Pathophysiology and treatment of coagulopathy in massive hemorrhage and hemodilution

In-vitro assessment of the effects of fibrinogen, recombinant factor VIIa and factor XIII on trauma-induced coagulopathy

: Trauma-induced coagulopathy (TIC) occurs commonly as a second event following severe injury. We evaluated the effects of fibrinogen, recombinant factor VIIa and factor XIII on blood clotting and fibrinolysis in an in-vitro TIC model. The TIC model included hemodilution, hyperfibrinolysis, acidosis and hypothermia. The extent of clot formation and fibrinolysis was evaluated using rotational thromboelastometry. Clot strength was increased following spiking the TIC blood with either 1.0 mg/ml fibrinogen, 3.0 μg/ml recombinant factor VIIa or 2.0 IU/ml factor XIII. Maximal effect was achieved by all agents in combination approximating the extent of clot formation to those in normal blood. Fibrinolysis was inhibited by factor XIII, while the reduction was stronger using all agents together. When each of the agents used in two times lower concentrations, clot strength was near to threshold. Fibrinogen and factor XIII but not factor VIIa exerted stimulation of clot strength, whereas synergistic effect of fibrinogen and factor XIII was observed. Maximal effect was achieved combining all agents. The antifibrinolytic effect was observed only by co-administration of fibrinogen, factor XIII and factor VIIa. On the basis of our study, we suggest that stimulation of clot formation and inhibition of fibrinolysis may be achieved by combination of FG, rFVIIa an FXIII using each of them at minimal effective concentration. Taken into consideration, multifactorial TIC pathogenesis, this approach may be preferable for improving coagulopathy than separate blood spiking with the essayed factors at high concentrations.

Controversies in the Clinical Practice of Patient Blood Management

Patient blood management (PBM) has been proposed as a standard of care in modern perioperative medicine. PBM-related interventions usually are implemented as bundles, but randomized controlled trials on the implementation of PBM as a bundle are missing. This special article focuses on the current evidence and controversies in the clinical practice of PBM and on emerging data related to specific PBM-related interventions in patients undergoing cardiac surgery. Strong evidence for many PBM-related interventions is limited because of missing studies or the poor quality of published findings and study endpoints. Restrictive blood transfusion and timely interventions to maintain hemoglobin concentration and to reduce blood loss potentially might result in improved patient outcome, although the latter has yet to be proven.

Massive Gastrointestinal Hemorrhage

Massive gastrointestinal hemorrhage is a life-threatening condition that can result from numerous causes and requires skilled resuscitation to decrease patient morbidity and mortality. Successful resuscitation begins with placement of large-bore intravenous or intraosseous access; early blood product administration; and early consultation with a gastroenterologist, interventional radiologist, and/or surgeon. Activate a massive transfusion protocol when initial red blood cell transfusion does not restore effective perfusion or the patient's shock index is greater than 1.0. Promptly reverse coagulopathies secondary to oral anticoagulant or antiplatelet use. Use thromboelastography or rotational thromboelastometry to guide further transfusions. Secure a definitive airway and minimize aspiration.

Viscoelastic testing in cardiac surgery

Bleeding complications are common in cardiac surgery and lead to an increase in morbidity and mortality. This is multifactorial in aetiology including the effects of cardiopulmonary bypass, the drugs given to manipulate the coagulation system and the vascular nature of the surgery itself. Viscoelastic tests provide a point of care, rapid assessment of coagulation which offer the advantage of faster turnaround times and a nuanced view of the elements of the coagulation system allowing targeted therapy to be delivered quickly. Both thomboelastography (TEG)and thromboelastometry (ROTEM) have been recommended for use in cardiac surgery, both have shown a reduction in transfusion and bleeding when used as part of a testing algorithm. They are particularly useful in assessing residual heparinisation and fibrinogen levels. Additionally, TEG allows the evaluation of the effects of anti-platelet agents on platelet function. This review discusses the mechanisms by which bleeding occurs in cardiac surgery and explores three uses of viscoelastic testing in cardiac surgery: to predict bleeding, to assess platelet function and peri-operative testing to reduce transfusion.

Point-of-Care Platelet Function Monitoring: Implications for Patients With Platelet Inhibitors in Cardiac Surgery

Although most physicians are comfortable managing the limited anticoagulant effect of aspirin, the recent administration of potent P2Y₁₂ receptor inhibitors in patients undergoing cardiac surgery remains a dilemma. Guidelines recommend discontinuation of potent P2Y₁₂ inhibitors 5- to- 7 days before surgery to reduce the risk of postoperative hemorrhage. Such a strategy might not be feasible before urgent surgery, due to ongoing myocardial ischemia or in patients at high risk for thromboembolic events. Recently, different point-of-care devices to assess functional platelet quality have become available for clinical use. The aim of this narrative review was to evaluate the implications and potential benefits of platelet function monitoring in guiding perioperative management and therapeutic options in patients treated with antiplatelets, including aspirin or P2Y₁₂ receptor inhibitors, undergoing cardiac surgery. No objective superiority of one point-of-care device over another was found in a large meta-analysis. Their accuracy and reliability are generally limited in the perioperative period. In particular, preoperative platelet function testing has been used to assess platelet contribution to bleeding after cardiac surgery. However, predictive values for postoperative hemorrhage and transfusion requirements are low, and there is a significant variability between and within these tests. Further, platelet function monitoring has been used to optimize the preoperative waiting period after cessation of dual antiplatelet therapy before urgent cardiac surgery. Furthermore, studies assessing their value in therapeutic decisions in bleeding patients after cardiac surgery are scarce. A general and liberal use of perioperative platelet function testing is not yet recommended.

