Review of Prehospital Casualty Data during the Global War on Terror.

BACKGROUND: The US military's recent involvement in long standing conflict has caused the pioneering of many lifesaving medical advances, often made possible by data-driven research. However, future advances in battlefield medicine will likely require greater data fidelity than is currently attainable. Continuing to improve survival rates will require data which establishes the relative contributions to preventable mortality and guides future interventions. Prehospital data, particularly that from Tactical Combat Casualty Care (TCCC) Cards and TCCC After Action Reports (TCCC AARs), are notoriously inconsistent in reaching searchable databases for formal evaluation. While the military has begun incorporating more modern technology in advanced data capture over the past few years like the Air Force's Battlefield Assisted Trauma Distributed Observation Kit (BATDOK) and the Army's Medical Hands-free Unified Broadcast system (MEDHUB), more analysis weighing the advantages and disadvantages of substituting analog solutions is needed. DISCUSSION: We propose 3 changes which may aid prehospital data capture and facilitate analysis: reexamine the current format of TCCC Cards and consider reducing the number of available datapoints to streamline completion, implement a military-wide mandate for all Role 1 providers to complete a TCCC AAR within 24 hours of a casualty event, and formalize the process of requesting de-identified data from the Armed Forces Medical Examiner System (AFMES) database. CONCLUSION: Reflecting on the state of US military medicine after 20 years of war, an important focus is improving the way prehospital data is gathered and analyzed by the military. There are steps we can take now to enhance our capabilities.

Admission Forced Vital Capacity Adds a Predictive Physiologic Tool to Triage Patients Suffering Rib Fractures: A Prospective Observation Trial.

BACKGROUND: Patients with rib fractures are at high risk for morbidity and mortality. This study prospectively examines bedside percent predicted forced vital capacity (% pFVC) in predicting complications for patients suffering multiple rib fractures. The authors hypothesize that increased % pFVC is associated with reduced pulmonary complications. METHODS: Adult patients with =3 rib fractures admitted to a level I trauma center, without cervical spinal cord injury or severe traumatic brain injury, were consecutively enrolled. FVC was measured at admission and % pFVC values were calculated for each patient. Patient were grouped by % pFVC <30% (low), 30-49% (moderate), and =50% (high). RESULTS: A total of 79 patients were enrolled. Percent pFVC groups were similar except for pneumothorax being most frequent in the low group (47.8% vs. 13.9% and 20.0%, p = .028). Pulmonary complications were infrequent and did not differ between groups (8.7% vs. 5.6% vs. 0%, p = .198). DISCUSSION: Increased % pFVC was associated with reduced hospital and intensive care unit (ICU) length of stay (LOS) and increased time to discharge to home. Percent pFVC should be used in addition to other factors to risk stratify patients with multiple rib fractures. Bedside spirometry is a simple tool that can help guide management in resource-limited settings, especially in large-scale combat operations. CONCLUSION: This study prospectively demonstrates that % pFVC at admission represents an objective physiologic assessment that can be used to identify patients likely to require an increased level of hospital care.

Bilateral Pneumothoraces in a Tandem Parachuting Passenger Without Traumatic Impact: A Case Report.

In parachuting, orthopedic and head injuries are well-documented risks associated with the parachute deployment and landing phases. Thoracic injuries have only been seen on rare occasion in conjunction with direct impact trauma. In this report, we detail a case of a young, healthy, tandem skydiving passenger who suffered bilateral pneumothoraces with delayed symptom onset, with no identifiable injury during the jump or landing. Exploring the forces of the parachute "opening shock," we suggest a plausible compressive mechanism for this novel presentation, as well as briefly discuss the options for diagnosis and conservative management of pneumothorax in the operational context. While this is an exceedingly rare event, pneumothorax should be considered in patients complaining of thoracic symptoms following a skydive.

Noninvasive Monitoring of Simulated Hemorrhage and Whole Blood Resuscitation.

