The assessment of platelet function using multiple electrode aggregometry in practical procedures in anaesthesia

BACKGROUND

Platelets are responsible for primary haemostasis. Patients with suspected platelet dysfunction require prompt clinical assessment when qualifying for emergency surgical procedures. The purpose of this article is to present our experience in platelet function assessment using whole-blood multiple electrode aggregometry (MEA) in various clinical conditions.

CASE REPORTS

Retrospective analysis of three patients with thrombocytopathy associated with normal platelet counts was performed using standard laboratory tests complemented by MEA. In two cases, platelet dysfunction was due to antiplatelet drugs, while in one other case it was caused by chronic kidney disease.

CONCLUSIONS

Anaesthesiologists strive to make the perioperative period as safe as possible. Platelet function assessment should be considered in every patient in whom haemostatic disturbances are suspected. MEA provides support for clinical decision-making, especially in patients who undergo haemodialysis or require antiplatelet therapy, and are in need of emergency surgery.

The Double Hazard of Bleeding and Thrombosis in Hemostasis From a Clinical Point of View: A Global Assessment by Rotational Thromboelastometry (ROTEM)

Hemostasis is a complex dynamic process involving bleeding and thrombosis as two end-points. Conventional coagulation tests which are measured in plasma examine only isolated portions of the coagulation cascade, thereby giving no information on important interactions essential to the clinical evaluation of hemostatic function. Thromboelastography (TEG), originally described in 1948 has improved over the decades and become a valuable tool of coagulation testing because of the limitations of standard coagulation tests. TEG is a technique that provides data about the entire coagulation system, from the beginning of clot formation to fibrinolysis, involving both cellular and plasma components of hemostasis. Rotational thromboelastometry (ROTEM) which evolved from TEG technology overcome several limitations of classical TEG while maintaining a good correlation with conventional TEG determination. ROTEM analyses are useful for rapid assessment of global clotting function in various clinical situations including liver transplantation, cardiac surgery, obstetrics, trauma, hemophilia and idiopathic thrombocytopenic purpura. ROTEM has been also reported to be useful in identifying various hypercoagulable conditions including major surgery, malignancy, Behcet’s disease and apheresis. Further developments in ROTEM based transfusion strategies may also reduce transfusion requirements and improve clinical outcomes by optimizing the administration of blood components. This is a literature review of ROTEM including its technique, interpretation and specially clinical applications in different scenarios of bleeding and thrombotic disorders.

Measuring fibrinolysis: from research to routine diagnostic assays

Development and standardization of fibrinolysis methods have progressed more slowly than coagulation testing and routine high-throughput screening tests for fibrinolysis are still lacking. In laboratory research, a variety of approaches are available and are applied to understand the regulation of fibrinolysis and its contribution to the hemostatic balance. Fibrinolysis in normal blood is slow to develop. For practical purposes plasminogen activators can be added to clotting plasma, or euglobulin prepared to reduce endogenous inhibitors, but results are complicated by these manipulations. Observational studies to identify a 'fibrinolysis deficit' have concluded that excess fibrinolysis inhibitors, plasminogen activator inhibitor 1 (PAI-1) or thrombin-activatable fibrinolysis inhibitor (TAFI), zymogen or active enzyme, may be associated with an increased risk of thrombosis. However, results are not always consistent and problems of adequate standardization are evident with these inhibitors and also for measurement of fibrin degradation products (D-dimer). Few methods are available to investigate fibrinolysis under flow, or in whole blood, but viscoelastic methods (VMs) such as ROTEM and TEG do permit the contribution of cells, and importantly platelets, to be explored. VMs are used to diagnose clinical hyperfibrinolysis, which is associated with high mortality. There is a debate on the usefulness of VMs as a point-of-care test method, particularly in trauma. Despite the difficulties of many fibrinolysis methods, research on the fibrinolysis system, taking in wider interactions with hemostasis proteins, is progressing so that in future we may have more complete models and better diagnostic methods and therapeutics.

Noteworthy Literature published in 2017 for Cardiothoracic Anesthesiologists

The year 2017 was a year dominated by large-scale clinical studies reporting the outcome of various interventions in cardiac surgery and heart failure (HF) patients, relevant to all cardiothoracic anesthesiologists. Among them were studies investigating the addition of levosimendan, an alternative inotropic agent, to standard management of patients with HF undergoing cardiac surgery. Also, corticosteroids have been used for various purposes in cardiac patients. Here, a new study reports the effect of high-dose methylprednisolone on recovery and delirium. Furthermore, with increasing evidence that transfusions increase morbidity and mortality, a publication reports the use of rotational thromboelastometry to reduce transfusion requirements. In addition, several randomized controlled multicenter studies report the outcomes of patients undergoing cardiac procedures: surgical versus transcatheter aortic valve replacement in intermediate-risk patients and the use of centrifugal-flow versus axial-flow left-ventricular devices in patients with HF. These studies demonstrate the dynamic and ever-evolving state of perioperative cardiovascular medicine and show us the direction of future developments.

Haptoglobin Reduces Inflammatory Cytokine INF-γ and Facilitates Clot Formation in Acute Severe Burn Rat Model

Haptoglobin exerts renal protective function by scavenging free hemoglobin from the urine and blood stream in patients with hemolytic disorders. Recent studies elucidate the relationships between haptoglobin and inflammation. In addition, coagulopathy is often induced by systemic inflammation characterized by the presence of vascular endothelial damage. We hypothesize that haptoglobin might have an anti-inflammatory effect and affect hypercoagulability using rat burn model. Thirty anesthetized rats of six-weeks of age received over 30% full-thickness scald burn on the dorsal skin surface. All rats were injected with either haptoglobin (Hpt) or normal saline (NS) intraperitoneally. The rats were divided into three groups: 1) control group (NS 20 mL/kg); 2) low concentration of Hpt group, L-Hpt, (Hpt 4 mL (80 U) /kg+NS 16 mL/kg); and 3) high concentration of Hpt group, H-Hpt, (Hpt 20 mL (400 U) /kg). While under anesthesia, all rats were euthanized by exsanguination at 6 hours (N=5) and 24 hours (N=5). Inflammatory and anti-inflammatory cytokines were measured and whole-blood viscoelastic tests were performed by thromboelastometry (ROTEM). Haptoglobin significantly reduced free hemoglobin 24 hours after the injury. Improvement of hematuria was confirmed in the H-Hpt group. There were no differences in thrombin-antithrombin complex and plasmin-α2 plasmin inhibitor complex. The haptoglobin tended to decrease interferon-gamma (IFN-γ) in H-Hpt group. ROTEM findings of the L-Hpt group showed significantly higher clot firmness and shorter time to maximum clot formation velocity than the control group. Haptoglobin reduced INF-γ, and accelerated speed of clot formation in acute phase of severe burn.

