Protocolised thromboelastometric-guided haemostatic management in patients with traumatic brain injury: a pilot study.

Coagulopathy in patients with traumatic brain injury is associated with an increase in morbidity and mortality. Although timely and aggressive treatment of coagulopathy is of paramount importance, excessive transfusion of blood products has been linked with poor long-term outcomes in patients with traumatic brain injury. A point-of-care thromboelastometric-guided algorithm could assist in creating a more individually tailored approach to each patient. The aim of this study was to evaluate the feasibility of implementing a thromboelastometric-guided algorithm in centres that were formerly naïve to thromboelastometry. Hence, we developed such an algorithm and provided training to four centres across Europe to direct the haemostatic management of patients with severe traumatic brain injury. The primary outcome was adherence to the algorithm and timing of the availability of relevant results. Thirty-two patients were included in the study. Complete adherence to the algorithm was observed in 20 out of 32 cases. The availability of thromboelastometric results after hospital admission was reported significantly earlier than conventional coagulation tests (median (IQR [range]) 33 (20-40 [14-250]) min vs. 71 (51-101 [32-290]) min; p = 0.037). Although only 5 out of 32 patients had abnormalities of conventional coagulation tests, 21 out of 32 patients had a coagulopathic baseline thromboelastometric trace. Implementing a thromboelastometric-guided algorithm for the haemostatic therapy of traumatic brain injury is feasible in centres formerly naïve to this technology and may lead to more rapid and precise coagulation management. Further large-scale studies are warranted to confirm the results of this pilot trial and evaluate clinical outcomes.

A comparison of the new ROTEM® sigma with its predecessor, the ROTEMdelta.

Thromboelastometry point-of-care coagulation testing facilitates optimised management of bleeding. Previous thromboelastometry systems required the blood sample and liquid reagents to be pipetted in several manual steps by trained personnel. The ROTEMsigma coagulation analyser is a fully automated point-of-care device. We aimed to assess the reference ranges of the new device and to compare the results with those of the predecessor device, the ROTEMdelta. We took blood from healthy volunteers and from hyper- or hypocoagulable patients; blood samples from healthy volunteers served to determine reference ranges for the most important parameters for the ROTEMsigma: CTEXTEM 48-61 s; A5EXTEM 30-51 mm; MCFEXTEM 54-70 mm; CTINTEM 138-174 s; MCFINTEM 51-67 mm and MCFFIBTEM 5-24 mm. We then used blood samples from patients to compare the results obtained between the old and the new device. We found a strong correlation between the same tests performed on two ROTEMsigma devices and between the ROTEMsigma and the ROTEMdelta with respect to the determination of thromboelastometry parameters of hyper- and hypocoagulable patients (all p < 0.001 and R > 0.8). Performance evaluation for the ROTEMsigma device showed very high precision (R > 0.99, p < 0.001). Our reference ranges can serve as an important aid for other hospitals using this new device.

Bleeding risk assessment in patients undergoing elective cardiac surgery using ROTEM(®) platelet and Multiplate(®) impedance aggregometry.

Impaired platelet function is a major risk factor for peri-operative bleeding and transfusion. This prospective, observational study enrolled 101 consecutive patients undergoing elective cardiac surgery with cardiopulmonary bypass. Platelet function was assessed by two whole blood impedance aggregometers (ROTEM(®) platelet and Multiplate(®) ), using three different activators (arachidonic acid, adenosine diphosphate and thrombin receptor-activating peptide-6), at three peri-operative time points (before anaesthesia, after aortic declamping and 5-10 min after protamine administration). Platelet function was impaired over the time-course in all assays. Results after protamine administration demonstrated the best correlation with postoperative chest tube drainage. Patients with a chest tube drainage exceeding the 75th percentile of the entire study population, during the first 24 postoperative hours, were characterised to have excessive bleeding. Both devices provided similar predictability for postoperative chest tube drainage and red blood cell transfusion requirements. The latter was associated with the degree of platelet inhibition and the number of pathways inhibited determined respective cut-off values.