Hemorrhage is the leading cause of preventable death from trauma. Accurate monitoring of hemorrhage and resuscitation can significantly reduce mortality and morbidity but remains a challenge due to the low sensitivity of traditional vital signs in detecting blood loss and possible hemorrhagic shock. Vital signs are not reliable early indicators because of physiological mechanisms that compensate for blood loss and thus do not provide an accurate assessment of volume status. As an alternative, machine learning (ML) algorithms that operate on an arterial blood pressure (ABP) waveform have been shown to provide an effective early indicator. However, these ML approaches lack physiological interpretability. In this paper, we evaluate and compare the performance of ML models trained on nine ABP-derived features that provide physiological insight, using a database of 13 human subjects from a lower-body negative pressure (LBNP) model of progressive central hypovolemia and subsequent progressive restoration to normovolemia (i.e., simulated hemorrhage and whole blood resuscitation). Data were acquired at multiple repressurization rates for each subject to simulate varying resuscitation rates, resulting in 52 total LBNP collections. This work is the first to use a single ABP-based algorithm to monitor both simulated hemorrhage and resuscitation. A gradient-boosted regression tree model trained on only the half-rise to dicrotic notch (HRDN) feature achieved a root-mean-square error (RMSE) of 13%, an R2 of 0.82, and area under the receiver operating characteristic curve of 0.97 for detecting decompensation. This single-feature model's performance compares favorably to previously reported results from more-complex black box machine learning models. This model further provides physiological insight because HRDN represents an approximate measure of the delay between the ABP ejected and reflected wave and therefore is an indication of cardiac and peripheral vascular mechanisms that contribute to the compensatory response to blood loss and replacement.

An Updated Review of Improvised Ground Evacuation Platforms for Austere Special Operations Casualty Transport.

INTRODUCTION: In 2018, the Expeditionary Resuscitative Surgical Team 3 (ERST-3) published a retrospective review on the ground casualty evacuation (CASEVAC) options available to a Special Operations Forces (SOF) unit in the Horn of Africa. Seventeen months following their deployment, ERST-7 provided an update on the improvised ground evacuation platforms in the same area of operations and what has and has not worked based on combat experience and new literature. METHODS: This publication is an update to a retrospective review of various modes of ground transportation used by ERST-7 during their deployment with Special Operations Command Africa from July 2020 to January 2021. The authors excluded all hand-carried litter and air evacuation platforms. The authors discuss litter setup, necessary modifications, litter capacity, strengths and weaknesses, and any recommendations for a Mine-Resistant Ambush Protected (MRAP) vehicle, a full-size pickup truck, and a mid-size pickup truck based on their use during the ERST-7 deployment. The authors also used previous literature to support their recommendations. RESULTS: The SOF unit to which ERST-7 was assigned still uses two of the four platforms included in the original study. The authors recommend continued use of the MRAP for patient extraction with a solely widthwise patient configuration, weather-proofing the open beds of MRAPs, and outfitting all MRAPs for Tactical Combat Casualty Care (TCCC) if the CASEVAC-designated MRAP is disabled. The pickup trucks functioned well for expedient CASEVAC under non-hostile conditions. However, they should be a last resort for CASEVAC outside friendly-controlled areas due to inadequate cover and concealment for patients and medical personnel providing enroute care. CONCLUSIONS: Vehicles of opportunity available to SOF personnel are constantly changing. Continuous evaluation of local platforms is crucial, especially for partner force personnel who may not have access to dedicated air and ground MEDEVAC platforms. The authors recommend baseline readiness training on CASEVAC scenarios for those units traveling to areas without MEDEVAC assets.

Percutaneous delivery of self-propelling hemostatic powder for managing non-compressible abdominal hemorrhage: a proof-of-concept study in swine.