Evaluation of Thromboelastometry in Sepsis in Correlation With Bleeding During Invasive Procedures

Prolongation of prothrombin time (PT) is often encountered in patients with sepsis. On the other hand, thromboelastometry as a global coagulation test might yield normal results. The aim of our study was to evaluate whether prolonged PT in the presence of normal thromboelastometry parameters is associated with severe bleeding in patients with sepsis undergoing invasive procedures. In patients with sepsis undergoing low-risk bleeding invasive procedures (central venous catheter placement, dialysis catheter insertion, drain insertion, and so on) or high-risk bleeding invasive procedures (surgical tracheostomy, surgical laparotomy, thoracotomy, and so on), coagulation was assessed by thromboelastometry using EXTEM test (test for evaluation of the extrinsic pathway of coagulation, contains activator of extrinsic pathway) and with PT. For period of years 2013 to 2016, we assessed occurrence of severe bleeding during those procedures and 24 hours later in patients with prolonged PT and normal thromboelastometry results. This retrospective study was performed at Department of Anaesthesiology and Intensive Care Medicine of Motol University Hospital in Prague. Data from 76 patients with sepsis were analyzed. Median value of international normalized ratio (INR) was 1.59 (min—1.3 and max—2.56), and median value of prothrombin ratio (PR) was 1.5 (min—1.23 and max—2.55) with normal thromboelastometry finding. Despite prolonged INR/PR, no severe bleeding was observed during invasive procedures. Our data show that sepsis may be accompanied by normal thromboelastometry results, despite prolonged values of PT, and invasive procedures were performed without severe bleeding. This approach to coagulation assessment in sepsis may reduce administration of fresh frozen plasma to the patients. The study was registered at Clinical Trials.gov with assigned number NCT02971111.

Research protocol for platelets in out-of-hospital cardiac arrest: an observational, case-controlled, feasibility study to assess coagulation and platelet function abnormalities with ROTEM following out-of-hospital cardiac arrest (PoHCAR)

INTRODUCTION

Out-of-hospital cardiac arrest (OHCA) has an annual incidence of approximately 60 000 in the UK. Less than 10% of those who receive resuscitation survive to hospital discharge. For OHCA of a presumed cardiac cause, the optimal antiplatelet therapy is currently unknown. Previous studies indicate that a procoagulopathic state exists postcardiac arrest which may contribute to the formation of thrombi and contribute to poor outcomes. However, the administration of antiplatelet therapies needs to be balanced against the increased risk of bleeding that these individuals face.

METHODS AND ANALYSIS

This observational feasibility study will recruit 30 individuals who achieve return of spontaneous circulation post-OHCA, are admitted to a single tertiary centre over a 6-month period and meet Utstein cohort criteria (witnessed cardiac arrest, VF or pulseless VT and cardiac cause of arrest likely). Rotational thromboelastometry and platelet function assessment will be performed on hospital arrival, postemergency percutaneous coronary intervention (PCI) and 12 hours, 24 hours and 48 hours post-PCI. As a comparator, 30 individuals presenting to our institution with ST-segment elevation myocardial infarction and undergoing primary PCI will have the same blood sampling performed. Plasma samples will be retained and batch tested on completion of the study for levels of protein C, protein S, thrombin-antithrombin complex, thrombin, antithrombin, plasminogen activator inhibitor-1, plasmin-antiplasmin complex, d-dimer, platelet factor-4, P selectin, E selectin and prothrombin fragments 1 and 2. 30-day follow-up for complications will be undertaken.

ETHICS AND DISSEMINATION

This study has been approved by the Wales REC 7Research Ethics Committee. The results will be submitted to peer-reviewed medical journals and suitable national and international meetings. Results will be locally disseminated via our patient and public interest group.

TRIAL REGISTRATION NUMBER

Pre-results; ISRCTN34122839.

Preoperative thromboelastometry for the prediction of increased chest tube output in cardiac surgery: A retrospective study

Bleeding following cardiac surgery is a serious event with potentially life-threatening consequences. Preoperative recognition of coagulation abnormalities and detection of cardiopulmonary bypass (CPB) related coagulopathy could aid in the start of preventive treatment strategies that minimize perioperative blood loss. Most algorithms that analyze thromboelastometry coagulation tests in elective cardiac surgery do not include test results performed before surgery. We evaluated preoperative rotational thromboelastometry test results for their ability to predict blood loss during and after cardiac surgery.A total of 114 adult patients undergoing cardiac surgery with CPB were included in this retrospective analysis. Each patient had thromboelastometry tests done twice: preoperatively, before the induction of anesthesia and postoperatively, 10 minutes after heparin reversal with protamine after decannulation.Patients were placed into 1 of 2 groups depending on whether preoperative thromboelastometry parameters deviated from reference ranges: Group 1 [N = 29; extrinsically activated test (EXTEM) or INTEM results out of normal range] or Group 2 (N = 85; EXTEM and INTEM results within the normal range). We observed that the total amount of chest tube output was significantly greater in Group 1 than in Group 2 (700 mL vs 570 mL, P = .03). At the same time, the preoperative values of standard coagulation tests such as platelet count, aPTT, and INR did not indicate any abnormalities of coagulation.Preoperative coagulation abnormalities diagnosed with thromboelastometry can predict increased chest tube output in the early postoperative period in elective adult cardiac surgery. Monitoring of the coagulation system with thromboelastometry allows rapid diagnosis of coagulation abnormalities even before the start of the surgery. These abnormalities could not always be detected with routine coagulation tests.

Evaluation of thromboelastometry parameters as predictive markers for sinusoidal obstruction syndrome in patients undergoing allogeneic stem cell transplantation for acute leukaemia

Hepatic sinusoidal obstruction syndrome (previously named veno-occlusive disease, SOS/VOD) is a serious complication of allogeneic stem cell transplantation (HSCT). Early identification of patients at risk of SOS/VOD may possibly improve the outcome and reduce mortality. Rotation thromboelastometry (ROTEM) is global assay allowing for the precise assessment of both bleeding and thrombotic conditions, however, its usefulness in patients undergoing HSCT for acute leukaemia has not been studied.

We evaluated the thromboelastometry parameters in patients undergoing allogeneic HSCT for acute leukaemia to identify candidate biomarkers of SOS/VOD occurrence.