Fast interpretation of thromboelastometry in non-cardiac surgery: reliability in patients with hypo-, normo-, and hypercoagulability.

BACKGROUND: Conventional coagulation test are not useful to guide haemostatic therapy in severe bleeding due to their long turn-around time. In contrast, early variables assessed by point-of-care thromboelastometry (ROTEM(®)) are available within 10-20 min and increasingly used to guide haemostatic therapy in liver transplantation and severe trauma. However, the reliability of early ROTEM(®) variables to predict maximum clot firmness (MCF) in non-cardiac surgery patients with subnormal, normal, and supranormal MCF has not yet been evaluated. METHODS: Retrospective data of 14,162 ROTEM(®) assays (3939 EXTEM(®), 3654 INTEM(®), 3287 FIBTEM(®), and 3282 APTEM(®) assays) of patients undergoing non-cardiac surgery were analysed. ROTEM(®) variables [clotting time (CT), clot formation time (CFT), α-angle, A5, A10, and A15] were related to MCF by linear or non-linear regression, as appropriate. The Bland-Altman analyses to assess the bias between early ROTEM(®) variables and MCF and receiver operating characteristics (ROC) were also performed. RESULTS: Taking the best and worst correlation coefficients for each assay type, CT (r=0.18-0.49) showed the worst correlation to MCF. In contrast, α-angle (r=0.85-0.88) and CFT (r=0.89-0.92) demonstrated good but non-linear correlation with MCF. The best and linear correlations were found for A5 (r=0.93-0.95), A10 (r=0.96), and A15 (r=0.97-0.98). ROC analyses provided excellent area under the curve (AUC) values for A5, A10, and A15 (AUC=0.962-0.985). CONCLUSIONS: Early values of clot firmness allow for fast and reliable prediction of ROTEM(®) MCF in non-cardiac patients with subnormal, normal, and supranormal MCF values and therefore can be used to guide haemostatic therapy in severe bleeding.

Long-term safety and efficacy of a pasteurized nanofiltrated prothrombin complex concentrate (Beriplex P/N): a pharmacovigilance study.

BACKGROUND: The rapid reversal of the effects of vitamin K antagonists is often required in cases of emergency surgery and life-threatening bleeding, or during bleeding associated with high morbidity and mortality such as intracranial haemorrhage. Increasingly, four-factor prothrombin complex concentrates (PCCs) containing high and well-balanced concentrations of vitamin K-dependent coagulation factors are recommended for emergency oral anticoagulation reversal. Both the safety and efficacy of such products are currently in focus, and their administration is now expanding into the critical care setting for the treatment of life-threatening bleeding and coagulopathy resulting either perioperatively or in cases of acute trauma. METHODS: After 15 yr of clinical use, findings of a pharmacovigilance report (February 1996-March 2012) relating to the four-factor PCC Beriplex P/N (CSL Behring, Marburg, Germany) were analysed and are presented here. Furthermore, a review of the literature with regard to the efficacy and safety of four-factor PCCs was performed. RESULTS: Since receiving marketing authorization (February 21, 1996), ~647 250 standard applications of Beriplex P/N have taken place. During this time, 21 thromboembolic events judged to be possibly related to Beriplex P/N administration have been reported, while no incidences of viral transmission or heparin-induced thrombocytopenia were documented. The low risk of thromboembolic events reported during the observation period (one in ~31 000) is in line with the incidence observed with other four-factor PCCs. CONCLUSIONS: In general, four-factor PCCs have proven to be well tolerated and highly effective in the rapid reversal of vitamin K antagonists.

Early thromboelastometric variables reliably predict maximum clot firmness in patients undergoing cardiac surgery: a step towards earlier decision making.

