The impact of hypothermia on dilutional coagulopathy

Prevention of hypothermia in trauma victims - the HYPOTRAUM 2 study

INTRODUCTION

Hypothermia is common in trauma patients. It contributes to increasing mortality rate. Hypothermia is multifactorial, favoured by exposure to cold, severity of the patient's state and interventions such as infusion of fluids at room temperature.

AIM

To demonstrate that specific management of hypothermia (or of the risk of hypothermia) increases the number of trauma patients arriving at the hospital with a temperature >35°C.

DESIGN

This is a prospective, multicentre, open-label, pragmatic, cluster randomized clinical trial of an expected 1,200 trauma patients included by 12 out-of-hospital mobile intensive care units (MICU). Trauma patients are included in a prehospital setting if they present at least one of the following criteria known to be associated with an increased incidence of hypothermia: ambient temperature <18°C, Glasgow coma scale <15, systolic arterial blood pressure <100 mm Hg or body temperature <35°C. Patients are randomized, by cluster, to receive a conventional management or 'interventional' nursing management associating: continuous epitympanic temperature monitoring, early installation in the heated ambulance (temperature target >30°C controlled by infrared thermometer), protection by a survival blanket, and use of heated solutes (temperature objective >35°C controlled by infrared thermometer). The primary end point is the prevalence of hypothermia on arrival at the hospital. The hypothesis tested is a reduction from 20% to 13% in the prevalence of hypothermia. Secondary end points are to evaluate the interaction between the effectiveness of the measures taken and: (1) the severity of the patients assessed by the Revised Trauma Score; (2) the meteorological conditions when they are managed; (3) the time of care; and (4) therapeutic interventions.

DISCUSSION

This trial will assess the effectiveness of an invasive, out-of-hospital, temperature management on the onset of hypothermia in moderate to severe trauma patients.

IMPACT

Specific management of hypothermia is expected to decrease hypothermia in trauma patients.

Damage control strategy in bleeding trauma patients

Hemorrhagic shock is a main cause of death in severe trauma patients. Bleeding trauma patients have coagulopathy on admission, which may even be aggravated by incorrectly directed resuscitation. The damage control strategy is a very urgent and essential aspect of management considering the acute coagulopathy of trauma and the physiological status of bleeding trauma patients. This strategy has gained popularity over the past several years. Patients in extremis cannot withstand prolonged definitive surgical repair. Therefore, an abbreviated operation, referred to as damage control surgery (DCS), is needed. In addition to DCS, the likelihood of survival should be maximized for patients in extremis by providing appropriate critical care, including permissive hypotension, hemostatic resuscitation, minimization of crystalloid use, early use of tranexamic acid, and avoidance of hypothermia and hypocalcemia. This review presents an overview of the evolving strategy of damage control in bleeding trauma patients.

Controlled Multifactorial Coagulopathy: Effects of Dilution, Hypothermia, and Acidosis on Thrombin Generation In Vitro

BACKGROUND

Coagulopathy and hemostatic abnormalities remain a challenge in patients following trauma and major surgery. Coagulopathy in this setting has a multifactorial nature due to tissue injury, hemodilution, hypothermia, and acidosis, the severity of which may vary. In this study, we combined computational kinetic modeling and in vitro experimentation to investigate the effects of multifactorial coagulopathy on thrombin, the central enzyme in the coagulation system.

METHODS

We measured thrombin generation in platelet-poor plasma from 10 healthy volunteers using the calibrated automated thrombogram assay (CAT). We considered 3 temperature levels (31°C, 34°C, and 37°C), 3 pH levels (6.9, 7.1, and 7.4), and 3 degrees of dilution with normal saline (no dilution, 3-fold dilution, and 5-fold dilution). We measured thrombin-generation time courses for all possible combinations of these conditions. For each combination, we analyzed 2 scenarios: without and with (15 nM) supplementation of thrombomodulin, a key natural regulator of thrombin generation. For each measured thrombin time course, we recorded 5 quantitative parameters and analyzed them using multivariable regression. Moreover, for multiple combinations of coagulopathic conditions, we performed routine coagulation tests: prothrombin time (PT) and activated partial thromboplastin time (aPTT). We compared the experimental results with simulations using a newly developed version of our computational kinetic model of blood coagulation.

RESULTS

Regression analysis allowed us to identify trends in our data (P < 10). In both model simulations and experiments, dilution progressively reduced the peak of thrombin generation. However, we did not experimentally detect the model-predicted delay in the onset of thrombin generation. In accord with the model predictions, hypothermia delayed the onset of thrombin generation; it also increased the thrombin peak time (up to 1.30-fold). Moreover, as predicted by the kinetic model, the experiments showed that hypothermia increased the area under the thrombin curve (up to 1.97-fold); it also increased the height of the thrombin peak (up to 1.48-fold). Progressive acidosis reduced the velocity index by up to 24%; acidosis-induced changes in other thrombin generation parameters were much smaller or none. Acidosis increased PT by 14% but did not influence aPTT. In contrast, dilution markedly prolonged both PT and aPTT. In our experiments, thrombomodulin affected thrombin-generation parameters mainly in undiluted plasma.

CONCLUSIONS

Dilution with normal saline reduced the amount of generated thrombin, whereas hypothermia increased it and delayed the time of thrombin accumulation. In contrast, acidosis in vitro had little effect on thrombin generation.

How do external factors contribute to the hypocoagulative state in trauma-induced coagulopathy? - In vitro analysis of the lethal triad in trauma

Background

External factors following trauma and iatrogenic intervention influence blood coagulation and particularly clot formation. In particular, three external factors (in detail dilution via uncritical volume replacement, acidosis and hypothermia), in combination, referred to as the “lethal triad”, substantially aggravate the hypocoagulative state after trauma. Contribution of these external factors to the resulting hypocoagulative state in trauma and especially their influence on primary haemostasis has still not been investigated systematically.

This study aims to assess this contribution to the aggravating hypocoagulative state in trauma-induced coagulopathy (TIC) using an in vitro simulation assay. Emphasis is given to platelet contribution to clot formation and to the investigation of how platelet activation alters under the respective conditions.

Methods

To simulate the conditions of lethal triad in vitro, whole blood samples taken from five healthy volunteers were introduced to the respective conditions. Besides standard coagulation testing, thrombelastometric analysis and differentiated platelet mapping were performed.

Results

All three simulated conditions induced significant impairments of clot formation (clot formation time, CFT; α -angle) and propagation (maximum clot firmness, MCF; Diameter A5-A25), with the highest impact under hypothermia and dilution. Consistently, lethal triad resulted in an additive effect of all conditions. None of the simulated conditions induced a statistically relevant change in coagulation initiation assessed by EXTEM and FIBTEM thrombelastometry.

Platelet contribution to clot formation decreased gradually under the respective conditions, reaching statistical significance for simulated dilution, and attaining its greatest extent under the conditions of lethal triad (Δtrias/baseline 0.59; p = 0.01). Consistent, reduced CD62 expression levels were observed under experimental acidosis (Δacidosis/baseline 0.32; p = 0.006), dilution (Δdilution/baseline 0.34; p = 0.01) and lethal triad (Δlethal triad/baseline 0.24; p = 0.01).