ROTEM assays (INTEM, EXTEM, FIBTEM, APTEM) were performed on day -10, on the day of stem cell infusion (day 0) and on days +12 and +28 post-HSCT. The diagnosis of SOS/VOD was based on the Baltimore criteria. Seven patients (26%) developed SOS/VOD. On day +12, the patients with SOS/VOD had statistically significant longer INTEM-CT (clotting time, 199 ± 33.41vs166 ± 23.65s, p = 0.0033), EXTEM-CT (69.5 ± 6.39vs.52 ± 3.42s, p = 0.0139) and FIBTEM-CT (69.5 ± 22.75vs. 50.8 ± 14.31s, p = 0.0124) compared to SOS/VOD (-). ROC curve on day +12 indicated a cut-off value of 179s in INTEM-CT (AUC = 0.91), 69s in EXTEM-CT (AUC = 0.90) and 102s in FIBTEM-CT (AUC = 0.82) for the prediction of SOS/VOD.

This is the first study evaluating the usefulness of ROTEM assays in the early detection of haemostasis abnormalities predictive of SOS/VOD development in patients undergoing HSCT for acute leukemia. Patients with SOS/VOD had a significant delay in the initiation of thrombin formation in the analysed ROTEM assays. The utility of ROTEM assays in the optimal management of patients undergoing HSCT should be clarified in further prospective studies.

Thromboelastometry: Relation to the severity of liver cirrhosis in patients considered for liver transplantation

The severity of liver disease is assessed by scoring systems, which include the conventional coagulation test prothrombin time-the international normalized ratio (PT-INR). However, PT-INR is not predictive of bleeding in liver disease and thromboelastometry (ROTEM) has been suggested to give a better overview of the coagulation system in these patients. It has now been suggested that coagulation as reflected by tromboelastomety may also be used for prognostic purposes. The objective of our study was to investigate whether thrombelastometry may discriminate the degree of liver insufficiency according to the scoring systems Child Pugh and Model for End-stage Liver Disease (MELD).Forty patients with chronic liver disease of different etiologies and stages were included in this observational cross-sectional study. The severity of liver disease was evaluated using the Child-Pugh score and the MELD score, and blood samples for biochemistry, conventional coagulation tests, and ROTEM were collected at the time of the final assessment for liver transplantation. Statistical comparisons for the studied parameters with scores of severity were made using Spearman correlation test and receiver-operating characteristic (ROC) curves.Spearman correlation coefficients indicated that the thromboelastometric parameters did not correlate with Child-Pugh or MELD scores. The ROC curves of the thromboelastometric parameters could not differentiate advanced stages from early stages of liver cirrhosis.Standard ROTEM cannot discriminate the stage of chronic liver disease in patients with severe chronic liver disease.

Can prepartum thromboelastometry-derived parameters and fibrinogen levels really predict postpartum hemorrhage?

BACKGROUND

Decreased postpartum rotational thromboelastometric parameters of coagulation (ROTEM®) and fibrinogen levels have been associated with postpartum hemorrhage (PPH). However, the predictive power of prepartum ROTEM® parameters and fibrinogen levels (Fbgpre) for PPH remains unknown.

METHODS

This prospective observational pilot study included 217 healthy pregnant women. Maximum clot firmness (FIBTEM-MCF), fibrinogen levels and standard coagulation parameters were measured upon admission to the delivery room for labor and within 1 h after vaginal delivery. Blood loss was measured with a calibrated collecting drape during the third stage of labor. PPH was defined as blood loss ≥500 mL. Predictors for bleeding were identified via receiver operating characteristic analyses and bivariate and multivariate regression analyses.

RESULTS

Women with and without PPH did not differ in median FIBTEM-MCF [23 mm (25th percentile 20 mm, 75th percentile 26 mm) vs. 23 mm (19 mm, 26 mm), respectively; P=0.710] or mean Fbgpre (4.57±0.77 g/L vs. 4.45±0.86 g/L, respectively; P=0.431). Blood loss and prepartum coagulation parameters were not correlated (FIBTEM-MCF, rs=-0.055, P=0.431; Fbgpre, rs=-0.017, P=0.810). The areas under the curves (predictive power for PPH) for FIBTEM-MCF and Fbgpre and were 0.52 (0.41-0.64, P=0.699) and 0.53 [95% confidence interval (95% CI) 0.40-0.65, P=0.644], respectively. Neither FIBTEM-MCF nor Fbgpre was associated with PPH. However, primiparity [odds ratio (OR) 4.27, 95% CI 1.32-13.80, P=0.015) and urgent cesarean section (2.77, 1.00-7.67, P=0.050) were independent predictors of PPH.

CONCLUSIONS

ROTEM® parameters, Fbgpre and postpartum blood loss were not associated, nor did these factors predict PPH. Sufficiently powered prospective studies are needed to confirm these results.

Increased Clot Formation in the Absence of Increased Thrombin Generation in Patients with Peripheral Arterial Disease: A Case-Control Study

Background

In peripheral arterial disease (PAD), activation of the hemostatic system may contribute to atherosclerosis progression and atherothrombotic events.

Objective

This case–control study assesses the overall coagulation status in PAD patients by evaluating coagulation markers in combination with thrombin generation potential, whole blood (WB) clot formation, and fibrinolysis.

Methods

In blood from 40 PAD patients (n = 20 with cardiovascular event within 1 year after initial diagnosis, n = 20 without) and 40 apparently healthy controls, thrombin generation was determined in WB and platelet-poor plasma. Whole blood rotational thromboelastometry (ROTEM) measurements were triggered with tissue factor with/without tissue plasminogen activator.

Results

We observed increased levels of erythrocyte sedimentation rate, leukocytes, eosinophil granulocytes, vWF antigen, fibrinogen, and D-dimer in PAD patients (p < 0.05). Markers of thrombin generation potential showed no difference between patients and healthy controls. In PAD patients with event compared to patients without, WB-thrombin generation showed a lower thrombin potential when triggered with 0 and 2.5 pM tissue factor. The ROTEM clotting assay showed significantly faster clot formation and increased clot firmness in PAD patients compared to controls. No significant differences were found for parameters of clot degradation.

Conclusion

There are no significant differences between the thrombin generation profiles of PAD patients and healthy controls. Between PAD patients with and without cardiovascular event, the WB thrombin generation appears to differ. Mechanistically, PAD patients show an increased ability to form a stable clot in WB in comparison to healthy controls. This is most likely due to the increased fibrinogen levels related to the inflammation in atherosclerosis, confirming the importance of the inflammation-coagulation axis.

Using antifibrinolytics in the peripartum period - concern for a hypercoagulable effect?

INTRODUCTION

Although antifibrinolytic agents are used to prevent and treat hemorrhage, there are concerns about a potential increased risk for peripartum venous thromboembolism. We sought to determine the impact of tranexamic acid and ɛ-aminocaproic acid on in vitro clotting properties in pregnancy.

METHODS

Blood samples were obtained from healthy pregnant, obese, and preeclamptic pregnant women (n = 10 in each group) prior to delivery as well as from healthy non-pregnant controls (n = 10). Maximum clot firmness (MCF) and clotting time (CT) were measured using rotation thromboelastometry in the presence of tranexamic acid (3, 30, or 300 μg/mL) or ɛ-aminocaproic acid (30, 300, or 3000 μg/mL). ANOVA and regression analyses were performed.

