Chronic critical illness after hypothermia in trauma patients

Objectives

Chronic critical illness (CCI) is a phenotype that occurs frequently in patients with severe injury. Previous work has suggested that inflammatory changes leading to CCI occur early following injury. However, the modifiable factors associated with CCI are unknown. We hypothesized that hypothermia, an early modifiable factor, is associated with CCI.

Methods

To determine the association of hypothermia and CCI, a secondary analysis of the Inflammation and Host Response to Injury database was performed, and subsequently validated on a similar cohort of patients from a single level 1 trauma center from January 2015 to December 2019. Hypothermia was defined as initial body temperature ≤34.5°C. CCI was defined as death or sustained multiorgan failure ≥14 days after injury. Data were analyzed using univariable analyses with Student’s t-test and Pearson’s χ² test, and logistic regression. An arrayed genomic analysis of the transcriptome of circulating immune cells was performed in these patients.

Results

Of the initial 1675 patients, 254 had hypothermia and 1421 did not. On univariable analysis, 120/254 (47.2%) of patients with hypothermia had CCI, compared with 520/1421 (36.6%) without hypothermia who had CCI, p<0.001. On multivariable logistic regression, hypothermia was independently associated with CCI, OR 1.61 (95% CI 1.17 to 2.21) but not mortality. Subsequent validation in 1264 patients of which 172 (13.6%) were hypothermic, verified that hypothermia was independently associated with CCI on multivariable logistic regression, OR 1.84 (95% CI 1.21 to 2.41). Transcriptomic analysis in hypothermic and non-hypothermic patients revealed unique cellular-specific genomic changes to only circulating monocytes, without any distinct effect on neutrophils or lymphocytes.

Conclusions

Hypothermia is associated with the development of CCI in severely injured patients. There are transcriptomic changes which indicate that the changes induced by hypothermia may be associated with persistent CCI. Thus, early reversal of hypothermia following injury may prevent the CCI.

Level of evidence

III.

Is the "Death Triad" a Casualty of Modern Damage Control Resuscitation

BACKGROUND

Principles of damage control laparotomy (DCL) focus on early surgical control of hemorrhage and contamination in addition to damage control resuscitation (DCR) to combat the significant mortality associated with the "death triad" of hypothermia, acidosis, and coagulopathy. We hypothesized that DCL patients managed with DCR would have lower mortality from the death triad than historical studies.

METHODS

A 5-y retrospective chart review of all consecutive adult trauma patients presenting to a Level I trauma center who underwent DCL was conducted. Parameters associated with the death triad were evaluated on admission and 24 h after the presentation. Kaplan Meier survival plots were used to compare the components of the death triad. Univariate and multivariate analyses were performed.

RESULTS

A total of 149 adult patients were identified. The overall incidence of death triad was 20.8% (n = 31/149). 24-h mortality for all patients was 5.4% (n = 8/149). Kaplan Meier plots showed that 24-h mortality was significantly increased if 3/3 components of the death triad were present (P < 0.05). At 24-h after admission, mortality occurred in 16.6% (n = 5/30) of patients with the death triad.

CONCLUSIONS

This study confirms that the 24-h mortality of trauma patients increased with the addition of all three death triad components. The death triad predicted death in 16.6% of patients treated with DCL and DCR at 24 h. Results suggest that the death triad might not be as applicable in the modern era of DCL in combination with DCR. Other factors contributing to in-hospital mortality need to be further elucidated.

