Administration of Recombinant Factor VIIa Decreases Blood Loss After Blunt Trauma in Noncoagulopathic Pigs

rFVIIa in trauma: a review and opinion-based guidelines

Recombinant activated factor seven (rFVIIa) is a novel and emerging therapy for the acquired coagulopathy associated with massive bleeding and hemorrhagic shock. The intent of this paper is to review the mechanism of action of rFVIIa, to discuss the current state of evidence regarding the safety and efficacy of rFVIIa, and to offer guidance regarding its use in severely traumatized patients. No study has demonstrated a survival benefit in humans. rFVIIa, is safe to use in the setting of severe trauma associated with ongoing bleeding and acquired coagulopathy. Doses of 80—200 μg/kg may be used after correction of thrombocytopenia and acidosis. Hypothermia should be corrected in any traumatized patient, but should not be a barrier to its administration. Definitive evidence supporting the use of rFVIIa is lacking, but ongoing studies will delineate survival benefits, dosing regimens, and adverse events associated with its use.

Recombinant Factor VIIa Reduces Bleeding after Blunt Liver Injury in a Pig Model of Dilutional Coagulopathy under Severe Hypothermia

Background

Recombinant factor VIIa (rFVIIa) is registered for use in haemophilia with inhibitors and other rare bleeding disorders, but has also been used in various other clinical conditions to terminate life-threatening bleeding. Underlying conditions (e.g. coagulopathy) and dosing may affect treatment efficacy. The objective of the present study was to evaluate the impact of increasing doses of rFVIIa on blood loss and coagulation assays in haemodiluted and hypothermic pigs undergoing blunt liver injury.

Methods

A grade III blunt liver injury was induced in 28 pigs after 70% haemodilution and cooling to 32.6–33.4°C. Ten minutes after trauma, animals randomly received placebo or 90, 180 or 360 μg/kg rFVIIa. Global coagulation parameters, thromboelastometry (TEM) and plasma thrombin generation (TG) were determined at different time points during the observation period of 120 minutes.

Results

Total blood loss was significantly lower following 90 μg/kg rFVIIa (1206 [1138–1470] mL) relative to placebo (2677 [2337–3068] mL; p<0.05), with no increased effect with higher dose levels of rFVIIa. Following trauma and haemodilution, coagulation was impaired relative to baseline in both TEM and TG analysis. At 60 and 120 minutes after trauma, TEM variables improved in the rFVIIa-treated animals compared with the placebo group. Similarly, rFVIIa improved coagulation kinetics in TG. As was observed with blood loss, no significant effect between different rFVIIa dose levels was found in TEM or TG. Macro- and microscopic post-mortem examination did not reveal any signs of thromboembolic events.

Conclusion

Early administration of 90 μg/kg rFVIIa reduced blood loss in pigs undergoing blunt liver injury even after severe haemodilution and hypothermia, with no further effect of higher dose levels. Coagulation assays showed impaired coagulation in coagulopathic animals, with a dose-independent improvement in animals treated with rFVIIa.

Modeling acute traumatic injury

Acute traumatic injury is a complex disease that has remained a leading cause of death, which affects all ages in our society. Direct mechanical insult to tissues may result in physiological and immunologic disturbances brought about by blood loss, coagulopathy, as well as ischemia and reperfusion insults. This inappropriate response leads to an abnormal release of endogenous mediators of inflammation that synergistically contribute to the incidence of morbidity and mortality. This aberrant activation and suppression of the immune system follows a bimodal pattern, wherein activation of the innate immune responses is followed by an anti-inflammatory response with suppression of the adaptive immunity, which can subsequently lead secondary insults and multiple organ dysfunction. Traumatic injury rodent and swine models have been used to describe many of the underlying pathologic mechanisms, which have led to an improved understanding of the morbidity and mortality associated with critically ill trauma patients. The enigmatic immunopathology of the human immunologic response after severe trauma, however, has never more been apparent and there grows a need for a clinically relevant animal model, which mimics this immune physiology to enhance the care of the most severely injured. This has necessitated preclinical studies in a more closely related model system, the nonhuman primate. In this review article, we summarize animal models of trauma that have provided insight into the clinical response and understanding of cellular mechanisms involved in the onset and progression of ischemia-reperfusion injury as well as describe future treatment options using immunomodulation-based strategies.

Pre-hospital resuscitation with HBOC-201 and rFVIIa compared to HBOC-201 alone in uncontrolled hemorrhagic shock in swine

In a previous dose escalation study our group found that combining 90μg/kg rFVIIa with HBOC-201 reduced blood loss and improved physiologic parameters compared to HBOC alone. In this follow-up study in a swine liver injury model, we found that while there were no adverse hematology effects and trends observed in the previous study were confirmed, statistical significance could not be reached. Additional pre-clinical studies are indicated to identify optimal components of a multifunctional blood substitute for clinical use in trauma.

Prothrombin complex concentrate mitigates diffuse bleeding after cardiopulmonary bypass in a porcine model

Background

Extracorporeal circuit priming and intravascular volume expansion during cardiopulmonary bypass (CPB) may lead to dilutional coagulopathy and excessive diffuse postoperative bleeding. Prothrombin complex concentrate (PCC) containing clotting factors II (FII), VII (FVII), IX (FIX), and X (FX) could be of potential value in correcting dilutional coagulopathy and reducing blood loss.