Tracing the Lines: A Review of Viscoelastography for Emergency Medicine Clinicians

BACKGROUND

Viscoelastography (VE) is an established method to identify coagulopathies in various disease processes. Clinical decisions can be made with real-time tracings and quantitative values at the bedside. Thromboelastography (TEG®) and rotational thromboelastometry (ROTEM®) have been utilized in several disease states with clinical varying success.

OBJECTIVES

This review will summarize the literature and provide recommendations pertaining to major disease processes where VE may be beneficial, including trauma, anticoagulation reversal, liver disease, acute ischemic stroke, and acquired brain injuries.

DISCUSSION

VE has a role in many emergency medicine patients encountered by clinicians. Reduced mortality, decreased blood product utilization, and prognostication ability makes VE an intriguing tool that can be utilized by providers to improve patient care.

CONCLUSION

This review serves as a way for emergency medicine clinicians to utilize VE in their practice and provides an insightful literature overview.

Novel Treatment Strategy for Patients with Venom-Induced Consumptive Coagulopathy from a Pit Viper Bite

Pit viper venom commonly causes venom-induced consumptive coagulopathy (VICC), which can be complicated by life-threatening hemorrhage. VICC has a complex pathophysiology affecting multiple steps of the coagulation pathway. Early detection of VICC is challenging because conventional blood tests such as prothrombin time (PT) and activated partial thromboplastin time (aPTT) are unreliable for early-stage monitoring of VICC progress. As the effects on the coagulation cascade may differ, even in the same species, the traditional coagulation pathways cannot fully explain the mechanisms involved in VICC or may be too slow to have any clinical utility. Antivenom should be promptly administered to neutralize the lethal toxins, although its efficacy remains controversial. Transfusion, including fresh frozen plasma, cryoprecipitate, and specific clotting factors, has also been performed in patients with bleeding. The effectiveness of viscoelastic monitoring in the treatment of VICC remains poorly understood. The development of VICC can be clarified using thromboelastography (TEG), which shows the procoagulant and anticoagulant effects of snake venom. Therefore, we believe that TEG may be able to be used to guide hemostatic resuscitation in victims of VICC. Here, we aim to discuss the advantages of TEG by comparing it with traditional coagulation tests and propose potential treatment options for VICC.

A Retrospective Study of Transfusion Requirements in Trauma Patients Receiving Tranexamic Acid

The Military Application of Tranexamic Acid in Trauma Emergency Resuscitation Study (MATTERs) and Clinical Randomisation of an Antifibrinolytic in Significant Haemorrhage-2 (CRASH-2) studies demonstrate that tranexamic acid (TXA) reduces mortality in patients with traumatic hemorrhage. However, their results, conducted in foreign countries and U.S. military soldiers, provoke concerns over generalizability to civilian trauma patients in the United States. We report the evaluation of patient outcomes and transfusion requirements following treatment with TXA by a civilian air medical program. We conducted a retrospective chart review of trauma patients transported by air service to a Level 1 trauma center. For the purposes of intervention evaluation, patients meeting this criterion for the 2 years (2012-2014) prior to therapy implementation were compared with patients treated during the 2-year study period (2014-2016). Goals were to evaluate morbidity, mortality, transfusion requirements, and length of stay. During the review, 52 control (non-TXA) and 43 study (TXA) patients were identified as meeting inclusion criteria. Patients in the control group were found to be less acute, which correlated with shorter hospitals stays. There was reduced mortality for patients receiving TXA in spite of their increased acuity and decreased likelihood of survival. Trauma patients from this cohort study receiving TXA demonstrate decreased mortality in spite of increased acuity. This increased acuity is associated with increased transfusion requirements. Future research should evaluate patient selection with concern for fibrinolysis and provider bias. Randomized controlled trial is needed to evaluate the role of TXA administration in the United States.

Thromboelastometry assessment of the effects of fibrinogen, activated prothrombin complex concentrate, and tranexamic acid on clot formation and fibrinolysis in a model of trauma-induced coagulopathy

PURPOSE

Coagulation abnormalities are common following major trauma. The aim of this study was to assess the improvement of trauma-induced coagulopathy (TIC) in an in vitro model.

METHODS

TIC was created on blood taken from healthy individuals by inducing hemodilution, acidosis, hypothermia and fibrinolysis. Next, blood samples were subjected to rotational thromboelastometry to assess the effect of hemostasis modulators on blood coagulation and fibrinolysis.

RESULTS

Introducing to blood fibrinogen at 0.75 mg/mL, prothrombin complex concentrate at 0.66 IU/mL or tranexamic acid at 95 µg/mL increased clot strength. Higher effect was observed by combination of fibrinogen with tranexamic acid and prothrombin complex with tranexamic acid, whereas the maximal effect was achieved using all agents together. Fibrinolysis was inhibited by tranexamic acid and stronger by triple combination of the agents. Selective treating the TIC blood with fibrinogen, prothrombin complex or tranexamic acid at two time lower concentrations did not affect clot strength. Combining fibrinogen with prothrombin complex or with tranexamic acid stimulated clot strength but at lower extent compared to higher concentrations. Lysis onset time was prolonged by tranexamic acid. Maximal effect on both clot formation and fibrinolysis was achieved using all three agents together.