RESULTS

Mean whole blood MCF was significantly higher in healthy pregnant vs. non-pregnant women (66.5 vs. 57.5 mm, p < 0.001). Among healthy pregnant women, there was no significant difference between mean MCF (whole blood alone, and with increasing tranexamic acid doses = 66.5, 66.1, 66.4, 66.3 mm, respectively; p = 0.25) or mean CT (409, 412, 420, 424 sec; p = 0.30) after addition of tranexamic acid. Similar results were found using ɛ-aminocaproic acid. Preeclamptic women had a higher mean MCF after the addition of ɛ-aminocaproic acid and tranexamic acid (p = 0.05 and p = 0.04, respectively) compared to whole blood alone.

CONCLUSIONS

Pregnancy is a hypercoagulable state, as reflected by an increased MCF compared to non-pregnant women. Addition of antifibrinolytic therapy in vitro does not appear to increase MCF or CT for non-pregnant, pregnant, and obese women. Whether antifibrinolytics are safe in preeclampsia may require further study.

Comparison of the effects of a balanced crystalloid-based and a saline-based tetrastarch solution on canine whole blood coagulation and platelet function

OBJECTIVE

To evaluate the effects of a 6% hydroxyethyl starch (130/0.42) solution in either a buffered, electrolyte-balanced (HES-BAL), or a saline (HES-SAL) carrier solution on canine platelet function and whole blood coagulation.

DESIGN

Prospective, randomized study.

SETTING

University teaching hospital.

ANIMALS

Thirty-seven client-owned dogs undergoing general anesthesia for arthroscopy or imaging studies.

INTERVENTIONS

Dogs received a 15 mL/kg intravenous bolus of HES-SAL (n = 13), HES-BAL (n = 14), or a modified Ringer's solution (n = 10) over 30-40 minutes. Coagulation was analyzed using a Platelet Function Analyzer-100 (closure time [Ct_PFA ]), and whole blood thromboelastometry (ROTEM) with extrinsically (ex-tem and fib-tem) and intrinsically (in-tem) activated assays, which assessed clotting time (CT), clot formation time (CFT), maximal clot firmness (MCF), and lysis index (LI). Coagulation samples were assayed prior to fluid administration (T0), and 5 minutes (T1), and 3 hours (T2) following fluid bolus administration, respectively.

RESULTS

Both HES solutions resulted in impaired platelet function as indicated by a significant prolongation of Ct_PFA at T1 as compared to T0, but which resolved by T2. An IV bolus of Ringer's solution did not alter platelet function. In both HES groups, whole blood coagulation was significantly impaired at T1 as indicated by a significant increase in in-tem CFT, and a significant decrease in ex-tem, in-tem, and fib-tem MCF compared to T0. Furthermore, a significant increase in ex-tem CFT at T1 compared to T0 was found in the HES-SAL group. With the exception of in-tem MCF after HES-BAL, these effects were not present at T2. No significant differences were found in Ct_PFA or any ROTEM variable at any time point between HES-SAL and HES-BAL.

CONCLUSION

Administration of a single bolus of 15 mL/kg 6% HES 130/0.42 results in significant but short-lived impairment of canine platelet function and whole blood coagulation, regardless of carrier solution.

The thromboelastometric discrepancy between septic and trauma induced disseminated intravascular coagulation diagnosed by the scoring system from the Japanese association for acute medicine

The aim of this study is to evaluate the hematological differences between septic and traumatic disseminated intravascular coagulation (DIC) using the rotational thromboelastometry (ROTEM).This retrospective study includes all sepsis or severe trauma patients transported to our emergency department who underwent ROTEM from 2013 to 2014. All patients were divided into 2 groups based on the presence of DIC diagnosed by the Japanese Association for Acute Medicine (JAAM) DIC score. We statistically analyzed the demographics, clinical characteristics, laboratory data, ROTEM findings (EXTEM and FIBTEM), and outcome.Fifty-seven patients (30 sepsis and 27 severe trauma) were included in primary analysis. Sepsis cases were significantly older and had higher systemic inflammatory response syndrome (SIRS) scores, whereas there were no significant differences in other parameters including Acute Physiology and Chronic Health Evaluation (APACHE) II score, sequential organ failure assessment (SOFA) score. Twenty-six patients (14 sepsis and 12 severe trauma) were diagnosed with DIC. The Septic DIC (S-DIC) group was significantly older and had higher DIC scores than the traumatic DIC (T-DIC) group. Hematologic examination revealed significantly higher CRP, fibrinogen, lower FDP, DD, and higher FDP/DD ratio were found in the S-DIC group in comparison with the T-DIC group. ROTEM findings showed that the A10, A20, and MCF in the FIBTEM test were significantly higher in the S-DIC group. However, no statistical differences were confirmed in the LI30, LI45, and ML in EXTEM test.The plasma fibrinogen level and fibrinogen based clot firmness in whole-blood test revealed statistical significance between septic and traumatic DIC patients.

Impact of incorrect filling of citrate blood sampling tubes on thromboelastometry

BACKGROUND

ROTEM(®) test results can be affected by the citrate to blood ratio in the tested sample. Overfilling or underfilling specimen tubes can change this ratio.

OBJECTIVES

The aim of this study was to determine the impact of under- and overfilling citrate test tubes on ROTEM(®) EXTEM measurements.

RESULTS

Overall repeated measures ANOVA demonstrated significant differences of CT (p = 0.004), CFT (p = 0.005), A5 (p = 0.001), A10 (p <0.001), and MCF (p < 0.001). Pairwise comparison revealed that underfilling significantly altered the results of those parameters reflecting functional clot firmness (A5, A10, and MCF), while overfilling led to a prolongation of the CT results only. No differences were observed for alpha angle and maximum lysis.

CONCLUSION

Both underfilling and overfilling specimen tubes have significant influence on the results of the ROTEM(®) EXTEM test, although the small observed bias is likely of limited clinical relevance. However, it seems prudent to limit the maximum allowed difference in filling to less than ± 10%. All ROTEM(®) operators should be aware of this pre-analytical variable.