Conclusion

The respective external factors of lethal triad play a pivotal role in the development of coagulopathy, essentially influencing the kinetics of clot formation, and to a varying extent clot diameter, as measured by thrombelastometry. Moreover, impairment of platelet function under the conditions of lethal triad plays a key role in the pathophysiology of TIC, resulting in reduced responsiveness to stimulation with ADP that might also be present after trauma. Our data indicate that impairment of primary haemostasis contribute to the hypocoagulative state in TIC after trauma aggravated by external factors of lethal triad.

ClotChip: A Microfluidic Dielectric Sensor for Point-of-Care Assessment of Hemostasis

This paper describes the design, fabrication, and testing of a microfluidic sensor for dielectric spectroscopy of human whole blood during coagulation. The sensor, termed ClotChip, employs a three-dimensional, parallel-plate, capacitive sensing structure with a floating electrode integrated into a microfluidic channel. Interfaced with an impedance analyzer, the ClotChip measures the complex relative dielectric permittivity, ϵ_r , of human whole blood in the frequency range of 40 Hz to 100 MHz. The temporal variation in the real part of the blood dielectric permittivity at 1 MHz features a time to reach a permittivity peak, , as well as a maximum change in permittivity after the peak, , as two distinct parameters of ClotChip readout. The ClotChip performance was benchmarked against rotational thromboelastometry (ROTEM) to evaluate the clinical utility of its readout parameters in capturing the clotting dynamics arising from coagulation factors and platelet activity. exhibited a very strong positive correlation ( r = 0.99, p < 0.0001) with the ROTEM clotting time parameter, whereas exhibited a strong positive correlation (r = 0.85,  p < 0.001) with the ROTEM maximum clot firmness parameter. This paper demonstrates the ClotChip potential as a point-of-care platform to assess the complete hemostatic process using <10 μL of human whole blood.

Prolonged targeted temperature management compromises thrombin generation: A randomised clinical trial

AIM

To investigate whether prolonged compared with standard duration of targeted temperature management (TTM) compromises coagulation.

METHODS

Comatose survivors after out-of-hospital cardiac arrest (n=82) were randomised to standard (24h) or prolonged (48h) duration of TTM at 33±1°C. Blood samples were drawn 22, 46 and 70h after attaining the target temperature. Samples were analysed for rotational thromboelastometry (ROTEM^® (EXTEM^®, INTEM^®, FIBTEM^® and HEPTEM^®)) and thrombin generation using the Calibrated Automated Thrombogram^® assay.

RESULTS

With the 22-h sample, we revealed no difference between groups in the ROTEM^® and thrombin generation results beside a slightly higher EXTEM^® and INTEM^® maximum velocity in the prolonged group (p-values≤0.04). With the 46-h sample, ROTEM^® showed no differences when using EXTEM^®; however, 11% (p<0.01) longer clotting time and 12% (p<0.01) longer time to maximum velocity were evident in the prolonged group than in the standard group when using INTEM^®. The prolonged group had reduced thrombin generation compared with the standard group as indicated by 30% longer lag time (p=0.04), 106nM decreased peak concentration (p<0.001), 36% longer time to peak (p=0.01) and 411 nM*minute decreased endogenous thrombin potential (p<0.001). With the 70-h sample, no differences in ROTEM^® results were found between groups. However, the prolonged group had reduced thrombin generation indicated by longer lag time, decreased peak concentration and longer time to peak (all p-values≤0.02) compared with the standard group.

CONCLUSION

Prolonged TTM in post-cardiac arrest patients impairs thrombin generation. ClinicalTrials.gov identifier: NCT02258360.

Active Thermoregulation Improves Outcome of Off-Pump Coronary Artery Bypass

During off-pump coronary artery bypass grafting, hypothermia increases vasoconstriction, myocardial afterload, coagulopathy and postoperative bleeding. Traditional thermoregulatory techniques do not maintain core body temperature intraoperatively. The efficacy of a commercially available, computer-controlled, water-circulating, dorsal surface, active warming system for thermoregulatory control was evaluated. All patients who underwent non-emergency off-pump coronary bypass grafting by a single surgeon in a 1-year period were studied: the thermoregulation device was used in 50 cases and unavailable for use in 19. The patients who underwent active thermoregulation demonstrated significantly improved core body temperatures compared to the controls: lowest intraoperative, 35.8°C ± 0.1°C vs. 35.0°C ± 0.2°C; immediately postoperative, 36.5°C ± 0.1°C vs. 35.6°C ± 0.2°C; and 1-hour postoperative, 36.6°C ± 0.1°C vs. 35.9°C ± 0.2°C. Thermoregulated patients had significantly reduced 24-hour chest tube drainage (764 ± 38 vs. 1227 ± 183 mL), packed red blood cell transfusions (1.4 ± 0.2 vs. 3.3 ± 0.7 units), time to extubation (6.8 ± 0.5 vs. 11.4 ± 2.3 hours), intensive care unit stay (1.3 ± 0.1 vs. 2.0 ± 0.3 days), and hospital stay (4.3 ± 0.1 vs. 5.1 ± 0.3 days).

A recommended early goal-directed management guideline for the prevention of hypothermia-related transfusion, morbidity, and mortality in severely injured trauma patients

Hypothermia is present in up to two-thirds of patients with severe injury, although it is often disregarded during the initial resuscitation. Studies have revealed that hypothermia is associated with mortality in a large percentage of trauma cases when the patient's temperature is below 32 °C. Risk factors include the severity of injury, wet clothing, low transport unit temperature, use of anesthesia, and prolonged surgery. Fortunately, associated coagulation disorders have been shown to completely resolve with aggressive warming. Selected passive and active warming techniques can be applied in damage control resuscitation. While treatment guidelines exist for acidosis and bleeding, there is no evidence-based approach to managing hypothermia in trauma patients. We synthesized a goal-directed algorithm for warming the severely injured patient that can be directly incorporated into current Advanced Trauma Life Support guidelines. This involves the early use of warming blankets and removal of wet clothing in the prehospital phase followed by aggressive rewarming on arrival at the hospital if the patient's injuries require damage control therapy. Future research in hypothermia management should concentrate on applying this treatment algorithm and should evaluate its influence on patient outcomes. This treatment strategy may help to reduce blood loss and improve morbidity and mortality in this population of patients.

Activated clotting time test alone is inadequate to optimize therapeutic heparin dosage adjustment during post-cardiopulmonary resuscitational extracorporeal membrane oxygenation (e-CPR)

BACKGROUND

We conducted an observational study to evaluate the relationship between activated clotting time (ACT) and activated partial thromboplastin time (aPTT) tests, anticipating the possibility that the ACT will become a substitute test for the aPTT in post-CPR extracorporeal membrane oxygenation (e-CPR).

PATIENTS AND METHODS

Three hundred and fifteen paired ACT and aPTT samples were derived from 60 in-hospital e-CPR patients and were divided into three groups according to the observed ACT value: low level (ACT < 170 s, Group A), intended target level (ACT 170-210 s Group B) and high level (ACT > 210 s, Group C). The relationship of aPTT in each group was analyzed.

