Awake Cricothyrotomy: A Novel Approach to the Surgical Airway in the Tactical Setting.

Airway obstruction on the battlefield is most often due to maxillofacial trauma, which may include bleeding and disrupted airway anatomy. In many of these cases, surgical cricothyrotomy (SC) is the preferred airway management procedure. SC is an emergency airway procedure performed when attempts to open an airway using nasal devices, oral devices, or tracheal intubation have failed, or when the risks from intubation are unacceptably high. The aim of this overview is to describe a novel approach to the inevitably surgical airway in which SC is the first and best procedure to manage the difficult or failed airway. The awake SC technique and supporting algorithm are presented along with the limitations and future directions. Awake SC, using local anesthetic with or without ketamine, will allow the knowledgeable provider to manage patients with a compromised airway across the continuum of emergency care ranging from remote/en route care, austere settings, and prehospital to the emergency department.

Analysis of Prehospital Documentation of Injury-Related Pain Assessment and Analgesic Administration on the Contemporary Battlefield.

In addition to life-saving interventions, the assessment of pain and subsequent administration of analgesia are primary benchmarks for quality emergency medical services care which should be documented and analyzed. Analyze US combat casualty data from the Department of Defense Trauma Registry (DoDTR) with a primary focus on prehospital pain assessment, analgesic administration and documentation. Retrospective cohort study of battlefield prehospital and hospital casualty data were abstracted by DoDTR from available records from 1 September 2007 through 30 June 2011. Data included demographics; injury mechanism; prehospital and initial combat hospital pain assessment documented by standard 0-to-10 numeric rating scale; analgesics administered; and survival outcome. Records were available for 8,913 casualties (median ISS of 5 [IQR 2 to 10]; 98.7% survived). Prehospital analgesic administration was documented for 1,313 cases (15%). Prehospital pain assessment was recorded for 581 cases (7%; median pain score 6 [IQR 3 to 8]), hospital pain assessment was recorded for 5,007 cases (56%; median pain score5 [CI95% 3 to 8]), and 409 cases (5%) had both prehospital and hospital pain assessments that could be paired. In this paired group, 49.1% (201/409) had alleviation of pain evidenced by a decrease in pain score (median 4,, IQR 2 to 5); 23.5% (96/409) had worsening of pain evidenced by an increase in pain score (median 3, CI95 2.8 to 3.7, IQR 1 to 5); 27.4% (112/409) had no change; and the overall difference was an average decrease in pain score of 1.1 (median 0, IQR 0 to 3, p < 0.01). Time-series analysis showed modest increases in prehospital and hospital pain assessment documentation and prehospital analgesic documentation. Our study demonstrates that prehospital pain assessment, management, and documentation remain primary targets for performance improvement on the battlefield. Results of paired prehospital to hospital pain scores and time-series analysis demonstrate both feasibility and benefit of prehospital analgesics. Future efforts must also include an expansion of the prehospital battlefield analgesic formulary.

A comparison of two open surgical cricothyroidotomy techniques by military medics using a cadaver model.

STUDY OBJECTIVE: The CricKey is a novel surgical cricothyroidotomy device combining the functions of a tracheal hook, stylet, dilator, and bougie incorporated with a Melker airway cannula. This study compares surgical cricothyroidotomy with standard open surgical versus CricKey technique. METHODS: This was a prospective crossover study using human cadaveric models. Participants included US Army combat medics credentialed at the emergency medical technician-basic level. After a brief anatomy review and demonstration, participants performed in random order standard open surgical cricothyroidotomy and CricKey surgical cricothyroidotomy. The primary outcome was first-pass success, and the secondary outcome measure was procedural time. RESULTS: First-attempt success was 100% (15/15) for CricKey surgical cricothyroidotomy and 66% (10/15) for open surgical cricothyroidotomy (odds ratio 16.0; 95% confidence interval 0.8 to 326). Surgical cricothyroidotomy insertion was faster for CricKey than open technique (34 versus 65 seconds; median time difference 28 seconds; 95% confidence interval 16 to 48 seconds). CONCLUSION: Compared with the standard open surgical cricothyroidotomy technique, military medics demonstrated faster insertion with the CricKey. First-pass success was not significantly different between the techniques.