INTRODUCTION: Non-compressible intra-abdominal hemorrhage (NCIAH) is a major cause of preventable death on the battlefield and in civilian trauma. Currently, it can only be definitively managed with surgery, as there are limited strategies for controlling ongoing NCIAH in the prehospital environment. We hypothesized that a self-propelling thrombin-containing powder (SPTP) could increase survival in a swine model of NCIAH when delivered percutaneously into the closed abdomen using an engineered spray system. MATERIALS AND METHODS: Nineteen swine underwent surgical laparotomy followed by a Grade V liver injury that created massive hemorrhage, before closing the abdomen with sutures. Animals either received treatment with standard of care fluid resuscitation (n=9) or the SPTP spray system (n=10), which consisted of a spray device and a 14 Fr catheter. Using the spray system, SPTP was delivered into a hemoperitoneum identified using a focused assessment with sonography in trauma (FAST) exam. Lactated Ringer's solution was administered to all animals to maintain a mean arterial pressure (MAP) of >50 mmHg. The primary outcome was percentage of animals surviving at three hours following injury. RESULTS: In the swine model of NCIAH, a greater percentage of animals receiving SPTP survived to three hours, although differences were not significant. The SPTP spray system increased the median survival of animals from 1.6 hr in the fluid resuscitation group to 4.3 hr. The SPTP spray system delivered a total mass of 18.5 ± 1.0 g of SPTP. The mean change in intra-abdominal pressure following SPTP delivery was 5.2 ± 1.8 mmHg (mean ± SEM). The intervention time was 6.7 ± 1.7 min. No adverse effects related to the SPTP formulation or the spray system were observed. SPTP was especially beneficial in animals that had either severely elevated lactate concentrations or low mean arterial pressure of <35 mmHg shortly after injury. CONCLUSIONS: This demonstrates proof-of-concept for use of a new minimally invasive procedure for managing NCIAH, which could extend survival time to enable patients to reach definitive surgical care.

Experience With Trauma-Induced ARDS: A Retrospective Study of US Wartime Casualties 2003-2015.

BACKGROUND: The purpose of our study was to assess risks/ outcomes of acute respiratory distress syndrome (ARDS) in US combat casualties. We hypothesized that combat trauma patients with ARDS would have worse outcomes based on mechanism of injury (MOI) and labs/vital signs aberrancies. MATERIALS AND METHODS: We reviewed data on military Servicemembers serving in Iraq and Afghanistan from 1 January 2003 to 31 December 2015 diagnosed with ARDS by ICD-9 code. We extracted patient demographics, injury specifics, and mortality from the Department of Defense Trauma Registry (DoDTR). RESULTS: The most common MOI was an explosion, accounting for 67.6% of all injuries. Nonsurvivors were more likely to have explosion-related injuries, have higher injury severity score (ISS), higher international normalized ratio (INR), lower platelet count, greater base deficit, lower temperature, lower Glasgow Coma Scale (GCS) score, and lower pH. There was no significant difference in deaths across time. CONCLUSION: By identifying characteristics of patients with higher mortality in trauma ARDS, we can develop treatment guidelines to improve outcomes. Given the high mortality associated with trauma ARDS and relative paucity of clinical data available, we need to improve battlefield data capture to better guide practice and ultimately improve care. The management of ARDS will be increasingly relevant in prolonged casualty care (PCC; formerly prolonged field care) on the modern battlefield.

Airway and Hypothermia Prevention: and Treatment via STEAM The System for Thermogenic Emergency Airway Management.

Military medicine has made significant advancements in decreasing mortality by addressing the lethal triad - metabolic acidosis, coagulopathy, and hypothermia. However, casualties are still succumbing to injury. Recent conflict zones have led to the development of remarkable life-saving innovations, including the management of compressible hemorrhage and whole blood transfusions. Nevertheless, hypothermia prevention and treatment techniques remain relatively unchanged. Hypothermia prevention is anticipated to become more critical in future operations due to a predicted increase in evacuation times and reliance on Prolonged Casualty Care (PCC). This is likely secondary to increasingly distanced battlespaces and the mobility challenges of operating in semi-/non-permissive environments. Innovation is essential to combat this threat via active airway rewarming in the vulnerable patient. Thus, we propose the development, fabrication, and efficacy testing of a device in which we estimate being able to control temperature and humidity at physiologic levels in the PCC setting and beyond.

Systematic approach to delivering prolonged field care in a prehospital care environment.