RESULTS

The mean ACT and aPTT values were 189.39 ± 48.27 s (IQR, 163-202) and 71.85 ± 45.32 s (IQR, 44.5-81.8), respectively. Although the observed mean ACT value of 189.39 s was similar to the intended mean target value of 190 s (p = 0.823), the observed mean aPTT value (71.85 s) was significantly lower than the predicted mean target value (77.5 s, p = 0.027). Despite the mean ACT values being significantly different in each group (p < 0.0001), the mean aPTT values were not statistically different between Groups A and B (p = 0.317). Of the Group B samples (n = 139), only 31 samples (22.3%) met the optimal therapeutic aPTT range. Pearson's correlation coefficient for Group B showed only a weak correlation between ACT and aPTT (r = 0.177; p = 0.037).

CONCLUSIONS

Our study demonstrates that the ACT test alone does not seem to be enough to optimize therapeutic heparin dosage adjustment during e-CPR.

Correction of hypothermic and dilutional coagulopathy with concentrates of fibrinogen and factor XIII: an in vitro study with ROTEM

BACKGROUND

Fibrinogen concentrate treatment can improve coagulation during massive traumatic bleeding. The aim of this in vitro study was to determine whether fibrinogen concentrate, or a combination of factor XIII and fibrinogen concentrates, could reverse a haemodilution-induced coagulopathy during hypothermia.

METHODS

Citrated venous blood from 10 healthy volunteers was diluted in vitro by 33% with 130/0.42 hydroxyethyl starch (HES) or Ringer's acetate (RAc). The effects of fibrinogen concentrate corresponding to 4 gram per 70 kg, or a combination of the same dose of fibrinogen with factor XIII (20 IU per kg), were measured using rotational thromboelastometry (ROTEM). The blood was analysed at 33°C or 37°C with ROTEM EXTEM and FIBTEM reagents. Clotting time (CT), clot formation time (CFT), alpha angle (AA) and maximal clot formation (MCF) were recorded.

RESULTS

Fibrinogen with or without factor XIII improved all ROTEM parameters in either solution irrespective of temperature, with the exception of EXTEM-AA and EXTEM-CFT in HES haemodilution. Fibrinogen increased FIBTEM-MCF more in the samples diluted with RAc than HES, particularly in presence of factor XIII.

CONCLUSIONS

Fibrinogen improved in vitro haemodilution-induced coagulopathy at both 33°C and 37°C, though more efficiently after crystalloid than HES haemodilution. Factor XIII had an additional effect on FIBTEM-MCF, but only after crystalloid dilution.

Mild induced hypothermia: effects on sepsis-related coagulopathy--results from a randomized controlled trial

INTRODUCTION

Coagulopathy associates with poor outcome in sepsis. Mild induced hypothermia has been proposed as treatment in sepsis but it is not known whether this intervention worsens functional coagulopathy.

MATERIALS AND METHODS

Interim analysis data from an ongoing randomized controlled trial; The Cooling And Surviving Septic shock (CASS) study. Patients suffering severe sepsis/septic shock are allocated to either mild induced hypothermia (cooling to 32-34°C for 24hours) or control (uncontrolled temperature).

TRIAL REGISTRATION

NCT01455116. Thrombelastography (TEG) is performed three times during the first day after study enrollment in all patients. Reaction time (R), maximum amplitude (MA) and patients' characteristics are here reported.

RESULTS

One hundred patients (control n=50 and intervention n=50; male n=59; median age 68years) with complete TEG during follow-up were included. At enrollment, 3%, 38%, and 59% had a hypocoagulable, normocoagulable, and hypercoagulable TEG clot strength (MA), respectively. In the hypothermia group, functional coagulopathy improved during the hypothermia phase, measured by R and MA, in patients with hypercoagulation as well as in patients with hypocoagulation (correlation between ΔR and initial R: rho=-0.60, p<0.0001 and correlation between ΔMA and initial MA: rho=-0.50, p=0.0002). Similar results were not observed in the control group neither for R (rho=-0.03, p=0.8247) nor MA (rho=-0.15, p=0.3115).

CONCLUSION

Mild induced hypothermia did seem to improve functional coagulopathy in septic patients. This improvement of functional coagulopathy parameters during the hypothermia intervention persisted after rewarming. Randomized trials are warranted to determine whether the positive effect on sepsis-related coagulopathy can be transformed to improved survival.

Relationship Between Hypothermia and Blood Loss in Adult Patients Undergoing Open Lumbar Spine Surgery

Context: Intraoperative blood loss during open lumbar spine surgery is associated with adverse events and is a contributor to higher medical costs. Intraoperative hypothermia has been shown to increase blood loss and postoperative allogeneic blood transfusion rates in other realms of orthopedic surgery, but it has not been studied extensively in patients undergoing spine surgery. Objective: To determine whether a clinically relevant association exists between intraoperative core body temperature and blood loss or transfusion rates in adult patients undergoing open lumbar spine surgery. Methods: In this retrospective medical record review, the surgical records of 174 adult patients who underwent open, nonmicroscopically assisted lumbar spine surgery performed by a single surgeon at a single institution were evaluated. Maximum, minimum, and average temperature, hypothermic temperature, and temperature range parameters were compared with intraoperative, total, and net blood loss and blood transfusion parameters. Additional patient demographic and perioperative characteristics were compared with blood loss and transfusion parameters to determine potential confounders. Analysis of variance, Spearman rank correlation, and generalized multiple linear regression analysis were performed to test for an association between temperature and blood loss or allogeneic transfusion rates. Statistical significance was set at P≤.05. Results: After implementation of exclusion criteria, 160 patient records and 168 surgical procedures were included in the analysis. For patients whose temperature decreased to a hypothermic level at some point during the procedure, hypothermic maximum temperature was protective against blood loss on bivariate analysis (P≤.02), but this finding lost significance after multivariate regression analysis (P>.09). Temperature range was associated with increased blood loss on bivariate analyses (P<.001) but also lost significance after adjusting for covariates in regression analysis (P≥.65). Surgery type (P≤.001) and operative time (P≤.001) were the most robust predictors of increased blood loss (P=.005) and were significantly associated with temperature (P<.001). Conclusion: No effect was found on perioperative blood loss from any temperature parameter or hypothermia in adult patients who underwent lumbar spine surgery once covariates were controlled for with multivariate analysis. One possible interpretation of these results is that the effect of temperature on blood loss can be explained by its strong relationship to the confounders of operative time and surgery type. J Am Osteopath Assoc. 2014;114(11):828-838 doi: 10.7556/jaoa.2014.169

Computational analysis of the effects of reduced temperature on thrombin generation: the contributions of hypothermia to coagulopathy

BACKGROUND

Hypothermia, which can result from tissue hypoperfusion, body exposure, and transfusion of cold resuscitation fluids, is a major factor contributing to coagulopathy of trauma and surgery. Despite considerable efforts, the mechanisms of hypothermia-induced blood coagulation impairment have not been fully understood. We introduce a kinetic modeling approach to investigate the effects of hypothermia on thrombin generation.

METHODS

We extended a validated computational model to predict and analyze the impact of low temperatures (with or without concomitant blood dilution) on thrombin generation and its quantitative parameters. The computational model reflects the existing knowledge about the mechanistic details of thrombin generation biochemistry. We performed the analysis for an "average" subject, as well as for 472 subjects in the control group of the Leiden Thrombophilia Study.