Normalization methods in time series of platelet function assays: A SQUIRE compliant study

Platelet function can be quantitatively assessed by specific assays such as light-transmission aggregometry, multiple-electrode aggregometry measuring the response to adenosine diphosphate (ADP), arachidonic acid, collagen, and thrombin-receptor activating peptide and viscoelastic tests such as rotational thromboelastometry (ROTEM).The task of extracting meaningful statistical and clinical information from high-dimensional data spaces in temporal multivariate clinical data represented in multivariate time series is complex. Building insightful visualizations for multivariate time series demands adequate usage of normalization techniques.In this article, various methods for data normalization (z-transformation, range transformation, proportion transformation, and interquartile range) are presented and visualized discussing the most suited approach for platelet function data series.Normalization was calculated per assay (test) for all time points and per time point for all tests.Interquartile range, range transformation, and z-transformation demonstrated the correlation as calculated by the Spearman correlation test, when normalized per assay (test) for all time points. When normalizing per time point for all tests, no correlation could be abstracted from the charts as was the case when using all data as 1 dataset for normalization.

Is viscoelastic coagulation monitoring with ROTEM or TEG validated?

Recent years have seen increasing worldwide interest in the use of viscoelastic coagulation monitoring tests, performed using devices such as ROTEM and TEG. The use of such tests to guide haemostatic therapy may help reduce transfusion of allogeneic blood products in bleeding patients and is supported in European guidelines for managing trauma and severe perioperative bleeding. In addition, viscoelastic tests form the basis of numerous published treatment algorithms. However, some publications have stated that viscoelastic tests are not validated. A specific definition of the term validation is lacking and regulatory requirements of the US Food and Drug Administration (FDA) and European Medicines Agency (EMA) have been fulfilled by ROTEM and TEG assays. Viscoelastic tests have been used in pivotal clinical trials, and they are approved for use in most of the world's countries. Provided that locally approved indications are adhered to, the regulatory framework for clinicians to use viscoelastic tests in routine clinical practice is in place.

Thromboelastographic profiles of the premature infants with and without intracranial hemorrhage at birth: a pilot study

OBJECTIVE

To delineate thromboelastographic profiles of the premature infants with and without intracranial hemorrhage during the first 21 days of life.

METHODS

In this study, 49 premature infants (24 female; 25 male) were consecutively admitted at our neonatal intensive care unit during a 6 months period were subject to thromboelastography and standard coagulation assessments at birth and weekly up to 21 days. Sixteen out of 49 infants developed intracranial hemorrhage at birth.

RESULTS

The test results of 127/196 were considered eligible for analysis. Overall significant changes of the main thromboelastographic parameters were observed shortly after birth. Newborns with intracranial hemorrhage showed increased thromboelastogram-defined thrombin generation (shorter R and time to maximum amplitude times) from birth onward, suggesting a hypercoagulable state. No significant differences concerning thromboelastographic and coagulation assays parameters were found at birth between infants with and without intracranial hemorrhage, except for higher plasma D-Dimer concentration (p = 0.002) in the former infants. Finally, a positive correlation between clot lysis time and gestational age (Spearman's rho = 0.502, p = 0.002) was observed.

CONCLUSIONS

Thromboelastographic profiles of the premature infants suggest an effective hemostatic function during the first post-natal weeks. Further study is needed to determine whether thromboelastography may be more useful than coagulation assays to reflect the bleeding risk of the premature infants.

Comparative biochemical studies of fresh frozen plasma and pooled solvent/detergent-treated plasma (octaplasLG® ) with focus on protein S and its impact in different thrombin generation assay set-ups

BACKGROUND AND OBJECTIVES

The solvent/detergent treatment enables effective and robust inactivation of all lipid-enveloped viruses, but also inactivates partly sensitive plasma proteins such as protein S. The aim of this study was to investigate the thrombin generation capacity of octaplasLG^® , in particular focusing on the function of protein S in thrombin generation assay and the impact of assay settings.

MATERIALS AND METHODS

Sixteen octaplasLG^® batches and 32 units of single donor fresh frozen plasma (FFP) were investigated. For protein S, both functional activity and free antigen levels were measured. Thrombin generation assay was performed using two fluorogenic tests with different triggers. Finally, rotational thromboelastometry was performed.

RESULTS

Mean protein S levels were lower in octaplasLG^® , but a wider range of values was found for FFP. Clotting parameters and thrombin generation capacities overlapped between the two plasma groups as demonstrated using both thrombin generation assays and different triggers. Spiking studies with protein S-depleted plasma, human purified protein S or antibodies against protein S confirmed a correlation between protein S and thrombin generation capacity under specific assay conditions, especially in an assay with low tissue factor concentration.

CONCLUSION

Correlation between protein S and thrombin generation capacity was demonstrated in the TGA. Due to higher variability in protein S content in the FFP group, overlapping haemostatic potentials of the two plasma groups were found.

Nonclinical analysis of the safety, pharmacodynamics, and pharmacokinetics of plasma-derived human FXIII concentrate in animals

Factor XIII (FXIII) is a coagulation protein which plays a major role in hemostasis by covalently cross‐linking fibrin molecules, thereby stabilizing the blood clot and increasing resistance to fibrinolysis. FXIII deficiency, either congenital or acquired, is associated with spontaneous bleeding, increased bleeding time, and poor wound healing. Purified plasma‐derived human FXIII concentrate (pd hFXIII) has been available since 1993 for therapeutic use in congenital FXIII deficiency. This set of nonclinical investigations aimed to evaluate the pharmacodynamic effects and assess the safety profile of pd hFXIII. The efficacy and safety of pd hFXIII were evaluated by pharmacodynamic, pharmacokinetic, and toxicity studies in mice and rats, safety pharmacology studies in dogs, neoantigenicity study, local tolerance, and thrombogenicity tests in rabbits. Administration of pd hFXIII resulted in the correction of deficits in clot formation kinetics and strength as measured by thromboelastometry, and was not associated with thrombus formation up to 350 IU/kg in FXIII knockout mice. There was no production of neoantigens resulting from the viral elimination manufacturing steps detected, and no adverse reactions were observed in toxicity studies with single doses up to 3550 IU/kg in mice and 1420 IU/kg in rats; nor from repeat doses of 350 IU/kg in rats. In addition, local tolerance tests revealed a good tolerability profile in rabbits. Overall, this data showed that pd hFXIII was well tolerated and pharmacodynamically active in preclinical animal models, supporting pd hFXIII as a therapy for FXIII deficiency.

Economic aspects of intraoperative coagulation management targeting higher fibrinogen concentrations during major craniosynostosis surgery

BACKGROUND

Results of a previously published study demonstrated a significant decrease in transfusion requirements and calculated blood loss for pediatric major craniosynostosis surgery, if a ROTEM(®) FIBTEM trigger of <13 mm (early substitution group) was applied as compared to a trigger of <8 mm (conventional group). The aim of this study was a posthoc analysis of the costs for this coagulation management.

METHODS

The total volume as well as the number of units or bags for all transfused blood products and coagulation factors were recorded for each case. The number of laboratory and point-of-care coagulation tests was also analyzed. Total blood product costs were calculated according to the local prices per unit.

