Teamwork matters: The association between nontechnical skills and cardiac arrest in trauma patients presenting with hypotension.

BACKGROUND: The impact of trauma team dynamics on outcomes in injured patients is not completely understood. We sought to evaluate the association between trauma team function, as measured by a modified Trauma Non-Technical Skills assessment, and cardiac arrest in hypotensive trauma patients. We hypothesized that better team function is associated with a decreased probability of developing cardiac arrest. METHODS: Trauma video review was used to collect data from resuscitations of adult hypotensive trauma patients at 19 centers. Hypotension at emergency department presentation was defined as an initial systolic blood pressure <90 mm Hg or an initial systolic blood pressure ≥90 mm Hg followed by a systolic blood pressure <90 mm Hg within the first 5 minutes. Team dynamics were scored using a modified Trauma Non-Technical Skills assessment composed of 5 domains with combined scores ranging from 5 (best) to 15 (worst). Scores were compared between cardiac arrest/noncardiac arrest cases in the trauma bay. Logistic regression was used to evaluate the independent association between the Trauma Non-Technical Skills assessment and cardiac arrest. RESULTS: A total of 430 patients were included (median age 43 years [interquartile range: 29-61]; 71.8% male; 36% penetrating mechanism; median Injury Severity Score 20 [10-33]; 11% experienced cardiac arrest in trauma bay). The median total Trauma Non-Technical Skills assessment score was 7 (6-9), higher in patients who experienced cardiac arrest in the trauma bay (9 [6-10] vs 7 [6-9]; P = .016). This association persisted after controlling for age, sex, mechanism, injury severity, initial systolic blood pressure, and initial Glasgow Coma Scale score (adjusted odds ratio: 1.28; 95% confidence interval:1.11-1.48; P < .001), indicating a ∼3% higher predicted probability of cardiac arrest per Trauma Non-Technical Skills point. CONCLUSION: Better team function is independently associated with a decreased probability of cardiac arrest in trauma patients presenting with hypotension. This suggests that trauma team training may improve outcomes in peri-arrest patients.

Moving the needle on time to resuscitation: An EAST prospective multicenter study of vascular access in hypotensive injured patients using trauma video review.

BACKGROUND: Vascular access in hypotensive trauma patients is challenging. Little evidence exists on the time required and success rates of vascular access types. We hypothesized that intraosseous (IO) access would be faster and more successful than peripheral intravenous (PIV) and central venous catheter (CVC) access in hypotensive patients. METHODS: An EAST prospective multicenter trial was performed; 19 centers provided data. Trauma video review was used to evaluate the resuscitations of hypotensive (systolic blood pressure ≤90 mm Hg) trauma patients. Highly granular data from video recordings were abstracted. Data collected included vascular access attempt type, location, success rate, and procedural time. Demographic and injury-specific variables were obtained from the medical record. Success rates, procedural durations, and time to resuscitation were compared among access strategies (IO vs. PIV vs. CVC). RESULTS: There were 1,410 access attempts that occurred in 581 patients with a median age of 40 years (27-59 years) and an Injury Severity Score of 22 [10-34]. Nine hundred thirty-two PIV, 204 IO, and 249 CVC were attempted. Seventy percent of access attempts were successful but were significantly less likely to be successful in females (64% vs. 71%, p = 0.01). Median time to any access was 5.0 minutes (3.2-8.0 minutes). Intraosseous had higher success rates than PIV or CVC (93% vs. 67% vs. 59%, p < 0.001) and remained higher after subsequent failures (second attempt, 85% vs. 59% vs. 69%, p = 0.08; third attempt, 100% vs. 33% vs. 67%, p = 0.002). Duration varied by access type (IO, 36 [23-60] seconds; PIV, 44 [31-61] seconds; CVC 171 [105-298]seconds) and was significantly different between IO versus CVC ( p < 0.001) and PIV versus CVC ( p < 0.001) but not PIV versus IO. Time to resuscitation initiation was shorter in patients whose initial access attempt was IO, 5.8 minutes versus 6.7 minutes ( p = 0.015). This was more pronounced in patients arriving to the hospital with no established access (5.7 minutes vs. 7.5 minutes, p = 0.001). CONCLUSION: Intraosseous is as fast as PIV and more likely to be successful compared with other access strategies in hypotensive trauma patients. Patients whose initial access attempt was IO were resuscitated more expeditiously. Intraosseous access should be considered a first line therapy in hypotensive trauma patients. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level II.