CONCLUSIONS

Blood clotting stimulation and fibrinolysis inhibition in the TIC model was enough combining subthreshold concentrations of fibrinogen, prothrombin complex and tranexamic acid. Further experiments are warranted in both in vitro and in vivo conditions with minimally effective concentrations of both pro-coagulant and anti-fibrinolytic drugs assuming that this combinatorial approach may not only improve coagulopathy but also minimize the risk of thrombotic complications.

Association of Timing of Plasma Transfusion With Adverse Maternal Outcomes in Women With Persistent Postpartum Hemorrhage

IMPORTANCE

Early plasma transfusion for women with severe postpartum hemorrhage (PPH) is recommended to prevent coagulopathy. However, there is no comparative, quantitative evidence on the association of early plasma transfusion with maternal outcomes.

OBJECTIVE

To compare the incidence of adverse maternal outcomes among women who received plasma during the first 60 minutes of persistent PPH vs women who did not receive plasma for similarly severe persistent PPH.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter cohort study used a consecutive sample of women with persistent PPH, defined as PPH refractory to first-line measures to control bleeding, between January 1, 2011, and January 1, 2013. Time-dependent propensity score matching was used to select women who received plasma during the first 60 minutes of persistent PPH and match each of them with a woman who had shown the same severity and received the same treatment of PPH but who had not received plasma at the moment of matching. Transfusions were not guided by coagulation tests. Statistical analysis was performed from June 2018 to June 2019.

EXPOSURES

Transfusion of plasma during the first 60 minutes of persistent PPH vs no or later plasma transfusion.

MAIN OUTCOMES AND MEASURES

Incidence of adverse maternal outcomes, defined as a composite of death, hysterectomy, or arterial embolization.

RESULTS

This study included 1216 women (mean [SD] age, 31.6 [5.0] years) with persistent PPH, of whom 932 (76.6%) delivered vaginally and 780 (64.1%) had PPH caused by uterine atony. Seven women (0.6%) died because of PPH, 62 women (5.1%) had a hysterectomy, and 159 women (13.1%) had arterial embolizations. Among women who received plasma during the first 60 minutes of persistent PPH, 114 women could be matched with a comparable woman who had not received plasma at the moment of matching. The incidence of adverse maternal outcomes was similar between the women, with adverse outcomes recorded in 24 women (21.2%) who received early plasma transfusion and 23 women (19.9%) who did not receive early plasma transfusion (odds ratio, 1.09; 95% CI, 0.57-2.09). Results of sensitivity analyses were comparable to the primary results.

CONCLUSIONS AND RELEVANCE

In this cohort study, initiation of plasma transfusion during the first 60 minutes of persistent PPH was not associated with adverse maternal outcomes compared with no or later plasma transfusion, independent of severity of PPH.

Four-factor Prothrombin Complex Concentrate for the Management of Patients Receiving Direct Oral Activated Factor X Inhibitors

Factor Xa inhibitors prevent thrombosis but are associated with severe or life-threatening bleeding. Here, the authors present data on four-factor prothrombin complex concentrates in management of anticoagulation-associated bleeding and restoring hemostasis, including recent results from the UPRATE study.

Consensus Report on Patient Blood Management in Cardiac Surgery by Turkish Society of Cardiovascular Surgery (TSCVS), Turkish Society of Cardiology (TSC), and Society of Cardio-Vascular-Thoracic Anaesthesia and Intensive Care (SCTAIC)

Anemia, transfusion and bleeding independently increase the risk of complications and mortality in cardiac surgery. The main goals of patient blood management are to treat anemia, prevent bleeding, and optimize the use of blood products during the perioperative period. The benefit of this program has been confirmed in many studies and its utilization is strongly recommended by professional organizations. This consensus report has been prepared by the authors who are the task members appointed by the Turkish Society of Cardiovascular Surgery, Turkish Society of Cardiology (TSC), and Society of Cardio-Vascular-Thoracic Anaesthesia and Intensive Care to raise the awareness of patient blood management. This report aims to summarize recommendations for all perioperative blood- conserving strategies in cardiac surgery.

Thromboelastometric evaluation of coagulation profiles of cold-stored autologous whole blood: A prospective observational study

Preoperative autologous blood donation is a well-established procedure to reduce the need for allogeneic blood transfusion. We hypothesized that coagulation activity is maintained in cold-stored whole blood, because the fundamental polymerization properties of fibrin are preserved.Fifty adult patients who underwent elective cardiothoracic surgery were enrolled.Autologous whole blood collected 2 to 4 times at almost 1-week intervals before surgery was stored at approximately 4°C until reinfusion at the time of surgery. Blood samples were drawn just before reinfusion, and rotational thromboelastometry variables and fibrinogen levels were measured.A total of 158 samples were analyzed. The mean duration of cold storage was 16.7 ± 7.4 days (range: 6-33 days). Platelet counts were very low due to collection through a leukoreduction filter. The mean fibrinogen level was 2.3 ± 0.6 g/L. Amplitude at 10 minutes after CT (A10), amplitude at 20 minutes after CT (A20), and maximum clot firmness (MCF) values as determined by FIBTEM analysis were 10.8 ± 3.8, 12.2 ± 4.2, and 13.1 ± 4.7 mm, respectively. Fibrinogen levels were strongly correlated with A10, A20, and FIBTEM-MCF values (ρ = 0.83, P < .0001, ρ = 0.84, P < .0001, ρ = 0.85, P < .0001, respectively). Fibrinogen levels were not correlated with the duration of cold storage (ρ = 0.06, P = .43).The results of the present study demonstrate that fibrin polymerization occurs in cold-stored autologous whole blood, and that such activity is strongly correlated with fibrinogen levels. Furthermore, our data suggest that cold-stored leukoreduced autologous whole blood retains fibrin polymerization properties throughout 33 days.