Died of wounds on the battlefield: causation and implications for improving combat casualty care.

BACKGROUND: Understanding the epidemiology of death after battlefield injury is vital to combat casualty care performance improvement. The current analysis was undertaken to develop a comprehensive perspective of deaths that occurred after casualties reached a medical treatment facility. METHODS: Battle injury died of wounds (DOW) deaths that occurred after casualties reached a medical treatment facility from October 2001 to June 2009 were evaluated by reviewing autopsy and other postmortem records at the Office of the Armed Forces Medical Examiners (OAFME). A panel of military trauma experts classified the injuries as nonsurvivable (NS) or potentially survivable (PS), in consultation with an OAFME forensic pathologist. Data including demographics, mechanism of injury, physiologic and laboratory variables, and cause of death were obtained from the Joint Theater Trauma Registry and the OAFME Mortality Trauma Registry. RESULTS: DOW casualties (n = 558) accounted for 4.56% of the nonreturn to duty battle injuries over the study period. DOW casualties were classified as NS in 271 (48.6%) cases and PS in 287 (51.4%) cases. Traumatic brain injury was the predominant injury leading to death in 225 of 271 (83%) NS cases, whereas hemorrhage from major trauma was the predominant mechanism of death in 230 of 287 (80%) PS cases. In the hemorrhage mechanism PS cases, the major body region bleeding focus accounting for mortality were torso (48%), extremity (31%), and junctional (neck, axilla, and groin) (21%). Fifty-one percent of DOW casualties presented in extremis with cardiopulmonary resuscitation upon presentation. CONCLUSIONS: Hemorrhage is a major mechanism of death in PS combat injuries, underscoring the necessity for initiatives to mitigate bleeding, particularly in the prehospital environment.

Placement of tibial intraosseous infusion devices.

Post-mortem preautopsy multidetector computed tomography was used to assess the placement of tibial intraosseous infusion needles in 52 cases of battlefield trauma deaths for which medical intervention included the use of the technique. In 58 (95%) of 61 needles, the tip was positioned in medullary bone. All 3 (5%) unsuccessful placements were in the left leg, and the needle was not directed perpendicular to the medial tibial cortex as recommended. Considering the nature of military trauma and the environmental conditions under which care is rendered, military medical personnel appear to be highly successful in the placement of tibial intraosseous infusion needles.

Isolation of engineered, full-length antibodies from libraries expressed in Escherichia coli.

We describe facile isolation of full-length IgG antibodies from combinatorial libraries expressed in E. coli. Full-length heavy and light chains are secreted into the periplasm, where they assemble into aglycosylated IgGs that are captured by an Fc-binding protein that is tethered to the inner membrane. After permeabilizing the outer membrane, spheroplast clones expressing so-called E-clonal antibodies, which specifically recognize fluorescently labeled antigen, are selected using flow cytometry. Screening of a library constructed from an immunized animal yielded several antibodies with nanomolar affinities toward the protective antigen of Bacillus anthracis.

Fatal airway injuries during Operation Enduring Freedom and Operation Iraqi Freedom.