Freeze-dried plasma for major trauma - Systematic review and meta-analysis.

BACKGROUND: Treatment of acute trauma coagulopathy has shifted toward rapid replacement of coagulation factors with frozen plasma (FP). There are logistic difficulties in providing FP. Freeze-dried plasma (FDP) may have logistical advantages including easier storage and rapid preparation time. This review assesses the feasibility, efficacy, and safety of FDP in trauma. STUDY DESIGN AND METHODS: Studies were searched from Medline, Embase, Cochrane Controlled Trials Register, ClinicalTrials.gov, and Google Scholar. Observational and randomized controlled trials (RCTs) assessing FDP use in trauma were included. Trauma animal models addressing FDP use were also included. Bias was assessed using validated tools. Primary outcome was efficacy, and secondary outcomes were feasibility and safety. Meta-analyses were conducted using random-effect models. Evidence was graded using Grading of Recommendations Assessment, Development, and Evaluation profile. RESULTS: Twelve human studies (RCT, 1; observational, 11) and 15 animal studies were included. Overall, studies demonstrated moderate risk of bias. Data from two studies (n = 119) were combined for meta-analyses for mortality and transfusion of allogeneic blood products (ABPs). For both outcomes, no difference was identified. For mortality, pooled odds ratio was 0.66 (95% confidence interval, 0.29-1.49), with I2 = 0%. Use of FDP is feasible, and no adverse events were reported. Animal data suggest similar results for coagulation and anti-inflammatory profiles for FP and FDP. CONCLUSION: Human data assessing FDP use in trauma report no difference in mortality and transfusion of ABPs in patients receiving FDP compared with FP. Data from animal trauma studies report no difference in coagulation factor and anti-inflammatory profiles between FP and FDP. Results should be interpreted with caution because most studies were observational and have heterogeneous population (military and civilian trauma) and a moderate risk of bias. Well-designed prospective observational studies or, preferentially, RCTs are warranted to answer FDP's effect on laboratory (coagulation factor levels), transfusion (number of ABPs), and clinical outcomes (organ dysfunction, length of stay, and mortality). LEVEL OF EVIDENCE: Systematic review and meta-analysis, level IV.

Extracorporeal membrane oxygenation use in Trauma Quality Improvement Program centers: Temporal trends and future directions.

BACKGROUND: Increased clinical experience and the decreased need for systemic anticoagulation have renewed interest in the use of extracorporeal membrane oxygenation (ECMO) for posttraumatic respiratory and cardiopulmonary failure. The objectives of this study were to describe the incidence and temporal trends of ECMO use at trauma centers, the outcomes of trauma patients undergoing ECMO, and the characteristics of trauma centers providing ECMO. METHODS: Data were derived from the American College of Surgeons Trauma Quality Improvement Program data set. We included adults with at least one severe injury admitted to a level I or II trauma center between 2012 and 2016 who received at least 1 day of mechanical ventilation. Patients were categorized based on whether or not they received ECMO during their admission. The primary outcome was change in the incidence of ECMO across study years. We also evaluated patient outcomes and variation in ECMO volumes across centers. RESULTS: Of 194,314 severely injured patients undergoing mechanical ventilation across 450 centers, 269 (0.14%) received ECMO. Extracorporeal membrane oxygenation patients had significantly higher mortality than non-ECMO patients (32% vs. 19%). The standardized rate of ECMO from 2012 to 2016 increased significantly from 75.2 to 179.0 cases per 100,000 severely injured patients undergoing mechanical ventilation. The average annual growth rate was 24%. Of the 82 centers(18%) reporting at least 1 ECMO trauma case, 34 (41%) reported only a single case. CONCLUSION: The use of ECMO for trauma, although rare, is rapidly increasing. Two thirds of patients who receive ECMO following traumatic injury survive their hospitalization. These data suggest that ECMO represents a potential treatment strategy for trauma patients with respiratory or cardiopulmonary failure. However, given the rarity of the procedure, there exists an opportunity to develop practice guidelines regarding the indications for, and approach to, ECMO in the setting of trauma. LEVEL OF EVIDENCE: Therapeutic/care management, level IV.