Functional Coagulation Differences Between Lobar and Deep Intracerebral Hemorrhage Detected by Rotational Thromboelastometry: A Pilot Study

BACKGROUND

Lobar intracerebral hemorrhage (ICH) is known to have better clinical outcomes and preliminary evidence of less hematoma expansion compared to deep ICH. No functional coagulation differences between lobar and deep ICH have been identified using traditional plasma-based coagulation tests. We investigated for coagulation differences between lobar and deep ICH using whole-blood coagulation testing (Rotational Thromboelastometry: [ROTEM]).

METHODS

Clinical, radiographic, and laboratory data were prospectively collected for primary ICH patients enrolled in a single-center ICH study. Patients with preceding anticoagulant use or admission coagulopathy on traditional laboratory testing were excluded. Lobar and deep ICH patients receiving admission ROTEM were analyzed. Linear regression was used to assess the association of ICH location with coagulation test results after adjusting for potential confounders.

RESULTS

There were 12 lobar and 19 deep ICH patients meeting inclusion criteria. Lobar ICH patients were significantly older and predominantly female. Lobar ICH had faster intrinsic pathway coagulation times (139.8 vs 203.2 s; 95% CI - 179.91 to - 45.96; p = 0.002) on ROTEM testing compared to deep ICH after adjusting for age, sex, and hematoma volume. This revealed functional coagulation differences, specifically quicker clot formation in lobar compared to deep ICH. No differences were noted using traditional coagulation testing (prothrombin time/partial thromboplastin time/platelet count).

CONCLUSIONS

Our pilot data may suggest that there are functional coagulation differences between lobar and deep ICH identified using ROTEM. Whole-blood coagulation testing may be useful in assessing coagulopathy in ICH patients and in determining reversal treatment paradigms, though further work is needed.

Blood Products in the Management of Abnormal Placentation

A critical tool in the successful management of patients with abnormal placentation is an established massive transfusion protocol designed to rapidly deliver blood products in obstetrical and surgical hemorrhage. Spurred by trauma research and an understanding of consumptive coagulopathy, the past 2 decades have seen a shift in volume resuscitation from an empiric, crystalloid-based method to balanced, targeted transfusion therapy. The present article reviews patient blood management in abnormal placentation, beginning with optimizing the patient's status in the antenatal period to the laboratory assessment and transfusion strategy for blood products at the time of hemorrhage.

Laboratory Monitoring and Transfusion Guidelines to Influence Care in Patients Undergoing Multilevel Spinal Fusion Surgery

PURPOSE

The purpose of this project was to determine whether the use of the modified Northwestern high risk spine protocol in patients undergoing multilevel spinal fusion surgery would result in improved transfusion practices.

DESIGN

Preimplementation and postimplementation design.

METHODS

A laboratory monitoring and transfusion guideline protocol was implemented in patients undergoing multilevel spinal fusions. Data were collected via a manual retrospective chart review of the electronic medical record before and after implementation of the protocol.

FINDINGS

Laboratory values were monitored at guided intervals. There was a statistically significant (P = .004) decrease in the mean hemoglobin value at which a packed red blood cell transfusion was initiated.

CONCLUSIONS

Through the use of the protocol, laboratory value monitoring provided quantitative data to aid and improve clinical decision making for practitioners in the perioperative period.

Fluid resuscitation during persistent postpartum haemorrhage and maternal outcome: A nationwide cohort study

OBJECTIVE

To determine the association between increasing volumes of crystalloids and colloids administered before transfusion of packed red blood cells in women with persistent postpartum haemorrhage and adverse maternal outcomes.

STUDY DESIGN

Retrospective cohort study in the Netherlands. Women with persistent postpartum haemorrhage and known clear fluids volume for resuscitation were included. Women who received ≤2 L of clear fluids were the reference group. We determined the effect of every additional litre of clear fluids on total blood loss, severe maternal morbidity and mortality. Results were adjusted for patient and bleeding characteristics.

RESULTS

Of the 883 included women, 199 received ≤2 L of clear fluids. Median blood loss for the reference group was 2.9 L (interquartile range 2.2-3.4). Adjusted mean difference in blood loss compared with the reference group was 0.2 L (95% confidence interval -0.1 to 0.5) for women in the >2 to ≤3 L, 0.4 L (0.1-0.7) for the >3 to ≤4 L category, 0.6 L (0.5-0.7) for the >4 to ≤5 L category, and 1.9 L (1.5-2.3) for the >5 to ≤7 L category. Adjusted odds ratios for adverse maternal outcomes were 1.0 (0.7-1.6), 1.2 (0.8-1.9), 1.8 (1.1-3.1) and 4.4 (2.6-7.5) for women in the 2 to ≤3 L category, >3 to ≤4 L, >4 to ≤5 L, and >5 to ≤7 L volume categories respectively. Results were similar in strata of different severities of bleeding.