BACKGROUND: While much effort has been spent on guiding coagulation and transfusion therapy in patients undergoing cardiopulmonary bypass (CPB) surgery, the use of conventional laboratory-based coagulation tests is hampered by long turnaround times and interference with heparin and protamine. To allow faster assessment of maximum clot firmness (MCF) by point-of-care thromboelastometry (ROTEM®, TEM International GmbH, Munich, Germany), we tested whether clotting time (CT), clot formation time (CFT), or early values of clot firmness (CF) predict MCF. METHODS: Results of 437 ROTEM® assays (EXTEM®, INTEM®, FIBTEM®, and HEPTEM®) from 84 patients undergoing CPB surgery were analyzed. Measurements were performed prior to and after heparin administration, as well as after protamine administration and CT, CFT, and CF after 5, 10, and 15 min (A5, A10, and A15) after initial clotting (CT) were related to MCF. STATISTICS: Regression and Bland-Altman analyses and receiver-operating characteristics (ROCs). RESULTS: CFT (r = 0.87-0.95), A5 (r = 0.84-0.98; P < 0.0001), A10 (r = 0.86-0.98; P < 0.0001), and A15 (r = 0.86-0.98; P < 0.0001) demonstrated high correlation coefficients with MCF, whereas CT correlated weakly (r = 0.07-0.41). As expected, correlation coefficients increased with the time allowed to assess a specific variable. ROC analyses demonstrated excellent accuracy for CFT, A5, A10, and A15 [area under the curve (AUC): 0.9476-0.9931] to predict a subnormal MCF, whereas CT demonstrated poor accuracy (AUC: 0.5796-0.6774). CONCLUSION: Taking into account specific bias, early values of CF (A5-A15) reliably predict maximum CF under all conditions and, therefore, allow for marked time savings in the interpretation of ROTEM® measurements. This may guide earlier and more specific treatment of CPB-related coagulation disorders.

Spinal anaesthesia and caesarean section in a patient with hypofibrinogenaemia and factor XIII deficiency.

We report the peri-operative management of a 32-year-old patient suffering from symptomatic hypofibrinogenaemia and factor XIII deficiency scheduled for caesarean section. Starting with an impaired fibrinogen (1.04 g x l(-1)) and factor XIII level (48%), fibrinogen and factor XIII administration was guided by point-of-care rotational thrombelastometry (ROTEM) to achieve normal whole blood coagulation, which allowed uncomplicated spinal anaesthesia and an uneventful surgical procedure. We conclude that rotational thrombelastometry may be suitable to guide administration of coagulation factors in patients with hereditary bleeding disorders and allow otherwise contraindicated neuraxial anaesthesia and surgery to proceed without increased risk of blood loss.

Effects of desmopressin on platelet function under conditions of hypothermia and acidosis: an in vitro study using multiple electrode aggregometry*.

SUMMARY: Hypothermia and acidosis lead to an impairment of coagulation. It has been demonstrated that desmopressin improves platelet function under hypothermia. We tested platelet function ex vivo during hypothermia and acidosis. Blood samples were taken from 12 healthy subjects and assigned as follows: normal pH, pH 7.2, and pH 7.0, each with and without incubation with desmopressin. Platelet aggregation was assessed by multiple electrode aggregometry. Baseline was normal pH and 36 degrees C. The other samples were incubated for 30 min and measured at 32 degrees C. Acidosis significantly impaired aggregation. Desmopressin significantly increased aggregability during hypothermia and acidosis regardless of pH, but did not return it to normal values at low pH. During acidosis and hypothermia, acidosis should be corrected first; desmopressin can then be administered to improve platelet function as a bridge until normothermia can be achieved.

Whole blood coagulation and platelet activation in the athlete: a comparison of marathon, triathlon and long distance cycling.