The University of Toronto's lasting contribution to war surgery: how Maj. L. Bruce Robertson fundamentally transformed thinking toward blood transfusion during the First World War.

SUMMARY: During the Great War, Canadian military surgeons produced some of the greatest innovations to improve survival on the battlefield. Arguably, the most important was bringing blood transfusion practice close to the edge of the battlefield to resuscitate the many casualties dying of hemorrhagic shock. Dr. L. Bruce Robertson of the Canadian Army Medical Corps was the pioneering surgeon from the University of Toronto who was able to demonstrate the benefit of blood transfusions near the front line and counter the belief that saline was the resuscitation fluid of choice in military medicine. Robertson would go on to survive the Great War, but would be taken early in life by influenza. Despite his life and career being cut short, Robertson's work is still carried on today by many military medical organizations who strive to bring blood to the wounded in austere and dangerous settings. This article has an Appendix, available at canjsurg.ca.

A comparison of live tissue training and high-fidelity patient simulator: A pilot study in battlefield trauma training.

BACKGROUND: Trauma procedural and management skills are often learned on live tissue. However, there is increasing pressure to use simulators because their fidelity improves and as ethical concerns increase. We randomized military medical technicians (medics) to training on either simulators or live tissue to learn combat casualty care skills to determine if the choice of modality was associated with differences in skill uptake. METHODS: Twenty medics were randomized to trauma training using either simulators or live tissue. Medics were trained to perform five combat casualty care tasks (surgical airway, needle decompression, tourniquet application, wound packing, and intraosseous line insertion). We measured skill uptake using a structured assessment tool. The medics also completed exit questionnaires and interviews to determine which modality they preferred. RESULTS: We found no difference between groups trained with live tissue versus simulators in how they completed each combat casualty care skill. However, we did find that the modality of assessment affected the assessment score. Finally, we found that medics preferred trauma training on live tissue because of the fidelity of tissue handling in live tissue models. However, they also felt that training on simulators also provided additional training value. CONCLUSION: We found no difference in performance between medics trained on simulators versus live tissue models. Even so, medics preferred live tissue training over simulation. However, more studies are required, and future studies need to address the measurement bias of measuring outcomes in the same model on which the study participants are trained. LEVEL OF EVIDENCE: Therapeutic/care management study, level II.

Factors affecting mortality of pediatric trauma patients encountered in Kandahar, Afghanistan.

BACKGROUND: The North Atlantic Treaty Organization (NATO) Role 3 Multinational Medical Unit (R3-MMU) is a tertiary care trauma facility that receives casualties, both coalition and civilian, and provides humanitarian medical assistance when able to the Kandahar province in southern Afghanistan. We examined the cohort of pediatric patients evaluated at the facility during a 16-month period to determine the characteristics and care requirements of this unique patient population. METHODS: A database of Afghan patients younger than 18 years of age admitted to the NATO R3-MMU between January 2010 and April 2011 was developed from the Joint Theatre Trauma Registry. This patient cohort was analyzed to determine demographics, injury mechanism, injury severity, resource utilization and factors associated with mortality. RESULTS: A total of 263 children were admitted to the NATO R3-MMU during the study period, representing 12% of all trauma admissions during this time period. The median age was 9 years (range 3 mo-17 yr) with a predominance of male patients (82%). Battle-related trauma was responsible for 62% of admissions, with explosive blast injury constituting the predominant mechanism (42%). The average injury severity score was 12.3 ± 9.3. Overall mortality was 8%. Factors associated with increased risk of death included admission acidosis, coagulopathy, hypothermia and female sex. CONCLUSION: Children represent a significant proportion of traumatic injuries encountered in a modern war zone; many of them are critically injured. Organizations that provide health care in such environments should be prepared to care for this patient population where their mandates and facilities allow for it.