Clinical evaluation of whole blood prothrombin time (PT) and international normalized ratio (INR) using a Laser Speckle Rheology sensor

Prothrombin time (PT) and the associated international normalized ratio (INR) are routinely tested to assess the risk of bleeding or thrombosis and to monitor response to anticoagulant therapy in patients. To measure PT/INR, conventional coagulation testing (CCT) is performed, which is time-consuming and requires the separation of cellular components from whole blood. Here, we report on a portable and battery-operated optical sensor that can rapidly quantify PT/INR within seconds by measuring alterations in the viscoelastic properties of a drop of whole blood following activation of coagulation with thromboplastin. In this study, PT/INR values were measured in 60 patients using the optical sensor and compared with the corresponding CCT values. Our results report a close correlation and high concordance between PT/INR measured using the two approaches. These findings confirm the accuracy of our optical sensing approach for rapid PT/INR testing in whole blood and highlight the potential for use at the point-of-care or for patient self-testing.

Predictors of massive blood transfusion: a Delphi Study to examine the views of experts

BACKGROUND

Trauma patients requiring massive blood transfusion (MBT) have high morbidity and mortality: early and aggressive use of blood products during immediate resuscitation may improve survival. There is currently a lack of evidence to guide initial identification of these patients which is especially important in areas where plasma may need to be thawed. In the absence of this evidence, this study aimed to robustly evaluate expert opinion by using a Delphi process to identify predictors of massive transfusion. This process can be used to ensure that decision rules include variables that have clinical validity, which may improve translation of rules into clinical practice.

METHODS

An international panel of 35 experts was identified through expert advice against specific criteria. Military and civilian experts from the fields of emergency medicine, critical care, anaesthesia, prehospital care, haematology and general/trauma surgery were included. The Delphi Study was carried out over three rounds. Consensus level was predefined at 80%.

RESULTS

195 statements were generated by the panel of which 97 (49.7%) achieved consensus at the 80% level by the end of round 3. Strikingly no clinical observations reached consensus individually. Metabolic acidosis of a base excess of -5.0 or worse, lactate >5 mmol/L and a low haematocrit on arrival were all considered predictive. Some patterns of injury, but few mechanisms of injury, were considered highly predictive of the need of MBT.

CONCLUSIONS

This Delphi process has produced a list of parameters that expert clinicians felt were predictive for MBT. This list can be used to inform the generation of decision rules. It is of note that many factors used in current decision rules were not valued by clinical experts-this may be a cause for poor uptake of those rules.

Evolving beyond the vicious triad: Differential mediation of traumatic coagulopathy by injury, shock, and resuscitation

BACKGROUND

A subset of trauma patients with critical injury present with coagulopathy, portending markedly worse outcomes. Clinical practice is evolving to treat the classical risk factors of hypothermia, hemodilution, and acidosis; however, coagulopathy persists even in the absence of these factors. We sought to determine the relative importance of injury- and shock-specific factors compared with resuscitation-associated factors in coagulopathy after trauma.

METHODS

Comprehensive demographic data, laboratory data, and outcomes data were prospectively collected from seven trauma centers over 8 years (November 2003 to August 2011) as part of the Inflammation and the Host Response to Injury Large-Scale Collaborative Program. A total of 1,537 critically injured patients with blunt trauma and hemorrhagic shock were analyzed to evaluate predictors of admission coagulopathy (international normalized ratio [INR] ≥ 1.3), multiorgan failure, and mortality.

RESULTS

Of 1,537 patients, 578 (37.6%) had admission INR of 1.3 or greater. Coagulopathic patients had more severe injury, more severe base deficit and lactate levels, as well as lower admission temperature, lower pH, and higher prehospital crystalloid volume (all p < 0.001). Coagulopathic patients required more blood products and mechanical ventilation and had higher rates of nosocomial infection, multiorgan failure, and mortality (all p < 0.02). Injury severity, temperature, and acidosis (all p < 0.02) independently predicted coagulopathy in multivariate analysis, with a significant interaction between lactate and prehospital crystalloid. In Cox regression models, however, coagulopathy itself remained an independent predictor of both multiorgan failure and mortality (p < 0.02) even when adjusted for injury severity, shock, and elements of the vicious triad.

CONCLUSION

Most patients with coagulopathy after trauma have mixed risk factors; however, coagulopathy has deleterious effects independent of injury severity, shock, and the vicious triad. Better understanding of the biochemical mechanisms of acute traumatic coagulopathy may facilitate biochemically targeted resuscitation strategies and improve outcomes.