RESULTS

We computed and analyzed thousands of kinetic curves characterizing the generation of thrombin and the formation of the thrombin-antithrombin complex (TAT). In all simulations, hypothermia in the temperature interval 31°C to 36°C progressively slowed down thrombin generation, as reflected by clotting time, thrombin peak time, and prothrombin time, which increased in all subjects (P < 10(-5)). Maximum slope of the thrombin curve was progressively decreased, and the area under the thrombin curve was increased in hypothermia (P < 10(-5)); thrombin peak height remained practically unaffected. TAT formation was noticeably delayed (P < 10(-5)), but the final TAT levels were not significantly affected. Hypothermia-induced fold changes in the affected thrombin generation parameters were larger for lower temperatures, but were practically independent of the parameter itself and of the subjects' clotting factor composition, despite substantial variability in the subject group. Hypothermia and blood dilution acted additively on the thrombin generation parameters.

CONCLUSIONS

We developed a general computational strategy that can be used to simulate the effects of changing temperature on the kinetics of biochemical systems and applied this strategy to analyze the effects of hypothermia on thrombin generation. We found that thrombin generation can be noticeably impaired in subjects with different blood plasma composition even in moderate hypothermia. Our work provides mechanistic support to the notion that thrombin generation impairment may be a key factor in coagulopathy induced by hypothermia and complicated by blood plasma dilution.

Damage control in the injured patient

The damage control concept is an essential component in the management of severely injured patients. The principles in sequence are as follows: (1) abbreviated surgical procedures limited to haemorrhage and contamination control; (2) correction of physiological derangements; (3) definitive surgical procedures. Although originally described in the management of major abdominal injuries, the concept has been extended to include thoracic, vascular, orthopedic, and neurosurgical procedures, as well as anesthesia and resuscitative strategies.

Free oscillation rheometry monitoring of haemodilution and hypothermia and correction with fibrinogen and factor XIII concentrates

Background

Haemodilution and hypothermia induce coagulopathy separately, but their combined effect on coagulation has not been widely studied. Fibrinogen concentrate can correct dilutional coagulopathy and has an additional effect when combined with factor XIII concentrate. However, their effect on dilutional coagulopathy concomitant with hypothermia has not been studied previously. Free oscillation rheometry – FOR (Reorox®) – is a novel viscoelastic haemostatic assay that has not been studied in this context before.

Methods

Blood from 10 healthy volunteers was diluted by 33% with hydroxyethyl starch or Ringer’s acetate solutions. Effects of fibrinogen added in vitro with and without factor XIII were studied at 33°C and 37°C. Coagulation velocity (coagulation time) and clot strength (elasticity) were assessed with FOR. Coagulation was initiated in vitro with thromboplastin alone, or thromboplastin plus a platelet inhibitor.

Results

Hydroxyethyl starch increased the coagulation time and decreased clot strength significantly more than Ringer’s acetate solution, both in the presence and absence of a platelet inhibitor. There was a significant interaction between haemodilution with hydroxyethyl starch and hypothermia, resulting in increased coagulation time. After addition of fibrinogen, coagulation time shortened and elasticity increased, with the exception of fibrinogen-dependent clot strength (i.e., elasticity in the presence of a platelet inhibitor) after hydroxyethyl starch haemodilution. Factor XIII had an additional effect with fibrinogen on fibrinogen-dependent clot strength in blood diluted with Ringer’s acetate solution. Hypothermia did not influence any of the coagulation factor effects.

Conclusions

Both haemodilution and mild hypothermia impaired coagulation. Coagulopathy was more pronounced after haemodilution with hydroxyethyl starch than with Ringer’s acetate. Addition of fibrinogen with factor XIII was unable to reverse hydroxyethyl starch induced clot instability, but improved coagulation in blood diluted with Ringer’s acetate solution. Fibrinogen improved coagulation irrespective of hypothermia.

Impact of prehospital hypothermia on transfusion requirements and outcomes

BACKGROUND

Prehospital hypothermia (PH) is known to increase mortality following traumatic injury. PH relationship with transfusion requirements has not been documented. The purpose of this investigation was to analyze the impact of PH on blood product requirements and subsequent outcomes.

METHODS

The Los Angeles County Trauma System Database was queried for all patients admitted between 2005 and 2009. Demographics, physiologic parameters, and transfusion requirements were obtained and dichotomized by admission temperatures with a core temperature of less than 36.5 °C considered hypothermic. Multivariate analysis was performed to determine factors contributing to transfusion requirements and to derive adjusted odds ratios (AORs) for mortality and rates of adult respiratory distress syndrome and pneumonia.

RESULTS

A total of 21,023 patients were analyzed in our study with 44.6% presenting with PH. Hypothermic patients required 26% more fluid resuscitation (p < 0.001) in the emergency department and 17% more total blood products (p < 0.001) than those who were admitted with a normal temperature. There was a trend toward an increase in emergency department transfusion (8%, p = 0.06). PH was independently associated with the need for a transfusion (AOR, 1.1; p = 0.047), increased mortality (AOR, 2.0; p < 0.01), as well as incidence of adult respiratory distress syndrome (AOR, 1.8; p < 0.05) and pneumonia (AOR, 2.6; p < 0.01).

CONCLUSION

PH is associated with increased transfusion and fluid requirements and subsequently worse outcomes. Interventions that correct hypothermia may decrease transfusion requirements and improve outcomes. Prospective studies investigating correction of hypothermia in trauma patients are warranted.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.

Successful resuscitation after multiple injuries in the wilderness

BACKGROUND

Survival of blunt trauma associated with hypothermic and hemorrhagic cardiac arrest in wilderness areas is extremely rare.

CASE REPORT

We describe a case of a 19-year-old female college sophomore who, while glissading down Mt. Adams, had a 400-pound boulder strike her back and left pelvis, propelling her 40 feet down the mountain to land face down in the snow at 7000 feet. It took 4 h from the time of injury until the arrival of the helicopter at our Emergency Department and Trauma Center. The patient lost vital signs en route and had no CO(2) production. A cardiothoracic surgeon was the trauma surgeon on call. The patient was taken directly from the helipad to the operating room, where cutdowns enabled initial intravenous access, median sternotomy and pericardiotomy open heart massage, massive transfusion, chest and abdominal cavity irrigations with warm saline, correction of acid base imbalances and coagulopathies, and epicardial pacing that led to a successful reanimation of the patient. The patient was rewarmed without extracorporeal membrane oxygenation or heat exchangers. The ensuing multiple organ failures (heart, lungs, kidneys, intestines, brain, and immune system) and rhabdomyolysis led to a 2-month intensive care unit stay. She received over 120 units of blood and blood products. The patient regained cognitive function, mobility, and overcame multiple organ failure.

CONCLUSION

This report is presented to increase awareness of the potential survivability in hypothermia, and to recognize the heroic efforts of the emergency services personnel whose efforts saved the patient's life.

Liver packing during elective surgery: an option that can be considered

BACKGROUND

Packing is a life-saving procedure in patients undergoing emergency surgery for blunt hepatic trauma, especially when massive blood transfusions, acidosis, or hypothermia have resulted in coagulation disorders. The purpose of this study was to apply this concept to the setting of elective liver surgery.