CONTEXTE: L'Unité médicale multinationale de Rôle 3 (UMM R3) de l'Organisation du Traité de l'Atlantique Nord est un établissement de soins traumatologiques tertiaires qui reçoit les blessés des troupes de la coalition et de la population civile et offre une aide médicale humanitaire lorsqu'elle le peut à la population de la province de Kandahar, dans le Sud de l'Afghanistan. Nous avons étudié la cohorte de patients pédiatriques évalués à cet établissement durant une période de 16 mois afin de déterminer les caractéristiques et les besoins médicaux de cette population unique de patients. MÉTHODES: Une base de données sur les patients afghans de moins de 18 ans admis à l'UMM R3 entre janvier 2010 et avril 2011 a été établie à partir d'un registre des traumatismes liés au théâtre des opérations conjointes (Joint Theatre Trauma Registry). Cette cohorte de patients a été analysée de manière à dégager les caractéristiques démographiques, le mécanisme des traumatismes, la gravité des blessures, l'utilisation des ressources et les facteurs associés à la mortalité. RÉSULTANTS: En tout, 263 enfants ont été admis à l'UMM R3 pendant la période de l'étude, ce qui représente 12 % de toutes les admissions en traumatologie pendant cette période. L'âge médian était de 9 ans (entre 3 mois et 17 ans) et les patients étaient majoritairement de sexe masculin (82 %). Les traumatismes liés aux combats ont représenté 62 % des admissions, les blessures consécutives à une explosion en étant le mécanisme principal (42 %). Le score moyen de gravité des blessures était de 12,3 ± 9,3. La mortalité globale a été de 8 %. Les facteurs associés à un risque accru de décès incluaient l'acidose au moment de l'admission, la coagulopathie, l'hypothermie et le fait d'être de sexe féminin. CONCLUSION: Les enfants représentent une proportion significative des traumatismes rencontrés en zone de guerre, et beaucoup d'entre eux sont grièvement blessés. Les organismes qui fournissent des soins de santé dans de tels environnements devraient être prêts à soigner cette population de patients là où leur mandat et leurs installations le permettent.

The Canadian Armed Forces medical response to Typhoon Haiyan.

BACKGROUND: In the setting of international disaster response, an important challenge is determining when it is appropriate to withdraw deployed assets as the acute disaster response transitions to recovery and rebuilding. We describe our experience with realtime data collection during our medical response to Typhoon Haiyan as a means to guide military aid mission parameters. METHODS: The operational medical headquarters prospectively developed a database for use in this mission. Mobile medical teams (MMTs) were deployed to provide primary care, and the nurse designated to each MMT was responsible for entering and transmitting data daily to the medical headquarters. Data collected included the MMT location, basic patient demographics, the primary reason for the encounter and any treatment provided. These encounters were then classified as disaster, acute or chronic. RESULTS: Between Nov. 16 and Dec. 16, 2013, medical care was provided to 6596 local nationals; 238 (3.6%) had disaster-related illness or injury, 4321 (65.5%) had acute postdisaster medical conditions and 2037 (30.9%) sought medical care for chronic conditions. Of the 257 patients with traumatic injuries, 28 (11%) had disaster-related injuries and 214 (83%) had acute injuries that occurred postdisaster. CONCLUSION: The data collected during the mission to the Phillippines was compiled with performance metrics from the other Disaster Assistance Response Team components to help advise the Canadian government regarding mission duration. We recommended that data collection continue on all future missions and be modified to provide further information to larger disaster coordination teams, such as the United Nations Office for the Coordination of Humanitarian Affairs.