CONCLUSION

Clear fluids volume >4 L was independently associated with adverse maternal outcome in women with persistent postpartum haemorrhage.

Transfusion strategies for major haemorrhage in trauma

Trauma is a leading cause of death worldwide in persons under 44 years of age, and uncontrolled haemorrhage is the most common preventable cause of death in this patient group. The transfusion management of trauma haemorrhage is unrecognisable from 20 years ago. Changes in clinical practice have been driven primarily by an increased understanding of the pathophysiology of trauma-induced coagulopathy (TIC), which is associated with poor clinical outcomes, including a 3- to 4-fold increased risk of death. Targeting this coagulopathy alongside changes to surgical and anaesthetic practices (an overarching strategy known as damage control surgery/damage control resuscitation) has led to a significant reduction in mortality rates over the last two decades. This narrative review will discuss the transfusion practices that are currently used for trauma haemorrhage and the evidence that supports these practices.

Recombinant activated factor VII (rFVIIa) in refractory haemorrhage for non-haemophiliacs: an eleven-year single-centre experience

Background

Massive bleeding is one of the commonest salvageable causes of death. The search for an ideal haemostatic agent during massive bleeding is still ongoing. One of the novel haemostatic medications is recombinant activated factor VII (rFVIIa). To date, the usage of rFVIIa during massive haemorrhage among non-haemophiliac patients remains off-label. The aim of this study is to report our experience in using rFVIIa to treat refractory bleeding.

Methods

Medical records of all patients treated with rFVIIa for massive bleeding over an eleven-year period in a single institution were recorded. Treatment indications, 24-h and 30-day mortality, changes in transfusion needs and coagulation profiles after rFVIIa administration were analysed.

Results

rFVIIa were administered in 76 patients. Of these, 41 (53.9%) were non-surgical bleeding, followed by 22 patients (28.9%) with trauma, other surgery bleedings in 9 patients (11.8%) and 4 patients (5.4%) with peripartum haemorrhage. Total survival rate was 78.9% within 24 h and 44.7% over 30 days. Among all these patients who had received rFVIIa due to life-threatening haemorrhage, blood and blood product requirements were significantly reduced (P < 0.001), and the coagulation profiles improved significantly (P < 0.05). Two patients with preexisting thromboembolism were given rFVIIa due to intractable bleeding, both survived. No thromboembolic events were reported after the administration of rFVIIa.

Conclusions

rFVIIa significantly improved coagulation parameters and reduced blood product requirements during refractory haemorrhage. Additionally, usage of rFVIIa in trauma and peripartum haemorrhage patients yield better outcomes than other groups of patients. However, the overall mortality rate remained high.

Prohemostatic Activity of Factor X in Combination With Activated Factor VII in Dilutional Coagulopathy

BACKGROUND

Recombinant activated factor VII (rFVIIa) concentrate reduces allogeneic blood transfusions, but it may increase thromboembolic complications in complex cardiac surgery. The mixture of activated factor VII (FVIIa) and factor X (FX) (FVIIa/FX) (FVIIa:FX = 1:10) is a novel bypassing agent for hemophilia patients. We hypothesized that the combination of FX and FVIIa could improve thrombin generation (TG) in acquired multifactorial coagulation defects such as seen in cardiac surgery and conducted in vitro evaluation of FVIIa/FX in parallel with other coagulation factor concentrates using in vitro and in vivo diluted plasma samples.

METHODS

Plasma samples were collected from 9 healthy volunteers and 12 cardiac surgical patients. We measured TG (Thrombinoscope) using in vitro 50% dilution plasma and in vivo dilution plasma after cardiopulmonary bypass, in parallel with thromboelastometry (ROTEM) and standard coagulation assays. In vitro additions of FVIIa/FX (0.35, 0.7, and 1.4 μg/mL, based on the FVIIa level), rFVIIa (1.4, 2.8, and 6.4 μg/mL), prothrombin complex concentrate (0.3 international unit), and 20% plasma replacement were evaluated.

RESULTS

In diluted plasma, the addition of either FVIIa/FX or rFVIIa shortened the lag time and increased the peak TG, but the effect in lag time of FVIIa/FX at 0.35 μg/mL was more extensive than rFVIIa at 6.4 μg/mL. Prothrombin complex concentrate increased peak TG by increasing the prothrombin level but failed to shorten the lag time. No improvement in any of the TG variables was observed after 20% volume replacement with plasma. The addition of factor concentrates normalized prothrombin time/international normalized ratio but not with plasma replacement. In cardiac patients, similar patterns were observed on TG in post-cardiopulmonary bypass samples. FVIIa/FX shortened clotting time (CT) in a concentration-dependent manner on CT on thromboelastometry. Plasma replacement did not improve CT, but a combination of plasma and FVIIa/FX (0.35 μg/mL) more effectively shortened CT than FVIIa/FX alone.

CONCLUSIONS

The combination of FVIIa and FX improved TG more efficiently than rFVIIa alone or plasma in dilutional coagulopathy models. The required FVIIa dose in FVIIa/FX was considerably lower than those reported during bypassing therapy in hemophilia patients (1.4-2.8 μg/mL). The combination of plasma could restore coagulation more efficiently compared to FVIIa/FX alone. Lesser FVIIa requirement to exert procoagulant activity may be favorable in terms of reducing systemic thromboembolic complications.