METHODS

Elective packing was performed in 7 patients who had sustained prolonged bleeding mainly related to partial outflow obstruction during the course of liver resection (n = 3) or transplantation (n = 4). At the time of packing, conventional methods of hemostasis had failed and surgery had lasted for 490 (range, 380-695) minutes, blood loss was 5,700 (range, 2,100-13,700) ml, and all patients had coagulation disorders (prothrombin time PT <30%, platelets <45 g/l), hypothermia (body temperature 35.4 °C), acidosis (median blood pH 7.24; serum lactate 6.5 mmol/l) and required catecholamine support.

RESULTS

Unpacking was performed after a median of 37 (range, 26-60) hours. At that time, all patients were normothermic, with platelet counts >45 g/l, PT >30%, and restored acid-base balance. Active bleeding had stopped, and secondary fascia closure was feasible. With a minimum follow-up of 6 months, all patients are alive without sequel.

CONCLUSIONS

Packing is a safe and efficient means to control venous bleeding when conventional methods of hemostasis have failed, knowing that commonly the reason for failure of conventional method of hemostasis is partial outflow obstruction.

Trauma induces a hypercoagulable state that is resistant to hypothermia as measured by thrombelastogram

BACKGROUND

The aim of this study was to test the hypothesis that severely injured trauma patients would be hypercoagulable compared with controls measured by thromboelastography and that this hypercoagulability would persist over a broad range of temperatures.

METHODS

A prospective study evaluating the effects of temperature on coagulation in trauma patients with Injury Severity Scores ≥ 15 and controls was completed. Thromboelastography was performed 24 hours after admission at 4 temperatures ranging from 32°C to 38°C.

RESULTS

Ninety-two subjects (46 patients) were analyzed. Patients had a median Injury Severity Score of 20 (interquartile range, 16–26). Time to clot formation increased (P < .001) and fibrin cross-linking decreased (P < .01) in both groups as temperature decreased. Between groups, time to clot formation, fibrin cross-linking, and clot strength were significantly different at each temperature (P < .01), with patients being more hypercoagulable. Time to clot formation and fibrin cross-linking were more affected by temperature in controls compared with patients (P < .02).

CONCLUSIONS

Severely injured patients are more hypercoagulable than controls throughout a broad range of temperature. Decreasing temperature has a greater effect on coagulation in controls compared with patients.

Active intravascular rewarming for hypothermia associated with traumatic injury: early experience with a new technique

Hypothermia is a significant contributor to mortality in severely injured patients. Rewarming is an enormous challenge, especially in those who require operative or angiographic intervention. In this patient population, external warming methods are only capable of reducing further heat loss, whereas active rewarming adds heat to the body's core but is invasive. This article analyzes our initial experience with a minimally invasive, continuous, automated, and easily portable intravascular rewarming technique using the Alsius Corporation's CoolGard system. The records of 11 hypothermic critically injured patients presenting to our level 1 trauma center over a 6-month period were reviewed. The patients' mean age was 39 +/- 22 years, 7 (64%) were male, and 7 (64%) had blunt mechanisms of injury. The mean injury severity score was 40 +/- 16, and the mean initial systolic blood pressure was 91 +/- 60 mm Hg. The mean core temperature at the initiation of rewarming was 33.6 +/- 1.0 degrees C, and the mean rewarming rate was 1.5 +/- 1.0 degrees C/h. Six patients died (55%), two of acute exsanguination and four of unsurvivable traumatic brain injuries. One patient developed a deep vein thrombosis at the femoral catheter site and experienced a nonfatal pulmonary embolus. Our experience demonstrates that active intravascular balloon-catheter rewarming represents a practical, automated technique for the immediate and continuous treatment of hypothermia in all phases of the acute care of trauma patients.

Therapeutic mild hypothermia: effects on coagulopathy and survival in a rat hemorrhagic shock model

OBJECTIVE

: To determine the effects of therapeutic hypothermia on coagulation parameters during hemorrhagic shock (HS) and fluid resuscitation and on survival, in a rat HS model.

METHODS

: Under light anesthesia and spontaneous breathing, 24 rats underwent HS (phase I) for 90 minutes, during which 2.5 mL/100 g blood was withdrawn over 15 minutes; fluid resuscitation (phase II) for 60 minutes, during which no blood was reinfused but 5.0 mL/100 g lactated Ringer's solution was infused over 30 minutes; and an observation (phase III) without anesthesia until 72 hour. After the volume-controlled hemorrhage, rats were randomized into a hypothermia group (n = 12, 33 degrees C) or a normothermia group (n = 12, 38 degrees C). The rectal temperature in each group was maintained during phases I and II. Whole blood coagulopathy was assessed by Sonoclot analysis (SA) at baseline and the end of phases I and II. Fibrinolysis parameters of thrombin-antithrombin III complex and plasma-alpha-2-plasmin inhibitor complex were also monitored.

RESULTS

: At 72 hour, 10 of 12 hypothermia group rats, and 5 of 12 normothermia group rats remained alive (p < 0.05). Fluid resuscitation significantly decreased hematocrit (20% +/- 5%) compared with baseline (33% +/- 5%; p < 0.05) in all rats. SA showed no significant differences between groups at the end of phase I. However, at the end of phase of II, SA revealed a decreased "clot rate" in hypothermia compared with normothermia (22 clot signal/min +/- 11 clot signal/min vs. 34 clot signal/min +/- 14 clot signal/min; p < 0.05) and a prolonged "time to peak" in hypothermia (15 minutes +/- 5 minutes versus 6 minutes +/- 2 minutes; p < 0.05). No differences in thrombin-antithrombin III complex and plasma-alpha-2-plasmin inhibitor complex values were seen between groups throughout the experiment.

CONCLUSIONS

: Therapeutic mild hypothermia of 33 degrees C did not cause coagulopathy during HS, but did impair SA coagulation parameters during fluid resuscitation, probably because of dilution. Hypothermia also prolonged survival after HS. Impairments to coagulation parameters did not worsen outcomes in the rat HS model.

Impact of hypothermia in the rural, pediatric trauma patient

OBJECTIVE

Hypothermia is an independent predictor of mortality in adult trauma studies. However, the impact of hypothermia on the pediatric trauma population has not been described. The purpose of this study is to evaluate hypothermia as a cofactor to mortality, complications, and among survivors, hospital length of stay parameters in the pediatric trauma population.

DESIGN

Retrospective review of a prospectively collected database (National Trauma Registry of the American College of Surgeons) over a 5-yr period (July 2002 to June 2007).

SETTING

A rural, level I trauma center.

PATIENTS

One thousand six hundred twenty-nine pediatric patients admitted with a traumatic injury.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Multivariate regression models were used to evaluate the association of hypothermia with mortality, infectious complications, organ dysfunction, and among survivors, hospital length of stay parameters. Of 1,629 pediatric trauma patients admitted, 182 (11.1%) patients were hypothermic (temperature below 36 degrees C) on admission. Hypothermia had an adjusted odds ratio (AOR) of 2.41 (95% confidence interval [CI], 1.12-5.22, p = .025) for mortality. After controlling for covariates, hypothermia had associations with developing pneumonia (AOR, 0.185, 95% CI, 0.040-0.853; p = .031) and a bleeding diathesis (AOR, 3.14, 95% CI, 1.04-9.44; p = .042). The median days in the hospital, intensive care unit (ICU), and ventilator were longer in the hypothermic cohort; however, after controlling for covariates, hypothermia was not associated with differences in hospital days, ICU days, or ventilator days.