LEVEL OF EVIDENCE

Prognostic and epidemiologic study, level II.

Coagulopathy after severe pediatric trauma

Trauma remains the leading cause of morbidity and mortality in the United States among children aged 1 to 21 years. The most common cause of lethality in pediatric trauma is traumatic brain injury. Early coagulopathy has been commonly observed after severe trauma and is usually associated with severe hemorrhage and/or traumatic brain injury. In contrast to adult patients, massive bleeding is less common after pediatric trauma. The classical drivers of trauma-induced coagulopathy include hypothermia, acidosis, hemodilution, and consumption of coagulation factors secondary to local activation of the coagulation system after severe traumatic injury. Furthermore, there is also recent evidence for a distinct mechanism of trauma-induced coagulopathy that involves the activation of the anticoagulant protein C pathway. Whether this new mechanism of posttraumatic coagulopathy plays a role in children is still unknown. The goal of this review is to summarize the current knowledge on the incidence and potential mechanisms of coagulopathy after pediatric trauma and the role of rapid diagnostic tests for early identification of coagulopathy. Finally, we discuss different options for treating coagulopathy after severe pediatric trauma.

Assessing blood coagulation status with laser speckle rheology

We have developed and investigated a novel optical approach, Laser Speckle Rheology (LSR), to evaluate a patient's coagulation status by measuring the viscoelastic properties of blood during coagulation. In LSR, a blood sample is illuminated with laser light and temporal speckle intensity fluctuations are measured using a high-speed CMOS camera. During blood coagulation, changes in the viscoelastic properties of the clot restrict Brownian displacements of light scattering centers within the sample, altering the rate of speckle intensity fluctuations. As a result, blood coagulation status can be measured by relating the time scale of speckle intensity fluctuations with clinically relevant coagulation metrics including clotting time and fibrinogen content. Our results report a close correlation between coagulation metrics measured using LSR and conventional coagulation results of activated partial thromboplastin time, prothrombin time and functional fibrinogen levels, creating the unique opportunity to evaluate a patient's coagulation status in real-time at the point of care.

Medical aspects of terrorist bombings - a focus on DCS and DCR

Although terrorist bombings have tormented the world for a long time, currently they have reached unprecedented levels and become a continuous threat without borders, race or age. Almost all of them are caused by improvised explosive devices. The unpredictability of the terrorist bombings, leading to simultaneous generation of a large number of casualties and severe "multidimensional" blast trauma require a constant vigilance and preparedness of every hospital worldwide. Approximately 1-2.6% of all trauma patients and 7% of the combat casualties require a massive blood transfusion. Coagulopathy is presented in 65% of them with mortality exceeding 50%. Damage control resuscitation is a novel approach, developed in the military practice for treatment of this subgroup of trauma patients. The comparison with the conventional approach revealed mortality reduction with 40-74%, lower frequency of abdominal compartment syndrome (8% vs. 16%), sepsis (9% vs. 20%), multiorgan failure (16% vs. 37%) and a significant reduction of resuscitation volumes, both crystalloids and blood products. DCS and DCR are promising new approaches, contributing for the mortality reduction among the most severely wounded patients. Despite the lack of consensus about the optimal ratio of the blood products and the possible influence of the survival bias, we think that DCR carries survival benefit and recommend it in trauma patients with exsanguinating bleeding.

Acute coagulopathy of trauma in the rat

INTRODUCTION

Acute coagulopathy of trauma (aCOT) is a state of disordered coagulation developing soon after severe injury and blood loss and has been defined in the clinical literature as an elevation in prothrombin time (PT) and activated partial thromboplastin time (aPTT).

OBJECTIVE

The purpose of this study was to develop a rat model of aCOT resulting from polytrauma and hemorrhage and showing an elevation in PT and aPTT.