INTRODUCTION: Serious thrombembolic events occur in otherwise healthy marathon athletes during competition. We tested the hypothesis that during heavy endurance sports coagulation and platelets are activated depending on the type of endurance sport with respect to its running fraction. MATERIALS AND METHODS: 68 healthy athletes participating in marathon (MAR, running 42 km, n = 24), triathlon (TRI, swimming 2.5 km + cycling 90 km + running 21 km, n = 22), and long distance cycling (CYC, 151 km, n = 22) were included in the study. Blood samples were taken before and immediately after completion of competition to perform rotational thrombelastometry. We assessed coagulation time (CT), maximum clot firmness (MCF) after intrinsically activation and fibrin polymerization (FIBTEM). Furthermore, platelet aggregation was tested after activation with ADP and thrombin activating peptide 6 (TRAP) by using multiple platelet function analyzer. RESULTS: Complete data sets were obtained in 58 athletes (MAR: n = 20, TRI: n = 19, CYC: n = 19). CT significantly decreased in all groups (MAR -9.9%, TRI -8.3%, CYC -7.4%) without differences between groups. In parallel, MCF (MAR +7.4%, TRI +6.1%, CYC +8.3%) and fibrin polymerization (MAR +14.7%, TRI +6.1%, CYC +8.3%) were significantly increased in all groups. However, platelets were only activated during MAR and TRI as indicated by increased AUC during TRAP-activation (MAR +15.8%) and increased AUC during ADP-activation in MAR (+50.3%) and TRI (+57.5%). DISCUSSION: While coagulation is activated during physical activity irrespective of type we observed significant platelet activation only during marathon and to a lesser extent during triathlon. We speculate that prolonged running may increase platelet activity, possibly, due to mechanical alteration. Thus, particularly prolonged running may increase the risk of thrombembolic incidents in running athletes.

Impact of platelet count on results obtained from multiple electrode platelet aggregometry (Multiplate).

OBJECTIVES: Use of potent antiplatelet drugs requires evaluation of platelet function. While platelet function in elective cases is usually assessed in a central laboratory environment, there is also an urgent need for rapid perioperative point-of-care assessment. Recently, multiple electrode platelet aggregometry has been developed and assumed to measure platelet function independent from platelet count. We tested the hypothesis that results of multiple electrode platelet aggregometry are affected by platelet count, in particular if platelet count is below normal range. METHODS: Whole blood samples from 20 healthy volunteers were prepared containing platelet concentrations of 50,000, 100,000, 150,000, 200,000, and 250,000 microl(-1) while maintaining hematocrit. Platelet aggregation was induced by collagen, thrombin receptor activating peptide 6 (TRAP-6), adenosine-diphoshate (ADP), and arachidonic acid, respectively, and aggregation was measured by multiple electrode platelet aggregometry (Multiplate). RESULTS: Results of multiple electrode platelet aggregometry significantly decreased in blood samples with platelet count below normal range. Compared to results measured in blood samples with platelet count within normal range, aggregometry results decreased by 18.4 % (p<0.001) and 37.2 % (p<0.001) in blood samples with a platelet count of 100.000 and 50.000 microl(-1), respectively. On the other hand, large interindividual variation has been observed and some blood samples showed normal results even with platelet counts of 50.000 microl(-1). CONCLUSION: The results obtained with Multiplate. Analyzer are influenced by platelet function as well as platelet count thus displaying the overall platelet aggregability within the blood sample rather than platelet function alone.

Venous air embolism induces both platelet dysfunction and thrombocytopenia.

BACKGROUND: In vitro, air bubbles can induce platelet activation and platelet to air bubble binding. We therefore tested in vivo the hypothesis that venous air embolism (VAE) induces (1) platelet dysfunction and (2) thrombocytopenia. METHODS: Adult swine (60.8+/-3.9 kg; n=8) were anaesthetized, mechanically ventilated, and placed in a semi-upright position. Air boli (0.5-80 ml) were injected randomly via an ear vein, and arterial blood was sampled after cumulative air dosages of 0, 80, 160, and 240 ml. Coagulation was assessed by impedance aggregometry, rotational thrombelastometry, whole blood count, plasmatic coagulation variables, and fibrinogen, d-dimer, protein C, and antithrombin plasma concentrations, respectively. RESULTS: VAE induced a 47% decrease in platelet count (303 vs. 160 nl(-1); P<0.001) over the dose range assessed, with haematocrit being unaltered. Furthermore, VAE-impaired platelet aggregation induced by adenosine diphosphate, arachidonic acid, collagen, and the thromboxan analogue U46619 over the dose range assessed independent of thrombocytopenia. (P<0.05 vs. baseline). In contrast, rotational thrombelastometry alone was quite insensitive in detecting VAE-induced coagulation changes, showing only at near lethal air dosages a prolonged clot formation time following activation with tissue factor, contact activator, and during spontaneous coagulation (P<0.05 vs. baseline). CONCLUSIONS: VAE induces both a dose-dependent decrease in platelet count and a marked decrease in platelet aggregation, independent of thrombocytopenia (P<0.05 vs. baseline).