Management of postpartum hemorrhage: how to improve maternal outcomes?

Postpartum hemorrhage is the leading cause of maternal mortality and severe morbidity. Despite efforts to improve maternal outcomes, management of postpartum hemorrhage still faces at least four challenges, discussed in this review. First, current definitions for severe postpartum hemorrhage hamper early identification of women with a high risk of adverse outcomes. Adaptations to the definitions and the use of clinical tools such as shock index and early warning systems may facilitate this early identification. Second, surgical and radiological interventions to prevent hysterectomy are not always successful. More knowledge on the influence of patient and bleeding characteristics on the success rates of these interventions is necessary. Scarce data suggest that early timing of intrauterine balloon tamponade may improve maternal outcomes, whereas early timing of arterial embolization seems to be unrelated to maternal outcomes. Third, fluid resuscitation with crystalloids and colloids is unavoidable in the early phases of postpartum hemorrhage but may result in dilutional coagulopathy. Effects of different volumes of clear fluids on the occurrence of dilutional coagulopathy and maternal outcomes is unknown. Fourth, a better understanding of diagnosis and correction of coagulopathy during postpartum hemorrhage is needed. Low plasma fibrinogen levels at the start of postpartum hemorrhage predict progression to severe hemorrhage, but standard coagulation screens are time consuming. A solution may be point-of-care coagulation testing; however, clinical usefulness during postpartum hemorrhage has not been demonstrated. To date, early administration of tranexamic acid is the only hemostatic intervention that was proven to improve outcomes in women with postpartum hemorrhage.

Perioperative bleeding management in pediatric patients

PURPOSE OF REVIEW

Managing the bleeding pediatric patient perioperatively can be extremely challenging. The primary goals include avoiding hypotension, maintaining adequate tissue perfusion and oxygenation, and maintaining hemostasis. Traditional bleeding management has consisted of transfusion of autologous blood products, however, there is strong evidence that transfusion-related side-effects are associated with increased morbidity and mortality in children. Especially concerning is the increased reported incidence of noninfectious adverse events such as transfusion-related acute lung injury, transfusion-related circulatory overload and transfusion-related immunomodulation. The current approach in perioperative bleeding management of the pediatric patient should focus on the diagnosis and treatment of anemia and coagulopathy with the transfusion of blood products only when clinically indicated and guided by goal-directed strategies.

RECENT FINDINGS

Current guidelines recommend that a comprehensive multimodal patient blood management strategy is critical in optimizing patient care, avoiding unnecessary transfusion of blood and blood product and limiting transfusion-related side-effects.

SUMMARY

This article will highlight current guidelines in perioperative bleeding management for our most vulnerable pediatric patients with emphasis on individualized targeted intervention using point-of-care testing and specific coagulation products.

Evaluation of the hemocompatibility of RADA 16-I peptide

RADA 16-I is an ionic self-assembling peptide that can form macroscopic scaffolds through β-sheet structures which are used in favor of cell growth and tissue engineering. This peptide has also the ability to stop bleeding effectively and quickly (∼20 seconds) when applied directly to the injuries. This study is focused on coagulation process, platelet aggregation, C3 and C4 concentrations, CBC counting, hemolysis, and white blood cell morphology tests to analyze hemocompatibility of RADA 16-I at different concentrations - 0.1, 0.2, 0.3 and 0.5%. According to the results, RADA 16-I hydrogel decreased the number of blood cells, slightly increased clot formation time and platelet aggregation, and yielded negligible hemolysis and only small changes in C3 and C4 concentrations and white blood cell morphology. All by all, the in vitro tests of hemocompatibility showed no perturbation in the blood composition when the peptides were in contact with the blood. The observed rapid hemostasis might be a result of increasing local concentrations of molecules involved in the formation of clot near the peptide hydrogel, thereby making a barrier which ended up with complete hemostasis. In conclusion, our experiments strongly supported further development of biomaterials based on RADA 16-I peptide.

Use of thrombin generation test for monitoring hemostasis in coronary bypass surgery

To evaluate the parameters of the thrombin generation test (TGT) in coronary artery disease (CAD) patients on prolonged aspirin therapy during on-pump coronary artery bypass grafting (CABG) after donor platelet concentrate transfusion. A total of 148 patients with CAD on prolonged aspirin therapy (75–100 mg/day) who have undergone elective on-pump CABG were consecutively included in the study. Patients were divided randomly into two groups. Group 1 (n = 76) received donor platelet transfusions after cardiopulmonary bypass, whereas Group 2 (n = 72) did not. TGT parameters were measured using an analyzer at pre-, intra-, and early postoperative periods. Activation of the endogenous thrombin potential was observed in patients on prolonged aspirin therapy in the pre- and intraoperative periods, as confirmed by high peak thrombin and increased velocity index. The activation time of the prothrombinase complex and thrombin generation time were greater than the control group. The blood hemostatic potential in patients who did not receive transfusions in the early postoperative period decreased up to the level of the control group in the extended time parameters. Hemostatic potential in plasma in patients on aspirin was preserved. Given the laboratory test results and clinical data, platelet concentrate transfusion is unnecessary for prevention.