RESULTS

The total cost for all transfused/administered blood products/coagulation factors per patient was a median of 1023EUR (IQR 850EUR-1058EUR) in the early substitution group as compared to a median of 910EUR (IQR 719EUR-1351EUR) in the conventional group (P = 0.81). No difference in the number of coagulation tests performed was observed.

CONCLUSION

In this study, the use of a higher fibrinogen trigger was not linked to a significant increase in total costs for transfused blood products and coagulation factors, and may offer an economically equivalent approach to coagulation management.

Thromboelastography: A Practice Summary for Nurse Practitioners Treating Hemorrhage

Nurse practitioners may manage patients with coagulopathic bleeding which can lead to life-threatening hemorrhage. Routine plasma-based tests such as prothrombin time and activated partial thromboplastin time are inadequate in diagnosing hemorrhagic coagulopathy. Indiscriminate administration of fresh frozen plasma, platelets or cryoprecipitate for coagulopathic states can be extremely dangerous. The qualitative analysis that thromboelastography provides can facilitate the administration of the right blood product, at the right time, thereby permitting the application of goal-directed therapy for coagulopathic intervention application and patient survival.

Comparison of the in vitro effects of saline, hypertonic hydroxyethyl starch, hypertonic saline, and two forms of hydroxyethyl starch on whole blood coagulation and platelet function in dogs

OBJECTIVE

To compare the in vitro effects of hypertonic solutions and colloids to saline on coagulation in dogs.

DESIGN

In vitro experimental study.

SETTING

Veterinary teaching hospital.

ANIMALS

Twenty-one adult dogs.

INTERVENTIONS

Blood samples were diluted with saline, 7.2% hypertonic saline solution with 6% hydroxyethylstarch with an average molecular weight of 200 kDa and a molar substitution of 0.4 (HH), 7.2% hypertonic saline (HTS), hydroxyethyl starch (HES) 130/0.4 or hydroxyethyl starch 600/0.75 at ratios of 1:22 and 1:9, and with saline and HES at a ratio of 1:3.

MEASUREMENTS AND MAIN RESULTS

Whole blood coagulation was analyzed using rotational thromboelastometry (extrinsic thromboelastometry-cloting time (ExTEM-CT), maximal clot firmness (MCF) and clot formation time (CFT) and fibrinogen function TEM-CT (FibTEM-CT) and MCF) and platelet function was analyzed using a platelet function analyzer (closure time, CTPFA ). All parameters measured were impaired by saline dilution. The CTPFA was prolonged by 7.2% hypertonic saline solution with 6% hydroxyethylstarch with an average molecular weight of 200 kDa and a molar substitution of 0.4 (HH) and HTS but not by HES solutions. At clinical dilutions equivalent to those generally administered for shock (saline 1:3, HES 1:9, and hypertonic solutions 1:22), CTPFA was more prolonged by HH and HTS than other solutions but more by saline than HES. No difference was found between the HES solutions or the hypertonic solutions. ExTEM-CFT and MCF were impaired by HH and HTS but only mildly by HES solutions. At clinically relevant dilutions, no difference was found in ExTEM-CFT between HTS and saline or in ExTEM-MCF between HH and saline. No consistent difference was found between the 2 HES solutions but HH impaired ExTEM-CFT and MCF more than HTS. At high dilutions, FibTEM-CT and -MCF and ExTEM-CT were impaired by HES.

CONCLUSIONS

Hypertonic solutions affect platelet function and whole blood coagulation to a greater extent than saline and HES. At clinically relevant dilutions, only CTPFA was markedly more affected by hypertonic solutions than by saline. At high dilutions, HES significantly affects coagulation but to no greater extent than saline at clinically relevant dilutions.

Warfarin therapy and perioperative transfusion requirement with bleeding amount in patients undergoing cardiac surgery with cardiopulmonary bypass: a retrospective study

OBJECTIVES

The study was designed to evaluate the effect of warfarin on perioperative transfusion, bleeding and coagulation status in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

BACKGROUND

There were controversy about the effect of warfarin on perioperative transfusion and bleeding.

METHODS/MATERIALS

Medical records from 107 consecutive patients with atrial fibrillation (AF) on warfarin therapy undergoing cardiac surgery with cardiopulmonary bypass (CPB) from 2008 to 2013 at a single university teaching hospital were retrospectively reviewed to compare the patients on to those not on warfarin therapy in terms of perioperative transfusion requirement, postoperative 24-h bleeding amount, and coagulation status assessment using prothrombin time (PT), international normalised ratio (INR) and rotational thromboelastometry (ROTEM®).

RESULTS

Although PT/INR was significantly prolonged both before and after surgery in patients on warfarin therapy, ROTEM® data, perioperative transfusion requirement and postoperative 24-h bleeding amount (785 ± 331 vs 676 ± 303 mL, P = 0·089, respectively) were not significantly different between the patients on and those not on warfarin therapy.

CONCLUSION

In patients on warfarin therapy undergoing cardiac surgery with CPB, warfarin therapy did not significantly increase perioperative transfusion requirement and bleeding.

Influence of Two Colloidal Extracorporeal Primes on Coagulation of Cardiac Surgical Patients: A Prospectively Randomized Open-Label Pilot Trial

The search for the ideal priming fluid continues as more evidence is discovered about side effects of volume expanders. With the availability of modern, balanced hydroxyethyl starch (HES) solutions with less side effects than former HES solutions, we considered to replace our gelatin- (modified gelatin) based extracorporeal circuit prime for a HES (130/.42) prime. Therefore, we studied the influence of two colloidal priming fluids on postoperative coagulation in patients undergoing cardiac surgery. The primary endpoint was to compare clot formation time between the HES group and the gelatin group with rotational thromboelastometry (ROTEM). Additionally we compared colloid osmotic pressure and fluid balance of both groups. Forty patients, undergoing elective first time coronary artery bypass grafting or single-valve surgery, were included in this prospectively randomized open-label pilot study. Laboratory data and ROTEM data were collected and analyzed for differences between the two groups. ROTEM data show significantly more prolongation in Extem clot formation time and significant more decrease in Extem alpha in the HES group. Fibtem maximum clot firmness was significantly smaller in the HES group; this was consistent with fibrinogen concentration measurement, which decreased more in the HES group than in the gelatin group and recovered more over time in the gelatin group. We found no significant difference in colloid. osmotic pressure between the groups. In this trial, HES (130/.42) impairs coagulation significantly more compared with gelatin. These differences in influence on coagulation did not lead to a difference in blood loss or fluid balance, so clinical relevance could not be proven.

Cirrhosis patients have a coagulopathy that is associated with decreased clot formation capacity

BACKGROUND

The coagulopathy in cirrhosis is associated with thrombosis and bleeding.