BACKGROUND: This article describes a novel patient care algorithm which provides a Role 1 (R1) medic with a structured approach to delivering prolonged field care (PFC) in a resource-limited environment. PFC is a vital component of the operational patient care pathway providing the continuum of care from completion of a primary survey to the delivery to hospital care. Future operational environments are likely to have more fragile or extended lines of communication, potentially delaying evacuation to hospital care. This delay may lead to increases in patient morbidity and mortality. Effective PFC offers an opportunity to improve patient outcomes and help mitigate against this risk. METHODS: An initial prototype model of a PFC care process was developed using existing hospital-based guidance. A series of medical and trauma vignettes and best available evidence were used to refine the algorithm. RESULTS: The algorithm has been designed be used in conjunction with patient specific clinical guidance making the approach generalisable for all patient groups. For UK military, clinical guidance is provided by clinical guidelines for operations. The algorithm can be downloaded into a convenient format to be used on mobile devices or printed as an aide memoire.

An Evaluation of a Novel Medical Device Versus Standard Interventions in the Treatment of Tension Pneumothorax in a Swine Model (Sus scrofa).

INTRODUCTION: Tension pneumothorax is a common cause of preventable death in trauma. Needle decompression is the traditional first-line intervention but has high failure rates. We sought to evaluate the effectiveness and expedience of needle thoracostomy, surgical tube thoracostomy, and Reactor™ thoracostomy - a novel spring-loaded trocar insertion device. MATERIALS AND METHODS: Yorkshire swine underwent controlled thoracic insufflation to create tension pneumothorax physiology for device comparison. Additional experiments were performed by increasing insufflation pressures to achieve pulseless electrical activity. Intervention was randomized to needle thoracostomy (14 gauge), tube thoracostomy (32Fr), or Reactor™ thoracostomy (36Fr). Air leak was simulated throughout intervention with 40-80 mL/kg/min insufflation. Intrathoracic pressure monitoring and hemodynamic parameters were obtained at 1 and 5 minutes. RESULTS: Tension physiology and tension-induced pulseless electrical activity were created in all iterations. Needle thoracostomy (n = 28) was faster at 7.04 ± 3.04 seconds than both Reactor thoracostomy (n = 32), 11.63 ± 5.30 (p < 0.05) and tube thoracostomy (n = 32), 27.06 ± 10.73 (p < 0.01); however, Reactor™ thoracostomy was faster than tube thoracostomy (p < 0.001). Physiological decompression was achieved in all patients treated with Reactor™ and tube thoracostomy, but only 14% of needle thoracostomy. Cardiac recovery to complete physiologic baseline occurred in only 21% (6/28) of those treated with needle thoracostomy whereas Reactor™ or tube thoracostomy demonstrated 88% (28/32) and 94% (30/32) response rates. When combined, needle thoracostomy successfully treated tension pneumothorax in only 4% (1/28) of subjects as compared to 88% (28/32) with Reactor™ thoracostomy and 94% (30/32) with tube thoracostomy (p < 0.01). CONCLUSIONS: Needle thoracostomy provides a rapid intervention for tension pneumothorax, but is associated with unacceptably high failure rates. Reactor™ thoracostomy was effective, expedient, and may provide a useful and technically simpler first-line treatment for tension pneumothorax or tension-induced pulseless electrical activity.

Evaluation of prolonged 'Permissive Hypotension': results from a 6-hour hemorrhage protocol in swine.