CONTEXTE: Dans le domaine de l'intervention internationale en cas de catastrophe, il est souvent difficile de déterminer le moment approprié pour retirer les ressources déployées alors que l'on passe de la première intervention d'urgence à la période de rétablissement et de reconstruction. Nous décrirons ici notre expérience de collecte de données en temps réel durant notre intervention médicale après le typhon Haiyan, dans le but d'orienter les paramètres de mission de l'aide militaire. MÉTHODES: Le quartier général des opérations médicales avait préparé d'avance la base de données qui a été utilisée lors de cette mission. Des équipes médicales mobiles ont été déployées pour fournir des soins de base, et une infirmière ou un infirmier désigné dans chaque équipe était chargé d'entrer et de transmettre les données quotidiennement au quartier général des opérations médicales. Les données recueillies comprenaient la position de l'équipe médicale mobile, des données démographiques de base sur les patients, la raison première de la rencontre et les traitements fournis. Ces rencontres étaient ensuite classées comme catastrophiques, aiguës ou chroniques. RÉSULTANTS: Du 16 novembre au 16 décembre 2013, des soins médicaux ont été prodigués à 6596 Philippins; 238 personnes (3,6 %) avaient des maladies ou des blessures liées au typhon, 4321 personnes (65,5 %) avaient des problèmes médicaux aigus d'après catastrophe et 2037 personnes (30,9 %) avaient besoin de soins pour des affections chroniques. Des 257 patients ayant subi des lésions traumatiques, 28 (11 %) avaient des blessures liées à la catastrophe et 214 (83 %) avaient des blessures aiguës reçues après la catastrophe. CONCLUSION: Les données recueillies durant la mission aux Philippines ont été compilées avec les indicateurs de rendement des autres composantes de l'équipe d'intervention en cas de catastrophe pour conseiller le gouvernement canadien au sujet de la durée des missions. Nous recommandons que la collecte de données se poursuive durant toutes les missions futures et soit modifiée afin de fournir plus de renseignements aux plus grandes équipes de coordination des interventions en cas de catastrophe, comme le Bureau de la coordination des affaires humanitaires de l'Organisation des Nations Unies.

Acute nontraumatic general surgical conditions on a combat deployment.

BACKGROUND: Literature is lacking on acute surgical problems that may be encountered on military deployment; even less has been written on whether or not any of these surgical problems could have been avoided with more focused predeployment screening. We sought to determine the burden of illness attributable to acute nontraumatic general surgical problems while on deployment and to identify areas where more rigorous predeployment screening could be implemented to decrease surgical resource use for nontraumatic problems. METHODS: We studied all Canadian Armed Forces (CAF) members deployed to Afghanistan between Feb. 7, 2006, and June 30, 2011, who required treatment for a nontraumatic general surgical condition. RESULTS: During the study period 28 990 CAF personnel deployed to Afghanistan; 373 (1.28%) were repatriated because of disease and 100 (0.34%) developed an acute general surgical condition. Among those who developed an acute surgical illness, 42 were combat personnel (42%) and 58 were support personnel (58%). Urologic diagnoses (n = 34) were the most frequent acute surgical conditions, followed by acute appendicitis (n = 18) and hernias (n = 12). We identified 5 areas where intensified predeployment screening could have potentially decreased the incidence of in-theatre acute surgical illness. CONCLUSION: Our findings suggest that there is a significant acute care surgery element encountered on combat deployment, and surgeons tasked with caring for this population should be prepared to treat these patients.

CONTEXTE: Il y a un manque de données sur les problèmes chirurgicaux aigus qui peuvent survenir lors de déploiements militaires, et encore moins sur la question de savoir si on aurait pu éviter ces problèmes en faisant un dépistage plus ciblé avant le déploiement. Nous avons tenté de déterminer le fardeau de la maladie attribuable à des problèmes non traumatiques aigus de chirurgie générale pendant le déploiement, puis d'identifier les domaines où un dépistage préalable plus rigoureux pourrait être mis en oeuvre pour réduire l'utilisation des ressources chirurgicales pour les problèmes non traumatiques. MÉTHODES: Notre étude a porté sur tous les membres des Forces armées canadiennes (FAC) déployés en Afghanistan entre le 7 février 2006 et le 30 juin 2011 et qui ont eu besoin de traitement pour un état chirurgical général non traumatique. RÉSULTANTS: Pendant la période de l'étude, 28 990 membres des FAC ont été déployés en Afghanistan; 373 (1,28 %) ont été rapatriés en raison de maladie et 100 (0,34 %) ont développé un état chirurgical général aigu. Parmi ces derniers, 42 faisaient partie du personnel de combat (42 %) et 58 faisaient partie du personnel de soutien (58 %). Les diagnostics urologiques (n = 34) constituaient les états chirurgicaux aigus les plus fréquents, suivis de l'appendicite aiguë (n = 18) et des hernies (n = 12). Nous avons identifié 5 domaines où un dépistage intensifié, préalable au déploiement, aurait possiblement réduit l'incidence des états chirurgicaux aigus en théâtre d'opérations. CONCLUSION: Il ressort de nos conclusions que les missions de combat comportent un important élément de soins chirurgicaux aigus et que les chirurgiens chargés de soigner cette population devraient être préparés à traiter ces patients.