[Therapeutic options for perioperatively acquired platelet dysfunctions]. / Therapieoptionen der perioperativ erworbenen Thrombozytopathie.

Increased intra-operative and postoperative blood loss might be caused by acquired platelet function disorders. In particular because conventional coagulation analyses and platelet count fail to detect impaired platelet function, implementation of bedside-tests for platelet function in the peri-operative period is desirable according to the results of retrospective studies. Following adequate adjustment of basic conditions of haemostasis (e.g. temperature, pH, Ca2+-concentration, haematocrit) a pharmacological approach with desmopressin (1-desamino-8-d-arginine vasopressin; DDAVP) or tranexamic acid potentially represents a low cost alternative to platelet transfusions with minor side effects.

[Coagulation management in multiple trauma]. / Gerinnungsmanagement beim Polytrauma.

More than 25% of polytraumatized patients present in the emergency department with a coagulopathy which results in a 4-fold increase in mortality. The detection of microvascular bleeding is the major clinical indicator. Measurement of fibrinogen, activated partial thromboplastin time and prothrombin time as well as thrombelastometry are required. A prerequisite for the substitution of coagulation factors and platelets is an immediate surgical control of bleeding and correction of hypothermia, acidosis and hypocalcemia. The goals for platelet count, fibrinogen, PT and aPTT are well established. The use of an algorithm for transfusion and coagulation management results in optimized therapy and improved outcome. Substituted coagulation products are only effective if hyperfibrinolysis has been corrected before. The administration of fibrinogen corrects the coagulation factor that is critically reduced earliest, improves global coagulation tests and reduced mortality in some studies. The dose required (3-5 g) can be calculated by a formula. Fresh frozen plasma is given in a 1:1 ratio to red blood cells or at least 20-40 ml/kg body weight. A clear advantage for survival has not yet been shown and some of the risks include insufficient substitution of fibrinogen and transfusion-related acute lung injury. Goals for the administration of platelet concentrates depend on the acuity of bleeding, injury pattern (e.g. head trauma) and clinical signs of microvascular bleeding. Factor VIIa remains an off-label rescue therapy if bleeding persists despite optimization of preconditions and specific coagulation management.

Rotational thrombelastometry for the bedside monitoring of recombinant hirudin.

BACKGROUND: Recombinant hirudin is used as an alternative anticoagulant, particularly in patients with heparin-induced thrombocytopenia type II. However, bedside monitoring for hirudin is not available. The present study aims to evaluate rotational thrombelastometry regarding its suitability to detect the effects of recombinant hirudin on whole blood coagulation. Hirudin was added to whole blood samples from healthy donors (n=5) and thrombelastometry variables resulting from activation of samples with tissue factor, ellagic acid, and ecarin were determined. METHODS: Hirudin (0.1-10 microg/ml) was added to citrated blood. Thereafter, rotational thrombelastometry was performed by initiating coagulation via recalcification and addition of tissue factor, ellagic acid, and ecarin, respectively, using the commercially available assays. RESULTS: In the absence of hirudin, clotting times (CT) induced by ellagic acid, tissue factor, and ecarin, respectively, were 141.7+/-18.0, 54.0+/-7.6, and 64.5+/-4.1 s. Increasing concentrations of hirudin led to dose-dependent prolongation of the clotting time with the three activators. All assays were capable to detect hirudin concentrations in the range of 0.5-5 microg/ml. At a final hirudin concentration of 1 microg/ml, clotting time increased to 268.0+/-25.1, 84.0+/-9.3, and 107.5+/-9.9 s, respectively, with the above-mentioned activators. The other thrombelastographic variables, including clot formation time, angle alpha, and maximum clot firmness, were not altered by hirudin at concentrations up to 5 microg/ml. CONCLUSIONS: Our study demonstrates the suitability of rotational thrombelastometry to detect anticoagulant effects of recombinant hirudin.