METHODS

Sprague-Dawley rats (300-400 g) were anesthetized with isoflurane. Polytrauma was induced by damaging 10 cm of small intestines, the right and medial liver lobes, the right leg skeletal muscle, and fracture of the right femur. Rats were hemorrhaged 40% of their estimated blood volume. No resuscitation was given. Venous and arterial blood samples were taken at times up to 4 h.

RESULTS

Polytrauma and hemorrhage resulted in a significant rise in PT, aPTT, potassium, lactate, and glucose. There was a significant decrease in plasma bicarbonate, base excess, and sodium. Blood urea nitrogen and creatinine rose steadily throughout the 4 h indicative of progressive renal failure. Hematocrit decreased significantly immediately after hemorrhage and trauma indicating a movement of fluid into the vascular space from extravascular sources, which was mirrored by a decrease in plasma fibrinogen concentration. In contrast, platelet count initially decreased, rose at 2 h, and decreased again at 3 to 4 h, indicating that platelets were released into the vascular space. The change in platelet count was mirrored by the changes in thrombin-antithrombin and plasmin-antiplasmin complexes. Rotational thromboelastometry showed complex changes. Clotting firmness fell initially, rose at 2 h, and fell again at 3 to 4 h similar to the changes in platelet count. α Angle was elevated, and clotting time was shortened over the 4 h. Treatment with cytochalasin D (platelet function inhibitor) eliminated the increases in clotting firmness and thrombin generation seen at 2 h with rising platelet count.

CONCLUSIONS

This model of aCOT in rats showed complex changes in clotting parameters over 4 h that included a rise in PT and aPTT. At 4 h, there was a decrease in clotting firmness, even though the clot formation was faster (elevated α angle and decrease in clotting time). The decrease in clotting firmness correlated with falling fibrinogen and platelet count. This model affords an opportunity to evaluate interventions in the treatment of aCOT.

The impact of blood product ratios in massively transfused pediatric trauma patients

BACKGROUND

Few studies have examined the impact of balanced resuscitation in pediatric trauma patients requiring massive transfusions. Adult data may not be generalizable to children.

METHODS

Retrospective analysis assessed patients seen at a level I trauma center between 2003 and 2010 aged ≤18 years requiring massive packed red blood cell (PRBC) transfusion, defined as transfusion of ≥50% total blood volume. After excluding mortalities in the first 24 hours, the impact of plasma and platelet ratios on mortality was evaluated.

RESULTS

Of 6,675 pediatric trauma patients, 105 were massively transfused (mean age, 12.4 ± 6.3 years; mean Injury Severity Score, 25.8 ± 11.4; mortality rate, 18.1%). All deceased patients sustained severe head injuries. Plasma/PRBC and platelet/PRBC ratios were not significantly associated with mortality.

CONCLUSIONS

In this study, higher plasma/PRBC and platelet/PRBC ratios were not associated with increased survival in children. The value of aggressive blood product transfusion for injured pediatric patients requires further prospective validation.

A principal component analysis of coagulation after trauma

BACKGROUND

Clotting factor abnormalities underlying acute traumatic coagulopathy are poorly understood, with application of traditional regression techniques confounded by colinearity. We hypothesized that principal components analysis (PCA), a pattern-finding and data reduction technique, would identify clinically predictive patterns in the complex clotting factor milieu after trauma.

METHODS

Plasma was prospectively collected from 163 critically injured trauma patients. Prothrombin; factors V, VII, VIII, IX, X; D-dimer; activated and native protein C; and antithrombin III levels were assayed and subjected to nonlinear PCA to identify principal components (PCs).