Advances in damage control resuscitation and surgery: implications on the organization of future military field forces.

Medical support to deployed field forces is increasingly becoming a shared responsibility among allied nations. National military medical planners face several key challenges, including fiscal restraints, raised expectations of standards of care in the field and a shortage of appropriately trained specialists. Even so, medical services are now in high demand, and the availability of medical support may become the limiting factor that determines how and where combat units can deploy. The influence of medical factors on operational decisions is therefore leading to an increasing requirement for multinational medical solutions. Nations must agree on the common standards that govern the care of the wounded. These standards will always need to take into account increased public expectations regarding the quality of care. The purpose of this article is to both review North Atlantic Treaty Organization (NATO) policies that govern multinational medical missions and to discuss how recent scientific advances in prehospital battlefield care, damage control resuscitation and damage control surgery may inform how countries within NATO choose to organize and deploy their field forces in the future.

De plus en plus, la responsabilité du soutien médical offert aux forces militaires déployées sur le terrain devient partagée entre les nations alliées. Les planificateurs médicaux militaires nationaux font face à plusieurs défis importants, tels que restrictions budgétaires, attentes élevées au chapitre des normes de soin sur le terrain et pénurie de spécialistes dûment formés. Malgré cela, les services médicaux sont présentement en grande demande et leur disponibilité pourrait devenir le facteur limitatif susceptible de déterminer de quelle façon et en quels lieux les unités de combat peuvent se déployer. L'impact des facteurs médicaux sur les décisions opérationnelles requiert donc de plus en plus des solutions médicales multinationales. Les nations doivent s'entendre sur des normes communes qui régissent les soins à prodiguer aux blessés. Ces normes devront toujours tenir compte des attentes accrues du public en regard de la qualité des soins. Le but de cet article est de revoir les politiques de l'Organisation du Traité de l'Atlantique Nord (OTAN) qui régissent les missions médicales multinationales et de discuter de la façon dont les progrès scientifiques récents des soins pré-hospitaliers sur les champs de bataille et les techniques de réanimation et de chirurgie de sauvetage peuvent éclairer la façon dont les pays de l'OTAN décideront d'organiser et de déployer leurs forces sur le terrain à l'avenir.

Spinal injuries after improvised explosive device incidents: implications for Tactical Combat Casualty Care.

BACKGROUND: Tactical Combat Casualty Care aims to treat preventable causes of death on the battlefield but deemphasizes the importance of spinal immobilization in the prehospital tactical setting. However, improvised explosive devices (IEDs) now cause the majority of injuries to Canadian Forces (CF) members serving in Afghanistan. We hypothesize that IEDs are more frequently associated with spinal injuries than non-IED injuries and that spinal precautions are not being routinely employed on the battlefield. METHODS: We examined retrospectively a database of all CF soldiers who were wounded and arrived alive at the Role 3 Multinational Medical Unit in Kandahar, Afghanistan, from February 7, 2006, to October 14, 2009. We collected data on demographics, injury mechanism, anatomic injury descriptions, physiologic data on presentation, and prehospital interventions performed. Outcomes were incidence of any spinal injuries. RESULTS: Three hundred seventy-two CF soldiers were injured during the study period and met study criteria. Twenty-nine (8%) had spinal fractures identified. Of these, 41% (n = 12) were unstable, 31% (n = 9) stable, and 28% indeterminate. Most patients were injured by IEDs (n = 212, 57%). Patients injured by IEDs were more likely to have spinal injuries than those injured by non-IED-related mechanisms (10.4% vs. 2.3%; p < 0.01). IED victims were even more likely to have spinal injuries than patients suffering blunt trauma (10.4% vs. 6.7%; p = 0.02). Prehospital providers were less likely to immobilize the spine in IED victims compared with blunt trauma patients (10% [22 of 212] vs. 23.0% [17 of 74]; p < 0.05). CONCLUSIONS: IEDs are a common cause of stable and unstable spinal injuries in the Afghanistan conflict. Spinal immobilization is an underutilized intervention in the battlefield care of casualties in the conflict in Afghanistan. This may be a result of tactical limitations; however, current protocols should continue to emphasize the judicious use of immobilization in these patients.