Optical sensing of anticoagulation status: Towards point-of-care coagulation testing

Anticoagulant overdose is associated with major bleeding complications. Rapid coagulation sensing may ensure safe and accurate anticoagulant dosing and reduce bleeding risk. Here, we report the novel use of Laser Speckle Rheology (LSR) for measuring anticoagulation and haemodilution status in whole blood. In the LSR approach, blood from 12 patients and 4 swine was placed in disposable cartridges and time-varying intensity fluctuations of laser speckle patterns were measured to quantify the viscoelastic modulus during clotting. Coagulation parameters, mainly clotting time, clot progression rate (α-angle) and maximum clot stiffness (MA) were derived from the clot viscoelasticity trace and compared with standard Thromboelastography (TEG). To demonstrate the capability for anticoagulation sensing in patients, blood samples from 12 patients treated with warfarin anticoagulant were analyzed. LSR clotting time correlated with prothrombin and activated partial thromboplastin time (r = 0.57-0.77, p<0.04) and all LSR parameters demonstrated good correlation with TEG (r = 0.61-0.87, p<0.04). To further evaluate the dose-dependent sensitivity of LSR parameters, swine blood was spiked with varying concentrations of heparin, argatroban and rivaroxaban or serially diluted with saline. We observed that anticoagulant treatments prolonged LSR clotting time in a dose-dependent manner that correlated closely with TEG (r = 0.99, p<0.01). LSR angle was unaltered by anticoagulation whereas TEG angle presented dose-dependent diminution likely linked to the mechanical manipulation of the clot. In both LSR and TEG, MA was largely unaffected by anticoagulation, and LSR presented a higher sensitivity to increased haemodilution in comparison to TEG (p<0.01). Our results establish that LSR rapidly and accurately measures the response of various anticoagulants, opening the opportunity for routine anticoagulation monitoring at the point-of-care or for patient self-testing.

Management of severe perioperative bleeding: guidelines from the European Society of Anaesthesiology: First update 2016

: The management of perioperative bleeding involves multiple assessments and strategies to ensure appropriate patient care. Initially, it is important to identify those patients with an increased risk of perioperative bleeding. Next, strategies should be employed to correct preoperative anaemia and to stabilise macrocirculation and microcirculation to optimise the patient's tolerance to bleeding. Finally, targeted interventions should be used to reduce intraoperative and postoperative bleeding, and so prevent subsequent morbidity and mortality. The objective of these updated guidelines is to provide healthcare professionals with an overview of the most recent evidence to help ensure improved clinical management of patients. For this update, electronic databases were searched without language restrictions from 2011 or 2012 (depending on the search) until 2015. These searches produced 18 334 articles. All articles were assessed and the existing 2013 guidelines were revised to take account of new evidence. This update includes revisions to existing recommendations with respect to the wording, or changes in the grade of recommendation, and also the addition of new recommendations. The final draft guideline was posted on the European Society of Anaesthesiology website for four weeks for review. All comments were collated and the guidelines were amended as appropriate. This publication reflects the output of this work.

Effect of Hemodilution In Vitro with Hydroxyethyl Starch on Hemostasis

Background

Hydroxyethyl starch (HES) solutions are used for volume expansion during surgery. We aimed to investigate how 6%HES 130/0.4 affects hemostasis.

Material/Methods

Blood samples were collected from 12 healthy adult volunteers, diluting with 6%HES 130/0.4 (HES group) or Ringer lactate solution (RL control group). The hemodilution ratio (HR) of citrated blood volume to plasma substitute volume was 10: 0 (undiluted), 10: 2, 10: 4, and 10: 6. Clotting factors activity was measured. Thrombin generation was monitored. Platelet function was analyzed.

Results

1) Activity of coagulation factor was decreased with increasing HR compared to undiluted baseline, and the activity of FVIII was significantly decreased in HES vs. RL. 2) Calibrated automated thrombography (CAT) results showed HES extended lag time, time to peak (ttpeak), start tail, and decreased peak of thrombin generation. Although lag time and ttpeak were significantly prolonged in HES vs. RL, endogenous thrombin potential (ETP) did not change. 3) Flow cytometric (FCM) analysis showed that HES reduced platelet phospholipids serine (PS) vs. baseline and RL. 4) HES significantly decreased antithrombin activity (AT: A) of the anticoagulant system with increasing HR vs. baseline and RL. 5) For fibrinolytic system, HES did not affect fibrinogen degradation products (FDP) and D-dimers (D-D) vs. baseline, or α₂-antiplasmin (α2-AP) vs. RL.

Conclusions

By reducing FVIII activity and platelet PS expression, HES interfered with PS combining to FXIa, FVIIIa, and FVa, which affected the acceleration and explosion stage of thrombin. The decreased velocity and peak of thrombin generation delays and reduces clot formation. Combined 6%HES 130/0.4 decreased anticoagulant activity and may have clinical utility.

Thromboelastometry guided fibrinogen replacement therapy in cardiac surgery: a retrospective observational study

This retrospective, observational study compared the impact of a point-of-care rotational thromboelastometry (ROTEM®) method versus conventional bleeding management in terms of postoperative (24-h) blood loss, intraoperative and postoperative (24-h) transfusion requirement and length of stay in the postoperative intensive care unit (ICU) in patients undergoing cardiac surgery. Forty consecutive patients undergoing cardiac surgery under ROTEM®-guided hemostatic management were enrolled; the control population included 40 selected patients undergoing similar interventions without ROTEM® monitoring. Significantly more patients in the thromboelastometry group versus the control group received fibrinogen (45 vs 10 %; p < 0.0001), while fewer received a transfusion (40 vs 72.5 %; p < 0.0033). Compared with control group patients, those in the thromboelastometry group had less postoperative bleeding (285 vs 393 mL; p < 0.0001), a shorter time from cardiopulmonary bypass discontinuation to skin suture (79.3 vs 92.6 min; p = 0.0043) and a shorter stay in the ICU (43.7 vs 52.5 h; p = 0.0002). In our preliminary experience, ROTEM®-guided bleeding management was superior to conventional management of bleeding in patients undergoing complex cardiac surgery with cardiopulmonary bypass in terms of reduced postoperative blood loss, transfusion requirement, and length of ICU stay.