INTRODUCTION: Airway compromise is the third leading cause of potentially preventable death on the battlefield. An understanding of the injuries associated with fatal airway compromise is necessary to develop improvements in equipment, training, and prehospital management strategies in order to maximize survival. OBJECTIVE: To determine injury patters resulting in airway compromise in the combat setting. METHODS: This was a subgroup analysis of cases previously examined by Kelly and colleagues, who reviewed autopsies of military personnel who died in combat in Iraq and Afghanistan between 2003 and 2006. Casualties with potentially survivable (PS) injuries and deaths related to airway compromise previously identified by Kelly et al. were reviewed in depth by a second panel of military physicians. RESULTS: There were 982 cases that met the inclusion criteria. Of these, 232 cases had PS injuries. Eighteen (1.8%) cases were found to have airway compromise as the likely cause of primary death. All had penetrating injuries to the face or neck. Twelve deaths (67%) were caused by gunshot wounds, while six deaths (33%) were caused by explosions. Nine cases had concomitant injury to major vascular structures, and eight had significant airway hemorrhage. Cricothyroidotomy was attempted in five cases; all were unsuccessful. CONCLUSION: Airway compromise from battlefield trauma results in a small number of PS fatalities. Penetrating trauma to the face or neck may be accompanied by significant hemorrhage, severe and multiple facial fractures, and airway disruption, leading to death from airway compromise. Cricothyroidotomy may be required to salvage these patients, but the procedure failed in all instances in this series of cases. Further studies are warranted to determine the appropriate algorithm of airway management in combat casualties sustaining traumatic airway injuries.

L445P mutation on heavy chain stabilizes IgG4 under acidic conditions.

IgG4, a common type of therapeutic antibody, is less stable during manufacturing processes compared with IgG1. Aggregation and fragmentation are the two main challenges. Here, we report instability of the heavy chain (HC) C-terminal region under acidic conditions, which leads to cleavage and aggregation. Leu445, at the C-terminal region of the HC in IgG4, plays a critical role in its acid-induced fragmentation and subsequent aggregation. We found that mutating HC C-terminal Leu445 to Pro (the corresponding residue in IgG1) in IgG4_CDR-X significantly reduces fragmentation and aggregation, while mutating Pro445 to Leu in IgG1_CDR-X promotes fragmentation and aggregation. HC C-terminal Gly446 cleavage was observed in low pH citrate buffer and resulted in further fragmentation and aggregation, whereas, glycine buffer can completely inhibit the cleavage and aggregation. It is proposed that cleavages occur through acid-induced hydrolysis under acidic conditions and glycine stabilizes IgG4 via two main mechanisms: 1) product feedback inhibition of the hydrolysis reaction, and 2) stabilization of protein conformation by direct interaction with the peptide backbone and charged side chains. Experiments using IgG4 molecules IgG4_CDR-Y and IgG4_CDR-Z with the same CH domains as IgG4_CDR-X, but different complementarity-determining regions (CDRs), indicate that the stability of the HC C-terminal region is also closely related to the sequence of the CDRs. The stability of IgG4_CDR-X is significantly improved when binding to its target. Both observations suggest that there are potential interactions between Fab and CH2-CH3 domains, which could be the key factor affecting the stability of IgG antibodies.

Prehospital advances in the management of severe penetrating trauma.

BACKGROUND: Historic advances in combat prehospital care have been made in the last decade. Unlike other areas of critical care, most of these innovations are not the result of significant improvements in technology, but by conceptual changes in how care is delivered in a tactical setting. The new concept of Tactical Combat Casualty Care has revolutionized the management of combat casualties in the prehospital tactical setting. DISCUSSION: The Tactical Combat Casualty Care concept recognizes the unique epidemiologic and tactical considerations of combat care and that simply extrapolating civilian care concepts to the battlefield are insufficient. SUMMARY: This article examines the most recent and salient advances that have occurred in battlefield prehospital care driven by our ongoing combat experience in the Iraq and Afghanistan and the evolution around the Tactical Combat Casualty Care concept.

Measuring US Army medical evacuation: Metrics for performance improvement.