CONCLUSIONS

Hypothermia is a common problem at admission among pediatric trauma patients. Hypothermia is associated with an increase in the odds of death and the development of a bleeding diathesis, while having decreased odds for developing pneumonia. While the length of stay indicators were longer in the hypothermic cohort among survivors, no significant association was noted with hypothermia for hospital, ICU, or ventilator days after controlling for confounders.

Impact of hypothermia (below 36 degrees C) in the rural trauma patient

BACKGROUND

Hypothermia is an independent predictor of mortality based on urban studies. But this association has not been described in the rural setting. This study's purpose was to evaluate hypothermia as a cofactor to mortality, complications, and hospital length of stay (LOS) parameters in the rural trauma setting.

STUDY DESIGN

The National Trauma Registry of the American College of Surgeons database for our rural, Level I trauma center was queried for a 5-year period (July 2002 to June 2007) to identify adult trauma patients. Multivariate regression models were used to evaluate the association of hypothermia with mortality; infectious complications; organ dysfunction; and, among survivors, hospital LOS parameters.

RESULTS

Of 9,482 adult patients admitted, 1,490 (15.7%) patients were hypothermic. Hypothermia had an adjusted odds ratio of 1.70 for mortality (95% CI, 1.35 to 2.12; p < 0.001). After controlling for covariates, hypothermia was not significantly associated with infectious complications or organ dysfunction, except for arrhythmia (adjusted odds ratio, 1.40; CI, 1.03 to 1.90; p = 0.031). Hypothermia was not associated with a difference in ICU (p = 0.310) or ventilator (p = 0.144) LOS. But a slight increase in hospital days was noted in the hypothermic patient (hazards ratio, 0.890 for discharge; 95% CI, 0.838 to 0.946; p < 0.001).

CONCLUSIONS

Hypothermia is a common problem at admission in a rural trauma center. It is associated with an increase in hospitalized days but not with increased ICU or ventilator days among survivors. Other than arrhythmias, it was not significantly associated with other National Trauma Registry of the American College of Surgeons infectious or organ dysfunction complications. Hypothermia is an independent risk factor for mortality in the rural trauma patient.

Preconditions of hemostasis in trauma: a review. The influence of acidosis, hypocalcemia, anemia, and hypothermia on functional hemostasis in trauma

BACKGROUND

Beside the often discussed topics of consumption and dilution coagulopathy, additional perioperative impairments of coagulation are caused by acidosis, hypocalcemia, anemia, hypothermia, and combinations.

METHODS

Reviewing current literature, cutoff values of these parameters become obvious at which therapy should commence.

RESULTS

A notable impairment of hemostasis arises at a pH < or = 7.1. Similar effects are caused by a BE of -12.5 or less. Thus, in case of severe bleeding, buffering toward physiologic pH values is recommended, especially with massive transfusions of older RBCCs displaying exhausted red blood cell buffer systems. It completes the optimization of the volume homeostasis to ensure an adequate tissue perfusion. Combining beneficial cardiovascular and coagulation effects, the level for ionized calcium concentration should be held > or = 0.9 mmol/L. From the hemostatic point of view, the optimal Hct is higher than the one required for oxygenation. Even without a "classical" transfusion trigger, the therapy of acute, persistent bleeding should aim at reaching an Hct > or = 30%. A core temperature of < or = 34 degrees C causes a decisive impairment of hemostasis. A controlled hypotensive fluid resuscitation should aim at reaching a mean arterial pressure of > or = 65 mm Hg (possibly higher for cerebral trauma). Prevention and later aggressive therapy of hypothermia by exclusive infusion of warmed fluids and the use of warming devices are prerequisites for the cure of traumatic coagulopathy. Combined appearance of single preconditions cause additive impairments of the coagulation system.

CONCLUSIONS

The prevention and timely correction, especially of the combination acidosis plus hypothermia, is crucial for the treatment of hemorrhagic coagulopathy.

Anaesthetic issues related to postpartum haemorrhage (excluding antishock garments)

The obstetric anaesthetist is a key member of the multidisciplinary team required to manage postpartum haemorrhage, having been trained in resuscitation and being experienced in managing haemorrhage and in monitoring and caring for the critically ill patient. The diagnosis of shock, initial resuscitation controversies surrounding fluid replacement, cell salvage in obstetrics and monitoring are discussed.

Thrombelastography is better than PT, aPTT, and activated clotting time in detecting clinically relevant clotting abnormalities after hypothermia, hemorrhagic shock and resuscitation in pigs

BACKGROUND

Hypothermia and hemorrhagic shock contribute to coagulopathy after trauma. In this study, we investigated the independent and combined effects of hypothermia and hemorrhage with resuscitation on coagulation in swine and evaluated clinically relevant tests of coagulation.

METHODS

Pigs (n = 24) were randomized into four groups of six animals each: sham control, hypothermia, hemorrhage with resuscitation, and hypothermia, hemorrhage with resuscitation combined. Hypothermia to 32 degrees C was induced with a cold blanket. Hemorrhage was induced by bleeding 35% of total blood volume followed by resuscitation with lactated Ringer's solution. Coagulation was assessed by thrombin generation, prothrombin time (PT), activated partial thromboplastin time (aPTT), activated clotting time (ACT), and thrombelastography (TEG) from blood samples taken at baseline and 4 hour after hypothermia and/or hemorrhage with resuscitation. Data were compared with analysis of variance.

RESULTS

Baseline values were similar among groups. There were no changes in any measurements in the control group. Compared with baseline values, hemorrhage with resuscitation increased lactate to 140% +/- 15% (p < 0.05). Hypothermia decreased platelets to 73% +/- 3% (p < 0.05) with no effect on fibrinogen. Hemorrhage with resuscitation reduced platelets to 72% +/- 4% and fibrinogen to 71% +/- 3% (both p < 0.05), with similar decreases in platelets and fibrinogen observed in the combined group. Thrombin generation was decreased to 75% +/- 4% in hypothermia, 67% +/- 6% in hemorrhage with resuscitation, and 75% +/- 10% in the combined group (all p < 0.05). There were no significant changes in PT or aPTT by hemorrhage or hypothermia. ACT was prolonged to 122% +/- 1% in hypothermia, 111% +/- 4% in hemorrhage with resuscitation, and 127% +/- 3% in the combined group (all p < 0.05). Hypothermia prolonged the initial clotting time (R) and clot formation time (K), and decreased clotting rapidity (alpha) (all p < 0.05). Hemorrhage with resuscitation only decreased clot strength (maximum amplitude [MA], p < 0.05). TEG parameters in the combined group reflected the abnormal R, K, MA, and alpha observed in the other groups.