Tactical combat casualty care in the Canadian Forces: lessons learned from the Afghan war.

Tactical Combat Casualty Care (TCCC) is intended to treat potentially preventable causes of death on the battlefield, but acknowledges that application of these treatments may place the provider and even the mission in jeopardy if performed at the wrong time. Therefore, TCCC classifies the tactical situation with respect to health care provision into 3 phases (care under fire, tactical field care and tactical evacuation) and only permits certain interventions to be performed in specific phases based on the danger to the provider and casualty. In the 6 years that the Canadian Forces (CF) have been involved in sustained combat operations in Kandahar, Afghanistan, more than 1000 CF members have been injured and more than 150 have been killed. As a result, the CF gained substantial experience delivering TCCC to wounded soldiers on the battlefield. The purpose of this paper is to review the principles of TCCC and some of the lessons learned about battlefield trauma care during this conflict.

A vertebrate Polycomb response element governs segmentation of the posterior hindbrain.

Chromatin remodeling by Polycomb group (PcG) and trithorax group (trxG) proteins regulates gene expression in all metazoans. Two major complexes, Polycomb repressive complexes 1 and 2 (PRC1 and PRC2), are thought to mediate PcG-dependent repression in flies and mammals. In Drosophila, PcG/trxG protein complexes are recruited by PcG/trxG response elements (PREs). However, it has been unclear how PcG/trxG are recruited in vertebrates. Here we have identified a vertebrate PRE, PRE-kr, that regulates expression of the mouse MafB/Kreisler gene. PRE-kr recruits PcG proteins in flies and mouse F9 cells and represses gene expression in a PcG/trxG-dependent manner. PRC1 and 2 bind to a minimal PRE-kr region, which can recruit stable PRC1 binding but only weak PRC2 binding when introduced ectopically, suggesting that PRC1 and 2 have different binding requirements. Thus, we provide evidence that similar to invertebrates, PREs act as entry sites for PcG/trxG chromatin remodeling in vertebrates.

Retrovirus silencer blocking by the cHS4 insulator is CTCF independent.

Silencing of retrovirus vectors poses a significant obstacle to genetic manipulation of stem cells and their use in gene therapy. We describe a mammalian silencer blocking assay using insulator elements positioned between retrovirus silencer elements and an LCRbeta-globin reporter transgene. In transgenic mice, we show that retrovirus silencers are blocked by the cHS4 insulator. Silencer blocking is independent of the CTCF binding site and is most effective when flanking the internal reporter transgene. These data distinguish silencer blocking activity by cHS4 from its enhancer blocking activity. Retrovirus vectors can be created at high titer with one but not two internal dimer cHS4 cores. cHS4 in the LTRs has no effect on expression in transduced F9 cells, suggesting that position effect blocking is not sufficient to escape silencing. The Drosophila insulators gypsy and Scs fail to block silencing in transgenic mice, but gypsy stimulates vector expression 2-fold when located in the LTRs of an infectious retrovirus. The silencer blocking assay complements existing insulator assays in mammalian cells, provides new insight into mechanisms of insulation and is a valuable tool to identify additional silencer blocking insulators that cooperate with cHS4 to improve stem cell retrovirus vector design.