BACKGROUND: The US Army medical evacuation (MEDEVAC) community has maintained a reputation for high levels of success in transporting casualties from the point of injury to definitive care. This work served as a demonstration project to advance a model of quality assurance surveillance and medical direction for prehospital MEDEVAC providers within the Joint Trauma System. METHODS: A retrospective interrupted time series analysis using prospectively collected data was performed as a process improvement project. Records were reviewed during two distinct periods: 2009 and 2014 to 2015. MEDEVAC records were matched to outcomes data available in the Department of Defense Trauma Registry. Abstracted deidentified data were reviewed for specific outcomes, procedures, and processes of care. Descriptive statistics were applied as appropriate. RESULTS: A total of 1,008 patients were included in this study. Nine quality assurance metrics were assessed. These metrics were: airway management, management of hypoxemia, compliance with a blood transfusion protocol, interventions for hypotensive patients, quality of battlefield analgesia, temperature measurement and interventions, proportion of traumatic brain injury (TBI) patients with hypoxemia and/or hypotension, proportion of traumatic brain injury patients with an appropriate assessment, and proportion of missing data. Overall survival in the subset of patients with outcomes data available in the Department of Defense Trauma Registry was 97.5%. CONCLUSION: The data analyzed for this study suggest overall high compliance with established tactical combat casualty care guidelines. In the present study, nearly 7% of patients had at least one documented oxygen saturation of less than 90%, and 13% of these patients had no documentation of any intervention for hypoxemia, indicating a need for training focus on airway management for hypoxemia. Advances in battlefield analgesia continued to evolve over the period when data for this study was collected. Given the inherent high-risk, high-acuity nature of prehospital advanced life support and emphasis on the use of nonphysician practitioners in an out-of-hospital setting, the need for ongoing medical oversight and quality improvement assessment is crucial. LEVEL OF EVIDENCE: Care management, level IV.

Unrealized potential of the US military battlefield trauma system: DOW rate is higher in Iraq and Afghanistan than in Vietnam, but CFR and KIA rate are lower.

LEVEL OF EVIDENCE: Observational/retrospective/historic controls, level IV.

Advanced Resuscitative Care in Tactical Combat Casualty Care: TCCC Guidelines Change 18-01:14 October 2018.

TCCC has previously recommended interventions that can effectively prevent 4 of the top 5 causes of prehospital preventable death in combat casualties-extremity hemorrhage, junctional hemorrhage, airway obstruction, and tension pneumothorax- and deaths from these causes have been markedly reduced in US combat casualties. Noncompressible torso hemorrhage (NCTH) is the last remaining major cause of preventable death on the battlefield and often causes death within 30 minutes of wounding. Increased use of whole blood, including the capability for massive transfusion, if indicated, has the potential to increase survival in casualties with either thoracic and/or abdominopelvic hemorrhage. Additionally, Zone 1 Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) can provide temporary control of bleeding in the abdomen and pelvis and improve hemodynamics in casualties who may be approaching traumatic cardiac arrest as a result of hemorrhagic shock. Together, these two interventions are designated Advanced Resuscitative Care (ARC) and may enable casualties with severe NCTH to survive long enough to reach the care of a surgeon. Although Special Operations units are now using whole blood far-forward, this capability is not routinely present in other US combat units at this point in time. REBOA is not envisioned as care that could be accomplished by a unit medic working out of his or her aid bag. This intervention should be undertaken only by designated teams of advanced combat medical personnel with special training and equipment.

Tourniquet use on the battlefield.

This article examines the history of battlefield tourniquets. The tourniquet, if used properly, is perhaps the leading lifesaving device available to soldiers in the field. However, tourniquet use has been surrounded throughout history by controversy and dogma which continue today. Only after examining the historical context of warfare, weapons, injuries, and medical thought can we gain insight into the proper role of the tourniquet on the modern battlefield.

Tactical Study of Care Originating in the Prehospital Environment (Tacscope): Acute Traumatic Coagulopathy on the Contemporary Battlefield.