[Methods to evaluate aspirin and clopidogrel resistance]. / Methoden zur Messung der Azetylsalizylsäure- bzw. Clopidogrelresistenz.

Based on the concept that the so-called resistance to anti-platelet drugs is meant to describe a phenomenon where the drug does not hit its direct pharmacodynamic target, assays, used to evaluated the effects of anti-platelet drugs, should as closely as possible measure the direct pharmacodynamic effect of a particular drug. Thus, for the detection of aspirin effects, thromboxane concentrations or arachidonic acid-induced responses (light aggregometry, whole-blood aggregometry) should be measured. For the detection of clopidogrel actions, VASP phosphorylation (flow cytometry) or ADP-induced responses (light aggregometry, whole blood aggregometry) should be analysed.

[Coagulation management during liver transplantation]. / Gerinnungsmanagement bei Lebertransplantationen.

In the course of liver transplantation many patients develop coagulation and bleeding disorders. On the other hand, some patients suffer thromboembolic events in the perioperative period with sometimes fatal outcome. For this reason, in 1999 we changed our coagulation management for liver transplantation and abolished the routine prophylaxis with antifibrinolytic drugs. In this context we implemented the ROTEM system (Pentapharm GmbH, Munich) in our perioperative point-of-care coagulation management. From 2000 to 2005, we analysed more than 18,000 ROTEM measurements in the context of 642 liver transplantations. Prophylactic administration of antifibrinolytic drugs was only done in patients with fulminant liver failure or if MCF in ExTEM

Safety and efficacy of recombinant acid alpha-glucosidase (rhGAA) in patients with classical infantile Pompe disease: results of a phase II clinical trial.

Pompe disease is an autosomal recessive muscle-wasting disorder caused by the deficiency of the lysosomal enzyme acid alpha-glucosidase. Due to virtual absence of acid alpha-glucosidase, patients with classical infantile Pompe disease develop progressive cardiomyopathy, skeletal muscle weakness and respiratory insufficiency leading to death in early infancy. We report on the results of a phase II clinical trial including two patients with classical infantile Pompe disease receiving enzyme replacement therapy over a period of 48 weeks by weekly infusions. Recombinant acid alpha-glucosidase was derived from the milk of transgenic rabbits. Safety was evaluated by recording adverse events while clinical efficacy was evaluated by ventilator-free survival, left ventricular mass index, motor development as well as histologic and biochemical analysis of muscle biopsies. This therapy was in general well-tolerated. There was an overall improvement in left ventricular mass, cardiac function, skeletal muscle function and histological appearance of skeletal muscle.

Thromboelastometry for guiding bleeding management of the critically ill patient: a systematic review of the literature.

A systematic review of the published literature clearly demonstrates the usefulness of thromboelastometry (ROTEM®) in detecting coagulation disorders in severe trauma, cardiac and aortic surgery, liver transplantation, and postpartum haemorrhage reliably and within a clinically acceptable turn-around time. In all of the above-mentioned scenarios, the transfusion of any allogeneic blood products could be reduced significantly using ROTEM®-guided bleeding management, thereby minimising or avoiding transfusion-related side effects. Based on the current body of evidence as assessed by the GRADE system, the use of ROTEM® may be recommended in particular for management of severe bleeding after trauma and during cardiac and aortic surgery. However, as laboratory testing contributes only one part of severe bleeding management, the implementation of safe and effective treatment algorithms must be ensured at the same time.