Methods

Anaesthetized pigs underwent CPB with hypothermia for 2 h at 25°C followed by 1 h of normothermia. Approximately 1 h after CPB, animals randomly received either isotonic saline 1 ml kg⁻¹ or PCC 30 IU kg⁻¹ in a volume of 1 ml kg⁻¹. Diffuse coagulopathic bleeding was assessed as suture hole blood loss from a Gore-Tex patch placed over a full-thickness incision in the left carotid artery.

Results

After CPB, levels of FII, FVII, FIX, and FX declined from baseline by 32% to 48%, and PCC fully or partially reversed those deficits. Median suture hole blood loss after administration of saline placebo was 74 ml. PCC reduced suture hole bleeding by a median of 54 ml with a 95% confidence interval of 6–112 ml (P=0.026) compared with saline. PCC, but not saline, normalized skin bleeding time. Peak thrombin generation markedly decreased after CPB, but then returned in PCC-treated animals to a level higher than baseline by 28.7 nM (14.5–41.1 nM; P=0.031).

Conclusions

PCC was effective in correcting dilutional coagulopathy and reducing diffuse bleeding in an in vivo large-animal CPB model. Further research is warranted on PCC as a haemostatic agent in CPB.

Ketamine delays mortality in an experimental model of hemorrhagic shock and subsequent sepsis

BACKGROUND

In previous studies ketamine was reported to improve survival and decrease serum interleukin-6 (IL-6) concentration after sepsis alone and after burn injury followed by sepsis. The aim of this study was to determine whether ketamine alters survival and/or IL-6 after hemorrhagic shock alone or hemorrhagic shock followed by sepsis.

MATERIALS AND METHODS

Rats were subjected to hemorrhagic shock with or without subsequent Gram-negative bacterial sepsis and were either treated with ketamine 5 mg/kg or were not treated. Blood was sampled for IL-6 determination prior to hemorrhage, at the completion of resuscitation, and at 6 and 30 h later. Mortality was recorded for 7 days following hemorrhage or hemorrhage+sepsis.

RESULTS

After hemorrhage+sepsis the time to median mortality was significantly later in the ketamine-treated group (36 h) than in the control group (12 h). At 12h the survival rate of the ketamine-treated group (100%) was significantly higher than in the control group (55%). There were no significant differences between groups with respect to IL-6 or 7-day survival after either hemorrhage+sepsis or hemorrhage alone.

CONCLUSION

Ketamine improved 12h survival and delayed mortality after hemorrhage+sepsis without significantly altering IL-6, and did not alter survival or IL-6 after hemorrhage alone.

Exsanguination in trauma: A review of diagnostics and treatment options

Trauma patients with haemorrhagic shock who only transiently respond or do not respond to fluid therapy and/or the administration of blood products have exsanguinating injuries. Recognising shock due to (exsanguinating) haemorrhage in trauma is about constructing a synthesis of trauma mechanism, injuries, vital signs and the therapeutic response of the patient. The aim of prehospital care of bleeding trauma patients is to deliver the patient to a facility for definitive care within the shortest amount of time by rapid transport and minimise therapy to what is necessary to maintain adequate vital signs. Rapid decisions have to be made using regional trauma triage protocols that have incorporated patient condition, transport times and the level of care than can be performed by the prehospital care providers and the receiving hospitals. The treatment of bleeding patients is aimed at two major goals: stopping the bleeding and restoration of the blood volume. Fluid resuscitation should allow for preservation of vital functions without increasing the risk for further (re)bleeding. To prevent further deterioration and subsequent exsanguinations 'permissive hypotension' may be the goal to achieve. Within the hospital, a sound trauma team activation system, including the logistic procedure as well as activation criteria, is essential for a fast and adequate response. After determination of haemorrhagic shock, all efforts have to be directed to stop the bleeding in order to prevent exsanguinations. A simultaneous effort is made to restore blood volume and correct coagulation. Reversal of coagulopathy with pharmacotherapeutic interventions may be a promising concept to limit blood loss after trauma. Abdominal ultrasound has replaced diagnostic peritoneal lavage for detection of haemoperitoneum. With the development of sliding-gantry based computer tomography diagnostic systems, rapid evaluation by CT-scanning of the trauma patient is possible during resuscitation. The concept of damage control surgery, the staged approach in treatment of severe trauma, has proven to be of vital importance in the treatment of exsanguinating trauma patients and is adopted worldwide. When performing 'blind' transfusion or 'damage control resuscitation', a predetermined fixed ratio of blood components may result in the administration of higher plasma and platelets doses and may improve outcome. The role of thromboelastography and thromboelastometry as point-of-care tests for coagulation in massive blood loss is emerging, providing information about actual clot formation and clot stability, shortly (10min) after the blood sample is taken. Thus, therapy guided by the test results will allow for administration of specific coagulation factors that will be depleted despite administration with fresh frozen plasma during massive transfusion of blood components.