Performance of functional fibrinogen thromboelastography in children undergoing congenital heart surgery

BACKGROUND

Functional Fibrinogen assay of the Thromboelastography (FFTEG), a whole blood viscoelastic hemostatic assay, has been used to estimate fibrinogen levels in adult patients undergoing major surgery but its performance in pediatric patients undergoing cardiac surgery requires evaluation. In this study, we evaluate the correlation between FFTEG parameters and standard laboratory tests for fibrinogen and platelet counts before and after cardiopulmonary bypass in children undergoing repair for congenital heart disease.

METHODS

In this prospective observational study, whole blood samples were obtained from children less than 5 years of age undergoing congenital heart surgery with cardiopulmonary bypass before surgical incision and immediately after administration of protamine. Blood samples were analyzed for Thromboelastography, Functional Fibrinogen level measured by FFTEG (FLEV), complete blood counts with platelet count and plasma fibrinogen assay (LFib, Clauss). The primary outcome of this study was to assess the correlation between FFTEG parameters, LFib and platelet counts in neonates, infants, and small children less than 5 years old. Additionally, we studied if postbypass FFTEG parameters could predict critical thresholds of hypofibrinogenemia LFib ≤200 mg·dl^-1 .

RESULTS

One hundred and five children (22 neonates, 51 infants, and 32 small children) were included in the final analysis. FLEV estimated higher fibrinogen levels than LFib in all patients. Before bypass, FLEV was on average 133 mg·dl^-1 higher than LFib (95% confidence interval, CI, 116-150, P < 0.001) for all the patients; after bypass, FLEV was 48 mg·dl^-1 (95% CI: 37-59, P < 0.001) higher than LFib for all the patients. Linear correlation coefficients between FLEV and LFib in all patients were R = 0.41 (95% CI: 0.24-0.56, P < 0.001) before bypass and increased to R = 0.63 (95% CI: 0.51-0.74, P < 0.001) after bypass. Bland Altman analysis performed on postbypass values of FLEV and LFib showed a positive bias of FLEV in estimation of LFib. The magnitude and the variability of the bias for all the patients group was decreased with lower mean of the difference of FLEV and LFib when the average values of FLEV and LFib were <200 mg·dl^-1 . Low linear correlations were noticed between maximal amplitude of platelet contribution to FFTEG and platelet counts both before and after bypass. For predicting the clinical thresholds of postbypass hypofibrinogenemia at plasma fibrinogen levels ≤200 mg·dl^-1 , FLEV and maximal amplitude of the fibrinogen clot generated area under receiver operative curves at 0.90 (95% CI = 0.76-1.0) in neonates, 0.6 (95% CI- 0.42-0.78) in infants, and 0.97 (95% CI = 0.91-1.0) in small children. Based on the receiver operative curves, values of postbypass hypofibrinogenemia with LFib ≤200 g·dl^-1 corresponded to cutoffs of FLEV_POST ≤245 mg·dl^-1 and maximal amplitude of the fibrinogen clot ≤13.4 mm.

CONCLUSION

In pediatric patients undergoing cardiac surgery, FLEV derived from Functional Fibrinogen correlated linearly with plasma fibrinogen levels (Clauss) both before and after CPB. FLEV estimation of plasma fibrinogen was improved after CPB in neonates, infants, and small children. After CPB, FFTEG can be used to predict laboratory diagnosis of critical hypofibrinogenemia (≤200 mg·dl^-1 ) during pediatric cardiac surgery. Further studies are required to assess the impact of predictability of FFTEG on component transfusion during pediatric cardiac surgery.

Monitoring the coagulation status of trauma patients with viscoelastic devices

Coagulopathy is a physiological response to massive bleeding that frequently occurs after severe trauma and is an independent predictive factor for mortality. Therefore, it is very important to grasp the coagulation status of patients with severe trauma quickly and accurately in order to establish the therapeutic strategy. Judging from the description in the European guidelines, the importance of viscoelastic devices in understanding the disease condition of patients with traumatic coagulopathy has been widely recognized in Europe. In the USA, the ACS TQIP Massive Transfusion in Trauma Guidelines proposed by the American College of Surgeons in 2013 presented the test results obtained by the viscoelastic devices, TEG® 5000 and ROTEM®, as the standard for transfusion or injection of blood plasma, cryoprecipitate, platelet concentrate, or anti-fibrinolytic agents in the treatment strategy for traumatic coagulopathy and hemorrhagic shock. However, some studies have reported limitations of these viscoelastic devices. A review in the Cochrane Library published in 2015 pointed out the presence of biases in the abovementioned reports in trauma patients and the absence of a quality study in this field thus far. A quality study on the relationship between traumatic coagulopathy and viscoelastic devices is needed.