RESULTS

Of 163 patients, 19.0% were coagulopathic on admission. PCA identified 3 significant PCs, accounting for 67.5% of overall variance. PC1 identified global clotting factor depletion; PC2 the activation of protein C and fibrinolysis; and PC3 factor VII elevation and VIII depletion. PC1 score correlated with penetrating injury and injury severity, predicting coagulopathy (odds ratio [OR], 4.67; p < 0.001) and mortality (OR, 1.47; p = 0.032). PC2 score correlated with injury severity, acidosis, and shock, and significantly predicted ventilator-associated pneumonia (OR, 1.59; p = 0.008), acute lung injury (OR, 2.24; p < 0.001), multiorgan failure (OR, 1.83; p = 0.002), and mortality (OR, 1.62; p = 0.006) but was not associated with international normalized ratio (INR)-based or partial thromboplastin time (PTT)-based coagulopathy (p > 0.200). PC3 did not significantly predict outcomes.

CONCLUSION

PCA identifies distinct patterns of coagulopathy: depletion coagulopathy predicts mortality and INR/PTT elevation, while fibrinolytic coagulopathy predicts infection, end-organ failure, and mortality, without detectable differences in INR or PTT. While depletion coagulopathy is intuitive, fibrinolytic coagulopathy may be a distinct but often overlapping entity with differential effects on outcomes.

New strategies for massive transfusion in the bleeding trauma patient

Trauma continues to be the leading cause of death among those younger than 40 years. A major cause of death within the first 24 hours is hemorrhage. Many of these patients present with severe coagulopathy and require massive transfusion. Earlier control of coagulopathy has been shown to improve survival. To address coagulopathy sooner, changes in the way we identify and resuscitate the exsanguinating trauma patient have evolved. These changes include early identification of at-risk patients and early, aggressive transfusion of plasma and platelets. This article reviews the key massive transfusion triggers and resuscitation strategy of damage control resuscitation.

Glasgow Coma Scale as a predictor for hemocoagulative disorders after blunt pediatric traumatic brain injury

OBJECTIVE

Coagulopathy is a complication of traumatic brain injury and its presence after injury has been identified as a risk factor for prognosis. It was our aim to determine whether neurologic findings reflected by Glasgow Coma Scale at initial resuscitation can predict hemocoagulative disorders resulting from traumatic brain injury that may aggravate clinical sequelae and outcome in children.

DESIGN

A retrospective analysis of 200 datasets from children with blunt, isolated traumatic brain injury documented in the Trauma Registry of the Deutsche Gesellschaft für Unfallchirurgie was conducted. Inclusion criteria were primary admission, age <14 yrs, and sustained isolated blunt traumatic brain injury.

SETTING

Trauma Registry of the Deutsche Gesellschaft für Unfallchirurgie-affiliated trauma centers in Germany.

PATIENTS

: Two hundred datasets of children (age <14 yrs) with blunt isolated traumatic brain injury were analyzed: children were subdivided into two groups according to Glasgow Coma Scale at the scene (Glasgow Coma Scale ≤ 8 vs. Glasgow Coma Scale >8) and reviewed for coagulation abnormalities upon emergency room admission and outcome.

MEASUREMENT AND MAIN RESULTS

Fifty-one percent (n = 102 of 200) of children had Glasgow Coma Scale >8 and 49% (n = 98 of 200) had Glasgow Coma Scale ≤ 8 at the scene. The incidence of coagulopathy at admission was higher in children with Glasgow Coma Scale ≤ 8 compared to children with Glasgow Coma Scale >8: 44% (n = 31 of 71) vs. 14% (n = 11 of 79) (p < .001). Multivariate logistic regression revealed that Glasgow Coma Scale ≤ 8 at scene was associated with coagulopathy at admission (odds ratio 3.378, p = .009) and stepwise regression identified Glasgow Coma Scale ≤ 8 as an independent risk factor for coagulopathy. Mortality in children with Glasgow Coma Scale ≤ 8 at scene was substantially higher with the presence of coagulation abnormalities at admission compared to children in which coagulopathy was absent (51.6%, n = 16 of 31 vs. 5% n = 2 of 40).