BACKGROUND: Uncontrolled major hemorrhage and delayed evacuation remain substantial contributors to potentially survivable combat death, along with mission, environment, terrain, logistics, and hostile action. Life-saving interventions and the onset of acute traumatic coagulopathy (ATC) may also contribute. OBJECTIVE: Analyze US casualty records from the DoD Trauma Registry, using International Normalized Ratio (INR) of 1.5 for onset of ATC. METHODS: Retrospective cohort study from September 2007 to June 2011, inclusive. Independent variable was INR. Primary dependent variables were transfusion volume, massive transfusion (MT) defined as >10 units RBC/fresh whole blood in first 24 h, and 30-day survival. We used T test and chi-square analysis. Our IRB reviewed and exempted this study. RESULTS: In total, 8,913 cases were available. Fifty one percent had complete data with INR. Of excluded cases, 98.9% survived, average injury severity scales (ISS) was 7 (IQR 1-8), and less than 1% received MT. Among included cases, 98.5% survived, average ISS was 10 (IQR 2-14), average INR was 1.16 (CI95 1.14-1.17), and 2.7% received MT. There were 383 cases with ATC (8.4%). After stratification, we found that ATC cases were more likely to die (odds ratio (OR) 28, CI 16-48), receive MT (OR 9.6, CI 6.4-14.4), and were acidotic (pH 7.27 (7.24-7.31) vs. 7.38 (7.38-7.39)). Other significant differences included Injury Severity Score, Revised Trauma Score, blast mechanism, and penetrating injury. CONCLUSION: ATC is substantially associated with greater injury severity, MT, and mortality. Prehospital identification of MT casualties may expedite triage and evacuation, and enable remote damage control resuscitation to delay ATC onset and improve outcomes.

Learning Curves of Emergency Tourniquet Use Exploring for Utility in Training.

BACKGROUND: Emergency tourniquet use to control hemorrhage from limb wounds is associated with improved survival and control of shock. In 2013, we introduced a way to measure learning curves of tourniquet users. With a dataset from an unrelated study, we had an opportunity to explore learning in detail. The study aim was to generate hypotheses about measurement methods in the learning of tourniquet users. METHODS: We gathered data from a previous experiment that yielded a convenient sample of repeated tourniquet applications used as a marker of learning. Data on consecutive applications on a manikin were used in the current report and were associated with two users, three models of tourniquet, and six metrics (i.e., effectiveness, pulse cessation, blood loss, time to effectiveness, windlass turn number, and pressure applied). There were 840 tests (140 tests per user, two users, three models). RESULTS: Unique characteristics of learning were associated with each user. Hypotheses generated included the following: trainee learning curves can vary in shape (e.g., flat, curved) by which metric of learning is chosen; some metrics may show much learning, whereas others show almost none; use of more than one metric may assess more comprehensively than using only one metric but may require more assessment time; number of uses required can vary by instructional goal (e.g., expertise, competence); awareness of the utility of specific metrics may vary by instructor; and some, but not all, increases in experience are associated with improved performance. CONCLUSIONS: This first-aid study generated hypotheses about caregiver learning for further study of tourniquet education and standards.

The Effect of a Golden Hour Policy on the Morbidity and Mortality of Combat Casualties.