CONCLUSION

Hypothermia inhibited clotting times and clotting rate, whereas hemorrhage impaired clot strength. Combining hypothermia with hemorrhage impaired all these clotting parameters. PT, aPTT were not sensitive whereas ACT was not specific in detecting these coagulation defects. Only TEG differentiated mechanism related to clotting abnormalities, and thus may allow focused treatment of clotting alterations associated with hypothermia and hemorrhagic shock.

In vitro effect of activated recombinant factor VII (rFVIIa) on coagulation properties of human blood at hypothermic temperatures

BACKGROUND

Recombinant activated factor VII (rFVIIa) is currently administered off-label to control diffuse coagulopathic bleeding of patients with traumatic injuries. These patients are often cold, acidotic, and coagulopathic upon arrival and each responds differently to rFVIIa therapy. This study investigated the effects of hypothermia on clotting and the potential benefit of rFVIIa administration on blood coagulation at different hypothermic temperatures.

METHOD

Citrated blood samples were collected from eight healthy volunteers (20-45 years old) and incubated at 37 degrees C, 34 degrees C, 31 degrees C, and 28 degrees C for 30 minutes. rFVIIa (1.26 microg/mL equivalent to 90 microg/kg in vivo dose) or vehicle solution (saline) was added to each blood sample, incubated (10 minutes), and analyzed at the respective temperatures by standard coagulation tests and thrombelastography.

RESULTS

The clot reaction time of blood samples, measured as prothrombin time, activated partial thromboplastin time, and R time (thrombelastography analysis), was significantly prolonged at 31 degrees C or below compared with at 37 degrees C. The clot formation rate ([alpha] angle, maximum clotting velocity [Vmax]) was decreased at all cold temperatures. Maximum clot strength (maximum amplitude) was only affected (reduced) at 28 degrees C. Addition of rFVIIa shortened the prothrombin time, activated partial thromboplastin time, and R times at every temperature, surpassing the normal (37 degrees C) temperature values in 31 degrees C and 34 degrees C cold samples. Similarly, clot formation rate parameters (clotting time, [alpha] angle, Vmax) were also improved by rFVIIa addition and normothermic values were restored in 31 degrees C and 34 degrees C cold blood samples. rFVIIa did not affect maximum amplitude at any temperature.

CONCLUSIONS

Mild to moderate hypothermia delayed the initial clot reaction and reduced clot formation rate without affecting ultimate clot strength. FVIIa effectively compensated for the adverse effects of hypothermia except in severe cases. These results suggest that administration of FVIIa should be beneficial in enhancing hemostasis in hypothermic trauma patients without the need for prior correction of the patient's body temperature.

Trauma and aggressive homeostasis management

Three important issues concerning homeostasis in the acute care of trauma patients that are related directly to the stress response are hyperglycemia, lactic acidosis, and hypothermia. Recently, there has been a resurgence of interest in investigating the effects of aggressive thermal and glucose concentration and volume resuscitation on outcomes in critically ill and trauma patients. Significant reason exists to question the "conventional wisdom" relating to current approaches to restoring homeostasis in this patient population.

Is there a self-preserving hypothermic mechanism in shock?

Hypoxia-induced hypothermia (HIH) is regarded as an adaptive response to hypoxia in a variety of creatures, but no details of the mechanism have yet been elucidated in the clinical setting. This study was designed to analyze alteration of core body temperature with hemorrhagic shock and to clarify HIH in the clinical setting. Patients were categorized in the hemorrhage shock (S, n = 15) or cardiopulmonary arrest (C, n = 88) group. The tympanic membrane temperature (TMT) was measured, and the length of the interval of call-to-arrival (CTA) at a hospital was set as the time-course parameter. There was a significant negative linear relationship between CTA interval and TMT (S group: TMT = -0.055 degrees C, CTA = +36.1 min, r = -0.833, P < 0.001; C group: TMT = -0.046 degrees C, CTA = +36.3 min, r = -0.548, P < 0.001). Analysis of variance revealed no significant difference in the slope of the regression lines of both groups. However, when the CTA interval was used as a covariate, there was a significant difference in the TMT (P = 0.014), which means that the regression line of the S group was significantly lower than that of the C group with time. Furthermore, in the S group, all patients were hypothermic (<35 degrees C) when their CTA interval was more than 20 min; on the other hand, in the C group, only 64 (75%) of 85 were hypothermic. Patients in S group were more likely to become hypothermic (P < 0.05). In humans with cellular hypoxia, HIH takes place, as seen in other animals. This result emphasizes the necessity for studies of analysis of the mechanisms of temperature control and determination of optimal body temperature during acute critical care.

Rahmenbedingungen für eine intakte Hämostase

A coagulopathy is an independent predictor of perioperative mortality. Therefore, maintenance of a functional coagulation system is an essential precondition to reduce morbidity and mortality in the perioperative setting. Sound coagulability also depends on prerequisites such as body temperature, acid-base balance, plasma calcium concentration and haematocrit. Severe trauma or perioperative bleeding can gravely influence these factors and boost the blood loss. Common global tests of coagulation are not helpful in this setting because they are conducted on plasma with a normalised temperature of 37 degrees C, an excess of calcium and a stabile acid-base balance. Hence, knowledge of the effects of altered prerequisites is a premise to avoid a possibly lethal coagulopathy. According to the current literature, an increased risk for clinically significant coagulopathy exists with a body temperature <or=34 degrees C, an acidosis <or=7.15, ionised calcium under 0.9 mmol/l or a haematocrit under 30-35%. A combination of these factors deteriorates the coagulopathy and hypothermia in addition to acidosis is especially harmful. Prevention of derangement of these factors should start as early as possible, i.e. in trauma patients at the scene of the accident and should be continued in the operating room.

Lactated Ringer's is Superior to Normal Saline in the Resuscitation of Uncontrolled Hemorrhagic Shock

BACKGROUND

Normal saline (NS) and lactated Ringer's solution (LR) continue to be used interchangeably for the resuscitation of hemorrhagic shock in some institutions. We hypothesized that, aside from hyperchloremic acidosis, NS resuscitation would be similar to that of LR in a swine model of uncontrolled hemorrhage.

METHODS

Twenty swine weighing a mean of 37 kg underwent invasive line placement, midline celiotomy, and splenectomy. After a 15-minute stabilization period, we recorded a baseline mean arterial pressure (MAP) and created a grade V liver injury. The animals bled freely for 30 minutes after which we measured blood loss. We blindly randomized the swine to receive NS (10 animals) versus LR (10 animals) to achieve and maintain the baseline MAP for 90 minutes postinjury. Laboratory values were obtained at baseline and upon completion of the 2-hour study period.

RESULTS

Initial blood loss was 25 mL/kg in the NS group and 22 mL/kg in the LR group (p = 0.54). Animals required 256.3 +/- 145.4 mL/kg of fluid in the NS group as compared with 125.7 +/- 67.3 mL/kg in the LR group (p = 0.04). The urine output was higher in the NS group (46.6 +/- 39.5 mL/kg versus 18.9 +/- 12.9 mL/kg, p = 0.04). Upon study completion, the NS group had a significant hyperchloremia (119 +/- 1.9 mEq/L versus 105 +/- 2.9 mEq/L, p < 0.01) with acidosis (7.28 +/- 0.12 versus 7.45 +/- 0.06, p < 0.01) in comparison to the LR group. In addition, resuscitation with NS resulted in significantly lower fibrinogen levels (99 +/- 21 mg/dL versus 123 +/- 20 mg/dL, p = 0.02). The serum lactate was 4.7 +/- 2.2 in the LR group and 1.7 +/- 1.7 in the NS swine (p < 0.01) at the end of the study.