OBJECTIVES

To gain better insights into the coagulopathy in patients with cirrhosis, we evaluated plasma thrombin generation and whole blood clot formation in a cross-sectional study.

METHODS

Blood was collected from 73 patients with all-cause cirrhosis (Child-Pugh-A n = 52, B n = 15, C n = 6) and 20 healthy controls. Activity of the coagulation pathways was measured with assays for factor (F) VIIa and FIXa-antithrombin and FXa-antithrombin complexes, respectively. Thrombin generation by calibrated automated thrombography was determined in platelet-poor plasma using a 1 or 5 pm tissue factor trigger with/without thrombomodulin. ROTEM measurements were performed in whole blood triggered with 35 pm tissue factor without/with 175 ng mL(-1) tissue plasminogen activator (the latter refered to as 'tPA-ROTEM').

RESULTS

We observed an increased generation of FVIIa and a moderately elevated amount of FIXa (in complex with antithrombin) without apparent increase in FX activation in patients with cirrhosis. In accordance with this prothrombotic state, markers of thrombin generation potential were also increased upon increasing severity of cirrhosis. In the whole blood clotting assay we observed delayed clot formation and decreased clot strength associated with increased severity of cirrhosis. No significant differences were found for tPA-ROTEM parameters of clot degradation.

CONCLUSION

These results indicate that cirrhosis patients have an overall procoagulant plasma milieu but a decreased whole blood clot formation capacity with an apparently unaltered resistance to clot lysis.

Improvements in patient blood management for pediatric craniosynostosis surgery using a ROTEM(®) -assisted strategy - feasibility and costs

BACKGROUND

Moderate to severe intraoperative bleeding and the presence of acquired coagulopathy remain serious problems in the management of major pediatric craniosynostosis surgery. After implementation of a ROTEM(®) -assisted patient blood management (PBM) strategy, using primarily purified coagulation factor concentrates, feasibility and costs of this new regimen were analyzed.

METHODS

Retrospective analysis of all consecutive children who underwent primary elective major craniofacial surgery for craniosynostosis repair was carried out at the Children's University Hospital, Zurich, between 2007 and 2013. Laboratory workup and transfusion requirements were compared.

RESULTS

A total of 47 children (36 in the historic group and 11 after implementation of PBM) were analyzed. Although all patients in this study needed transfusion of red blood cell concentrates, there was a total avoidance of perioperative transfusion of fresh frozen plasma and a reduction in transfused platelets (one of nine children vs nine of 36 children in the historic group) after implementation of the PBM strategy. Based on a predefined ROTEM(®) threshold in the PBM group (FibTEM MCF <8 mm), administration of fibrinogen concentrate was necessary in all of these children. The mean total costs per patient consisting of transfused allogeneic blood products and coagulation factor concentrates were reduced by 17.1% after implementation of PBM (1071.82 EUR per patient before vs 888.93 EUR after implementation).

CONCLUSIONS

The implementation of a ROTEM(®) -assisted PBM is feasible and is associated with a considerable reduction in intraoperative transfusion requirements and thereby a decrease in transfusion-related direct costs.

Beyond the platelet count: immature platelet fraction and thromboelastometry correlate with bleeding in patients with immune thrombocytopenia

Platelet counts (PC) estimate bleeding risk in Immune Thrombocytopenia (ITP). We investigated whether measures of thromboelastometry and absolute immature platelet fraction (A-IPF) would correlate better with acute bleeding score (ABS) than PC or mean platelet volume (MPV). Simultaneous determination of ABS, complete blood count and thromboelastometry was performed in 141 ITP patients; 112 underwent A-IPF testing. Subgroup analyses were performed for paediatric subjects, PC <60 × 10(9) /l and <30 × 10(9) /l. PC significantly inversely correlated with ABS in all subjects, PC <30 × 10(9) /l and total paediatric cohort. MPV did not correlate with ABS in any subgroup. Thromboelastometry measures of clot firmness, but not PC, significantly correlated with ABS in all subjects with PC <60 × 10(9) /l, and children with PC <60 × 10(9) /l and <30 × 10(9) /l. A-IPF demonstrated stronger correlation with ABS than did PC among all subjects, those with PC <60 × 10(9) /l, all children and children with PC <30 × 10(9) /l (r = -0·37; r = -0·34; r = -0·44; r = -0·60) versus ABS with PC (r = -0·36; ns; r = -0·32; ns). Stronger correlations of both thromboelastometry measures of clot firmness and A-IPF than PC with ABS suggest factors beyond PC, i.e. related to platelet function, contribute to ITP bleeding pathophysiology. Thromboelastometry, A-IPF and ABS can be incorporated into routine or acute visits.

Management of hemorrhage in cardiothoracic surgery

Bleeding is an important issue in cardiothoracic surgery, and about 20% of all blood products are transfused in this clinical setting worldwide. Transfusion practices, however, are highly variable among different hospitals and more than 25% of allogeneic blood transfusions have been considered inappropriate. Furthermore, both bleeding and allogeneic blood transfusion are associated with increased morbidity, mortality, and hospital costs. In the past decades, several attempts have been made to find a universal hemostatic agent to ensure hemostasis during and after cardiothoracic surgery. Most drugs studied in this context have either failed to reduce bleeding and transfusion requirements or were associated with severe adverse events, such as acute renal failure or thrombotic/thromboembolic events and, in some cases, increased mortality. Therefore, an individualized goal-directed hemostatic therapy ("theranostic" approach) seems to be more appropriate to stop bleeding in this complex clinical setting. The use of point-of-care (POC) transfusion and coagulation management algorithms guided by viscoelastic tests such as thromboelastometry/thromboelastography in combination with POC platelet function tests such as whole blood impedance aggregometry, and based on first-line therapy with fibrinogen and prothrombin complex concentrate have been associated with reduced allogeneic blood transfusion requirements, reduced incidence of thrombotic/thromboembolic and transfusion-related adverse events, and improved outcomes in cardiac surgery. This article reviews the current literature dealing with the management of hemorrhage in cardiothoracic surgery based on POC diagnostics and with specific coagulation factor concentrates and its impact on transfusion requirements and patients' outcomes.

Reappearance of circulating heparin in whole blood heparin concentration-based management does not correlate with postoperative bleeding after cardiac surgery

OBJECTIVE

The Hepcon Heparin Management System (HMS) facilitates administration of higher heparin and lower protamine doses, which may affect bleeding potential due to heparin rebound. The present study evaluated heparin rebound in patients for whom the Hepcon HMS was used to determine whether point-of-care tests detect residual heparin and residual heparin is associated with postoperative blood loss.

DESIGN

Prospective study.

SETTING

Tertiary care center affiliated with a university hospital.

PARTICIPANTS

Adults undergoing elective cardiac surgery requiring cardiopulmonary bypass.