IMPORTANCE: The term golden hour was coined to encourage urgency of trauma care. In 2009, Secretary of Defense Robert M. Gates mandated prehospital helicopter transport of critically injured combat casualties in 60 minutes or less. OBJECTIVES: To compare morbidity and mortality outcomes for casualties before vs after the mandate and for those who underwent prehospital helicopter transport in 60 minutes or less vs more than 60 minutes. DESIGN, SETTING, AND PARTICIPANTS: A retrospective descriptive analysis of battlefield data examined 21,089 US military casualties that occurred during the Afghanistan conflict from September 11, 2001, to March 31, 2014. Analysis was conducted from September 1, 2014, to January 21, 2015. MAIN OUTCOMES AND MEASURES: Data for all casualties were analyzed according to whether they occurred before or after the mandate. Detailed data for those who underwent prehospital helicopter transport were analyzed according to whether they occurred before or after the mandate and whether they occurred in 60 minutes or less vs more than 60 minutes. Casualties with minor wounds were excluded. Mortality and morbidity outcomes and treatment capability-related variables were compared. RESULTS: For the total casualty population, the percentage killed in action (16.0% [386 of 2411] vs 9.9% [964 of 9755]; P < .001) and the case fatality rate ([CFR] 13.7 [469 of 3429] vs 7.6 [1344 of 17,660]; P < .001) were higher before vs after the mandate, while the percentage died of wounds (4.1% [83 of 2025] vs 4.3% [380 of 8791]; P = .71) remained unchanged. Decline in CFR after the mandate was associated with an increasing percentage of casualties transported in 60 minutes or less (regression coefficient, -0.141; P < .001), with projected vs actual CFR equating to 359 lives saved. Among 4542 casualties (mean injury severity score, 17.3; mortality, 10.1% [457 of 4542]) with detailed data, there was a decrease in median transport time after the mandate (90 min vs 43 min; P < .001) and an increase in missions achieving prehospital helicopter transport in 60 minutes or less (24.8% [181 of 731] vs 75.2% [2867 of 3811]; P < .001). When adjusted for injury severity score and time period, the percentage killed in action was lower for those critically injured who received a blood transfusion (6.8% [40 of 589] vs 51.0% [249 of 488]; P < .001) and were transported in 60 minutes or less (25.7% [205 of 799] vs 30.2% [84 of 278]; P < .01), while the percentage died of wounds was lower among those critically injured initially treated by combat support hospitals (9.1% [48 of 530] vs 15.7% [86 of 547]; P < .01). Acute morbidity was higher among those critically injured who were transported in 60 minutes or less (36.9% [295 of 799] vs 27.3% [76 of 278]; P < .01), those severely and critically injured initially treated at combat support hospitals (severely injured, 51.1% [161 of 315] vs 33.1% [104 of 314]; P < .001; and critically injured, 39.8% [211 of 530] vs 29.3% [160 of 547]; P < .001), and casualties who received a blood transfusion (50.2% [618 of 1231] vs 3.7% [121 of 3311]; P < .001), emphasizing the need for timely advanced treatment. CONCLUSIONS AND RELEVANCE: A mandate made in 2009 by Secretary of Defense Gates reduced the time between combat injury and receiving definitive care. Prehospital transport time and treatment capability are important factors for casualty survival on the battlefield.

Use of a hemorrhage simulator to train military medics.

BACKGROUND: The leading cause of preventable battlefield death is extremity hemorrhage. This study examines how current first aid training for the management of severe extremity hemorrhage can be improved by using a patient simulator. METHODS: This was a prospective trial involving two cohorts of U.S. Army combat medic trainees. The control group received the standard first aid training for bleeding, including lectures and practical exercises. The study group received the same lectures but was exposed to a hemorrhage simulator during the practical exercises. Both groups were then evaluated during a field exercise 7 weeks later. RESULTS: The study group showed a statistically significant improvement in the time it took to stop severe extremity hemorrhage in a simulated patient. CONCLUSIONS: Simple innovations in training may play a significant role in preparing medics (and combatants) to care for injuries they will encounter on the battlefield.

Issues related to the use of tourniquets on the battlefield.

On the battlefield, a properly applied tourniquet can be an extremely effective means of controlling severe extremity wound hemorrhage. However, a great deal of confusion exists among soldiers, medics, and military medical officers on a number of tourniquet-related issues. What is an appropriate combat tourniquet? When is it appropriate to use a tourniquet? When and by whom should a tourniquet be removed? Under what conditions should a tourniquet not be released or removed? What are the most effective ways to increase limb salvage while using a tourniquet? These and other issues were addressed by a panel of experts at the 2003 Advanced Technology Applications for Combat Casualty Care Conference, August 21 and 23, 2003, St. Pete Beach, Florida. Here we review those issues and present a summary of the panel's recommendations.