CONCLUSIONS

Glasgow Coma Scale ≤ 8 at scene in children with isolated traumatic brain injury is associated with increased risk for coagulopathy and mortality. These results may guide laboratory testing, management, and blood bank resources in acute pediatric trauma care.

Crystalloid to packed red blood cell transfusion ratio in the massively transfused patient: when a little goes a long way

BACKGROUND

Massive transfusion (MT) protocols have emphasized the importance of ratio-based transfusion of plasma and platelets relative to packed red blood cells (PRBCs); however, the risks attributable to crystalloid resuscitation in patients requiring MT remain largely unexplored. We hypothesized that an increased crystalloid:PRBC (C:PRBC) ratio would be associated with increased morbidity and poor outcome after MT.

METHODS

Data were obtained from a multicenter prospective cohort study evaluating outcomes in blunt injured adults with hemorrhagic shock. Patients requiring MT (≥ 10 units PRBCs in first 24 hours) were analyzed. The C:PRBC ratio was computed by the ratio of crystalloid infused in liters (L) to the units of PRBCs transfused in the first 24 hours postinjury. Logistic regression modeling was used to characterize the independent risks associated with the 24-hour C:PRBC ratio, after controlling for important confounders and other blood component transfusion requirements.

RESULTS

Logistic regression revealed that the 24-hour C:PRBC ratio was significantly associated with a greater independent risk of multiple organ failure (MOF), acute respiratory distress syndrome (ARDS), and abdominal compartment syndrome (ACS). No association with mortality or nosocomial infection was found. A dose-response analysis revealed that patients with a C:PRBC ratio >1.5:1 had over a 70% higher independent risk of MOF and over a twofold higher risk of ARDS and ACS.

CONCLUSION

In patients requiring MT, crystalloid resuscitation in a ratio greater than 1.5:1 per unit of PRBCs transfused was independently associated with a higher risk of MOF, ARDS, and ACS. These results suggest overly aggressive crystalloid resuscitation should be minimized in these severely injured patients. Further research is required to determine whether incorporation of the C:PRBC ratio into MT protocols improves outcome.

Polytrauma – new horizons for management

The management of polytrauma has evolved considerably in the last century. Advances have been made in all disciplines involved in trauma care from pre-hospital care and resuscitation protocols to diagnostics, surgical techniques, administration of novel pharmacological agents and late reconstruction procedures. Improved understanding of the altered physiology and the induced response at the molecular level offers the potential for novel management strategies and prevention of post-traumatic complications.

Critical care issues in managing complex open abdominal wound

Over the past 30 years, surgical specialties have introduced and expanded the role of open abdominal management in complicated operative cases, necessitating an intensivist's understanding of the indications and unique intensive care unit (ICU) issues related to the open abdomen. When presented with the open abdomen, resuscitation to correct shock is of primary concern. This is accomplished by correction of hypothermia, acidosis, and coagulopathy in trauma and adequate resolution of intra-abdominal hypertension or source control in general surgery. These patients typically require deep sedation and often paralysis and benefit from low-volume ventilatory strategies to prevent and treat acute lung injury. Antibiotics must be tailored to the clinical situation, but in most cases, 24 hours of perioperative treatment is all that is required. In cases of gross contamination and peritonitis, a 5- to 7-day course of broad-spectrum antibiotics may be of benefit.Adequate source control has been demonstrated to have the greatest impact on outcome and when the patient's clinical milieu dictates, bedside washouts. Enteral nutrition should be instituted as early as possible after intestinal continuity has been reestablished. Additional protein is required to account for losses from the open abdomen. Reconstruction may require staging, but in general, should proceed following resolution of shock and control of sepsis. Elevated multiorgan dysfunction score, Acute Physiology And Chronic Health Evaluation II (APACHE II), and a rise in peak inspiratory pressure portend poor source control and could result in failure of fascial closure. If unable to proceed to fascial closure, then considerations should be made for planned ventral hernia and subsequent abdominal wall reconstruction.