INTERVENTIONS

In blood samples obtained at baseline, at 2 minutes, and at 1, 2, 4, 6, and 24 hours after heparin neutralization, heparin concentrations were measured using an automated chromogenic assay. Activated coagulation time (ACT), activated partial thromboplastin time (APTT), and thromboelastometry 2 hours after heparin neutralization also were examined in the last 22 study patients enrolled.

MEASUREMENTS AND MAIN RESULTS

All 31 patients had measurable heparin levels 2 hours after protamine administration; 22 patients exhibited a primary failure to reverse heparin after protamine administration, and 9 patients had measureable heparin levels 2 hours after complete heparin reversal (ie, heparin rebound). The thromboelastometric variable, INTEM-CT:HEPTEM-CT ratio, correlated with heparin concentration (r=0.72), but ACT (r=-0.12), APTT (r=0.36), and whole blood heparin concentration, determined using the Hepcon HMS, did not. Peak heparin concentration (0.18±0.07 U/mL) at 4 hours was not correlated with mediastinal blood loss.

CONCLUSION

Circulating heparin detected by the chromogenic assay was too low to be clinically significant based on postoperative bleeding, although all 31 patients had residual heparin or heparin rebound at 2 hours after protamine administration with use of the Hepcon HMS.

Biochemical and biological characterization of Naja kaouthia venom from North-East India and its neutralization by polyvalent antivenom

This study describes biochemical and biological properties of Naja kaouthia (Indian monocled cobra) venom of North-East India. The LD50 of the crude venom was found to be 0.148mg/kg and neurotoxicitic symptoms like paralysis of lower limbs and heavy difficulty in breathing at sub-lethal dose in mice was observed. The venom exhibited PLA2, indirect hemolytic and myotoxic activities but showed weak proteolytic and low direct hemolytic activities. It did not exhibit any hemorrhage when injected intradermally to mice. Anticoagulant activity was prominent when recalcification, prothrombin and activated partial thrombinplastin time were tested on platelet poor plasma. Rotem analysis of whole citrated blood in presence of venom showed delay in coagulation time and clot formation time. Fibrinogen of whole citrated blood was depleted by venom when analyzed in Sonoclot. Crude venom at 10µg and after 16hr of incubation was found to degrade α chain of fibrinogen. Neutralization study showed that Indian polyvalent antivenom could neutralize some of the biochemical and biological activities as well as its fibrinogenolytic activity.

Five-minute parameter of thromboelastometry is sufficient to detect thrombocytopenia and hypofibrinogenaemia in patients undergoing liver transplantation

BACKGROUND

Early detection of coagulopathy is important to prevent bleeding during liver transplantation (LT). Rotation thromboelastometry (ROTEM(®)) provides the earliest parameter of clot amplitudes at 5 min (A5). We evaluated whether A5 correlates with platelet count (PLT) and fibrinogen concentration (Fib) and can predict thrombocytopenia and hypofibrinogenaemia in hypocoagulable patients undergoing living-donor LT (LDLT).

METHODS

A total of 3446 retrospective ROTEM(®) measurements, including 1139 EXTEM, 1182 INTEM, and 1125 FIBTEM, with simultaneously measured PLT and Fib, were analysed during LDLT in 239 patients. The correlations between A5 and maximum clot firmness (MCF) index, PLT, and Fib were calculated. Receiver operating characteristic analysis with area under the curve (AUC) was used to assess A5 thresholds predictive of PLT and Fib.

RESULTS

The median PLT was 47 000 mm(-3) and the median Fib was 100 mg dl(-1) during LDLT. The A5 parameters of EXTEM (A5EXTEM) and INTEM (A5INTEM) were highly correlated with MCF (r=0.96 and r=0.95, respectively), PLT (r=0.76 and r=0.77, respectively), and Fib (r=0.63 and r=0.64, respectively). A5 of FIBTEM (A5FIBTEM) was also correlated with MCF (r=0.91) and Fib (r=0.75). A5EXTEM thresholds of 15 and 19 mm predicted PLT<30 000 mm(-3) (AUC=0.90) and <50 000 mm(-3) (AUC=0.87), respectively, whereas A5FIBTEM 4 mm predicted Fib<100 mg dl(-1) (AUC=0.86). Biases from A5EXTEM and A5FIBTEM to their MCFs were 16.4 and 1.3 mm, respectively.

CONCLUSIONS

A5 as an early variable of clot firmness is effective in detecting critically low PLT and Fib. A5 can therefore be a reliable fast index guiding transfusion therapy in hypocoagulable patients undergoing LDLT.

Clinical utility of viscoelastic tests of coagulation in patients with liver disease

The prothrombin time (PT) and international normalised ratio (INR) are used in scoring systems (Child-Pugh, MELD, UKELD) in chronic liver disease and as a prognostic tool and for dynamic monitoring of hepatic function in acute liver disease. These tests are known to be poor predictors of bleeding risk in liver disease; however, they continue to influence clinical management decisions. Recent work on coagulation in liver disease, in particular thrombin generation studies, has led to a paradigm shift in our understanding and it is now recognised that haemostasis is relatively well preserved. Whole blood global viscoelastic tests (TEG(®) /ROTEM(®) ) produce a composite dynamic picture of the entire coagulation process and have the potential to provide more clinically relevant information in patients with liver disease. We performed a systematic review of all relevant studies that have used viscoelastic tests (VET) of coagulation in patients with liver disease. Although many studies are observational and small in size, it is clear that VET provide additional information that is in keeping with the new concepts of how coagulation is altered in these patients. This review provides the basis for large scale, prospective outcome studies to establish the clinical value of these tests.

Trends in trauma transfusion

Trauma is the leading cause of death in young adults and acute blood loss contributes to a large portion of mortality in the early post-trauma period. The recognition of lethal triad of coagulopathy, hypothermia and acidosis has led to the concepts of damage control surgery and resuscitation. Recent experience with managing polytrauma victims from the Iraq and Afghanistan wars has led to a few significant changes in clinical practice. Simultaneously, transfusion practices in the civilian settings have also been extensively studied retrospectively and prospectively in the last decade. Early treatment of coagulopathy with a high ratio of fresh frozen plasma and platelets to packed red blood cells (FFP:platelet:RBC), prevention and early correction of hypothermia and acidosis, monitoring of hemostasis using point of care tests like thromoboelastometry, use of recombinant activated factor VII, antifibrinolytic drugs like tranexamic acid are just some of the emerging trends. Further studies, especially in the civilian trauma centers, are needed to confirm the lessons learned in the military environment. Identification of patients likely to need massive transfusion followed by immediate preventive and therapeutic interventions to prevent the development of coagulopathy could help in reducing the morbidity and mortality associated with uncontrolled hemorrhage in trauma patients.