BACKGROUND: Tactical Combat Casualty Care guidelines for hemorrhage recommend resuscitation to systolic blood pressure (SBP) of 85±5 mm Hg during prehospital care. Success depends on transport to definitive care within the 'golden hour'. As future conflicts may demand longer prehospital/transport times, we sought to determine safety of prolonged permissive hypotension (PH). METHODS: Adult male swine were randomized into three experimental groups. Non-shock (NS)/normotensive underwent anesthesia only. NS/PH was bled to SBP of 85±5 mm Hg for 6 hours of prolonged field care (PFC) with SBP maintained via crystalloid, then recovered. Experimental group underwent controlled hemorrhage to mean arterial pressure 30 mm Hg until decompensation (Decomp/PH), followed by 6 hours of PFC. Hemorrhaged animals were then resuscitated with whole blood and observed for 24 hours. Physiologic variables, blood, tissue samples, and neurologic scores were collected. RESULTS: Survival of all groups was 100%. Fluid volumes to maintain targeted SBP in PFC were significantly higher in the hemorrhage group than sham groups. After 24 hours' recovery, no significant differences were observed in neurologic scores or cerebrospinal fluid markers of brain injury. No significant changes in organ function related to treatment were observed during PFC through recovery, as assessed by serum chemistry and histological analysis. CONCLUSIONS: After 6 hours, a prolonged PH strategy showed no detrimental effect on survival or neurologic outcome despite the increased ischemic burden of hemorrhage. Significant fluid volume was required to maintain SBP-a potential logistic burden for prehospital care. Further work to define maximum allowable time of PH is needed. STUDY TYPE: Translational animal model. LEVEL OF EVIDENCE: N/A.

Tactical tourniquet: Surgical management must be within 3 hours.

Despite longstanding controversy, tourniquets are widely used in tactical combat casualty care, with undisputed benefits for recent conflicts in Iraq and Afghanistan. Increased time delays are a particular issue in large areas, such as the Sahel-Saharan band. Complications associated with tourniquet use are predominantly related to acute ischemia with risk of amputation and ischaemia-reperfusion injury, as shown in the first clinical case. Often stated but poorly described, misuse of tourniquet and subsequent failure to interrupt arterial blood flow is also a clinical scenario that should be recognized. In the case of misuse of the tourniquet, more significant blood loss may be expected because of venous compression (« venous tourniquet ¼, second clinical case). Early medical re-evaluation of the tourniquet is an essential component in prolonged field care. This includes reassessment of the tourniquet's ability to achieve hemostasis, abolish the downstream pulse and the relevance of the tourniquet altogether. This combat tool requires training to be successful and complications are time dependent. Tourniquet use requires appropriate application, re-evaluation and triage of wounded personnel within 3 h towards more structured surgical management.

PWD: Treatment Platform for Both Prolonged Field Care and Definitive Treatment of Burn-Injured Warfighters.

INTRODUCTION: Burns are a very frequent injury type in the battlefield, comprising 5-20% of combat casualties in the recent conflicts. Almost 80% of the burns occur to the face, in part because the face is often not protected. Immediate treatment is critical in the first hours after severe burn injury in order to prevent infection and wound progression. Immediate treatment in the battlefield can be a serious challenge especially if the injury occurs in a remote area with limited transport options. Therefore, novel treatment modalities for prolonged field care when transport to the definitive care is delayed are needed. The purpose of this study was to utilize the platform wound device (PWD) with negative pressure capabilities for the immediate and definitive treatment of porcine full-thickness head burns. MATERIALS AND METHODS: Full-thickness burn wounds were created on foreheads of seven Yorkshire pigs. Burns were created on day 0, immediately enclosed with the PWD and treated topically with minocycline and lidocaine. On day 3, the burns were surgically debrided. Subsequently, new PWDs were placed on the wounds and continuous negative pressure wound therapy was initiated with either -50 mmHg or -80 mmHg. On day 7, the animals were euthanized and wounds were harvested for analyses. Control wounds were treated with silver sulfadiazine cream. RESULTS: The PWD treatment with negative pressure significantly reduced erythema and edema in the injured tissue and promoted granulation tissue and neocollagen formation by day 7 in comparison to control wounds. In addition, the PWD with both topical minocycline and negative pressure (-80 mmHg or -50 mmHg) reduced bacterial counts in the wounds similar to the current standard of care. CONCLUSION: This study demonstrates that the PWD is an effective platform for delivery of antibiotics and negative pressure wound therapy for the treatment of full-thickness burns. Therefore, the PWD may be utilized for both prolonged field care and definitive treatment of burn- and blast-injured warfighters.