Damage Control Resuscitation: From Emergency Department to the Operating Room

Damage control surgery emphasizes limited operations with control of bleeding and contamination. Traditional management centered upon correction of acidosis and hypotension with crystalloids. Damage control resuscitation (DCR) is permissive hypotension and early hemostatic resuscitation combined identified and corrects coagulopathy with fresh-frozen plasma (FFP), restricting use of crystalloids. We hypothesize a survival advantage in patients managed with DCR when compared with a historical cohort of patients. During the 2-year retrospective review, a 1-year period after institution of DCR was compared with a historical control. Resuscitation strategies were analyzed and stratified into emergency department (ED) resuscitation and intraoperative resuscitation. Univariate analysis of continuous data was done with Student's t test followed by multiple logistic regression. Fifty-seven and 61 patients were managed during the Non DCR and DCR periods respectively. Baseline demographic patient characteristics and physiologic variables were similar between groups. ED DCR patients received less crystalloids: 1.1 versus 4.7 liters ( P = 0.0001), more FFP: 1.8 versus 0.5 ( P = 0.001). NonDCR had a lower initial systolic pressure in the operating room when compared with DCR: 81 mm Hg versus 95 mm Hg ( P = 0.03). DCR patients received less intraoperative crystalloids: 5.7 versus 15.8 liters ( P = 0.0001) and more FFP: 15.1 versus 6.2 ( P = 0.0001). DCR conveyed a survival benefit (Odds Ratio; 95% confidence interval: 0.40 (0.18-0.90), P = 0.024). NonDCR group had 13.2 days longer hospital length of stay. Damage control resuscitation, beginning in the ED, used more packed red blood cells and FFP minimizing crystalloids. DCR was associated with a survival advantage and shorter length of stay in patients with severe hemorrhage.

Improvised explosive devices: pathophysiology, injury profiles and current medical management

The improvised explosive device (IED), in all its forms, has become the most significant threat to troops operating in Afghanistan and Iraq. These devices range from rudimentary home made explosives to sophisticated weapon systems containing high-grade explosives. Within this broad definition they may be classified as roadside explosives and blast mines, explosive formed pojectile (EFP) devices and suicide bombings. Each of these groups causeinjury through a number of different mechanisms and can result in vastly different injury profiles. The "Global War on Terror" has meant that incidents which were previously exclusively seen in conflict areas, can occur anywhere, and clinicians who are involved in emergency trauma care may be required to manage casualties from similar terrorist attacks. An understanding of the types of devices and their pathophysiological effects is necessary to allow proper planning of mass casualty events and to allow appropriate management of the complex poly-trauma casualties they invariably cause. The aim of this review article is to firstly describe the physics and injury profile from these different devices and secondly to present the current clinical evidence that underpins their medical management.

Transfusion therapy in hemorrhagic shock

PURPOSE OF REVIEW

Bleeding and death from hemorrhage remain a leading cause of morbidity and mortality in the trauma population. Early resuscitation of these gravely injured patients has changed significantly over the past several years. The concept of damage control resuscitation has expanded significantly with the experience of the US military in southwest Asia. This review will focus on this resuscitation strategy of transfusing blood products (red cells, plasma, and platelets) early and often in the exsanguinating patient.

RECENT FINDINGS

In trauma there are no randomized controlled trials comparing the current damage control hematology concept to more traditional resuscitation methods. But the overwhelming conclusion of the data available support the administration of a high ratio of plasma and platelets to packed red blood cells. Several large retrospective studies have shown ratios close to 1: 1 will result in higher survival.

SUMMARY

The current evidence supports that the acute coagulopathy of trauma is present in a high percentage of trauma patients. Patients who will require a massive transfusion will have improved outcomes the earlier that this is identified and the earlier that damage control hematology is instituted. Current evidence does not describe the best ratio but the preponderance of the data suggests it should be greater than 2: 3 plasma-to-packed red blood cells.