CONCLUSIONS

Resuscitation of uncontrolled hemorrhagic shock with NS requires significantly greater volume and is associated with greater urine output, hyperchloremic acidosis, and dilutional coagulopathy as compared with LR. Resuscitation with LR results in an elevation of the lactate level that is not associated with acidosis. Lactated Ringer's solution is superior to NS for the resuscitation of uncontrolled hemorrhagic shock in swine.

Environmental Cold-Induced Injury

More than 650 deaths from hypothermia occur each year in the United States. Even minor deviation from normal temperature leads to important symptoms and disability. The most significant risk factors are advanced age, mental impairment, substance abuse, and injury. This article examines the incidence of hypothermia, its detrimental effect on trauma patients, and methods of rewarming the hypothermic patient. It also looks at the controversial protective role hypothermia might play in shock, organ transplantation, cardiac arrest, and brain injury. Finally, it examines cold injuries, including frostbite, chilblain, and trench foot, and makes recommendations for their treatment.

[Procedure for critical nonsurgical bleeding]

The improvement of surgical and nonsurgical approaches to control bleeding offers new strategies for overcoming coagulopathy. Massive hemorrhage is usually caused by a combination of surgical and coagulopathic bleeding. Coagulopathy is multifactorial and results from the dilution and consumption of both platelets and coagulation factors and dysfunction of the coagulation system. Blood component therapy continues to be a mainstay for this coagulopathy-related bleeding. However, the transfusion of red blood cells has been shown to be associated with post-injury infection and multiple organ failure. Therefore it is crucial to develop a clear strategy for correcting coagulopathy, preventing exsanguination, and minimizing the need for blood transfusion.

Koagulopathie

Coagulopathy after trauma is a major cause for uncontrolled hemorrhage in trauma victims. Approximately 40% of trauma related deaths are attributed to or caused by exsanguination. Therefore the prevention of coagulopathy is regarded as the leading cause of avoidable death in these patients. Massive hemorrhage after trauma is usually caused by a combination of surgical and coagulopathic bleeding. Coagulopathic bleeding is multifactorial, including dilution and consumption of both platelets and coagulation factors, as well as dysfunction of the coagulation system. Because of the high mortality associated with hypothermia, acidosis and progressive coagulopathy, this vicious circle is often referred to as the lethal triad, potentially leading to exsanguination. To overcome this coagulopahty-related bleeding an empiric therapy is often instituted by replacing blood components. However, the use of transfusion of red blood cells has been shown to be associated with post-injury infection and multiple organ failure. In the management of mass bleeding it is therefore crucial to have a clear strategy to prevent coagulopathy and to minimize the need for blood transfusion.

Critical care issues in the early management of severe trauma

Violent trauma and road traffic injuries kill more than 2.5 million people in the world every year, for a combined mortality of 48 deaths per 100,000 population per year. Most trauma deaths occur at the scene or in the first hour after trauma, with a proportion from 34% to 50% occurring in hospitals. Preventability of trauma deaths has been reported as high as 76% and as low as 1% in mature trauma systems. Critical care errors may occur in a half of hospital trauma deaths, in most of the cases contributing to the death. The most common critical care errors are related to airway and respiratory management, fluid resuscitation, neurotrauma diagnosis and support, and delayed diagnosis of critical lesions. A systematic approach to the trauma patient in the critical care unit would avoid errors and preventable deaths.

Damage Control Surgery for Abdominal Trauma

Damage control is not a modern concept, but the application of this approach represents a new paradigm in surgery, borne out of a need to save patients with severe exsanguinating injuries. Definitive control and repair may be accomplished in the immediate post injury setting but the physiological derangement due to massive shock state resulting from the severe injury and the resuscitation that follows, often leads to a fully repaired but dead patient. The vicious triad of death in trauma, namely hypothermia, acidosis and coagulopathy should be tackled by initial abbreviated laparotomy, correction of physiological derangements and finally definitive repair of all injuries at second laparotomy. The concept needs a dedicated team effort with careful patient selection for achieving the optimal results.

Recombinant factor VIIa in patients with coagulopathy secondary to anticoagulant therapy, cirrhosis, or severe traumatic injury: review of safety profile

BACKGROUND

In recent years, the hemostatic agent recombinant factor VIIa (rFVIIa) has emerged as a potentially new therapeutic agent for management of coagulopathy in patients with cirrhosis or following severe traumatic injury, a complex problem for clinicians in which standard treatment strategies are not always effective. As with other hemostatic agents, a primary safety concern of rFVIIa therapy is the theoretical possibility that systemic administration could confer an increased risk of thrombotic complications. So far, clinical experience indicates rFVIIa to be a safe treatment for currently approved indications within hemophilia. Little information is available, however, for patient populations outside this clinical setting.

STUDY DESIGN AND METHODS

This article reviews critical safety data obtained from 13 Novo Nordisk-sponsored clinical trials of rFVIIa in patients with coagulopathy secondary to anticoagulant therapy, cirrhosis, or severe traumatic injury.

RESULTS

Thrombotic adverse events were reported for 5.3 percent (23/430) of placebo-treated patients and 6.0 percent (45/748) of patients on active treatment. No significant difference was found between placebo-treated and rFVIIa-treated patients with respect to the incidence of thrombotic AEs, either on an individual trial basis or for these trial populations combined (p=0.57).

CONCLUSION

An important determinant for the safety profile reported here is likely to be the specific mechanism of action of rFVIIa, shown in experimental studies to be localized to the site of vascular injury where tissue factor is exposed.

Coagulopathy in the trauma patient

PURPOSE OF REVIEW

Homeostasis represents a delicate balance between hemostatic and fibrinolytic processes. This balance permits arrest of hemorrhage after mild injury but prevents thrombosis from occurring under normal circumstances. Trauma disturbs the equilibrium between hemostatic and fibrinolytic processes, frequently producing either a hypocoagulable state or a hypercoagulable state depending on the severity of injury, degree of hemorrhage, and the nature of the resuscitation. The purpose of this review is to describe the epidemiology and pathophysiology of coagulopathy after trauma and to discuss novel methods of treating it.

RECENT FINDINGS

Published reports during the past year focus on the pathophysiology of coagulopathy after trauma and novel methods of treatment. Individual effects of hypothermia and acidosis on clotting factors and platelet function have been described. The effects of varying resuscitation fluids on coagulopathy have also been described as well as the course of coagulopathy over time. Recombinant factor VIIa has emerged as a popular therapy for traumatic coagulopathy although a prospective randomized trial has yet to be published. The efficacy of several new dressings for the local control of hemorrhage has been reported.

SUMMARY

Changes in coagulation following trauma are characterized by a complex series of events that may result in either a hypocoagulable or a hypercoagulable state. Routinely analyzed coagulation parameters do not adequately describe this state and they are deficient for guiding its therapy. Several promising new agents are available for treating hemorrhage in coagulopathic trauma patients that should result in improved survival.