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

The evolving knowledge on primary hemostasis in patients with cirrhosis: A comprehensive review

Patients with cirrhosis develop complex alterations in primary hemostasis that include both hypocoagulable and hypercoagulable features. This includes thrombocytopenia, multiple alterations of platelet function, and increased plasma levels of von Willebrand factor. Contrary to the historical view that platelet dysfunction in cirrhosis might be responsible for an increased bleeding tendency, the current theory posits a rebalanced hemostasis in patients with cirrhosis. Severe thrombocytopenia is not indicative of the bleeding risk in patients undergoing invasive procedures and does not dictate per se the need for pre-procedural prophylaxis. A more comprehensive and individualized risk assessment should combine hemostatic impairment, the severity of decompensation and systemic inflammation, and the presence of additional factors that may impair platelet function, such as acute kidney injury and bacterial infections. Although there are multiple, complex alterations of platelet function in cirrhosis, their net effect is not yet fully understood. More investigations evaluating the association between alterations of platelet function and bleeding/thrombosis may improve risk stratification in patients with decompensated cirrhosis. Besides hemostasis, the assessment of von Willebrand factor Ag and ADP-induced, whole-blood platelet aggregation normalized by platelet count (VITRO score and PLT ratio) are promising biomarkers to predict the risk of hepatic decompensation and survival in both compensated and decompensated patients. Further investigations into the in vivo interplay between platelets, circulating blood elements, and endothelial cells may help advance our understanding of cirrhotic coagulopathy. Here, we review the complex changes in platelets and primary hemostasis in cirrhosis and their potential clinical implications.

Navigating the Labyrinth: Intensive Care Challenges for Patients with Acute-on-Chronic Liver Failure

Acute-on-chronic liver failure (ACLF) refers to the deterioration of liver function in individuals who already have chronic liver disease. In the setting of ACLF, liver damage leads to the failure of other organs and is associated with increased short-term mortality. Optimal medical management of patients with ACLF requires implementing complex treatment strategies, often in an intensive care unit (ICU). Failure of organs other than the liver distinguishes ACLF from other critical illnesses. Although there is growing evidence supporting the current approach to ACLF management, the mortality associated with this condition remains unacceptably high. In this review, we discuss considerations for ICU care of patients with ACLF and highlight areas for further research.

Rotational ThromboElastometry-guided blood component administration versus standard of care in patients with Cirrhosis and coagulopathy undergoing Invasive ProcEdures (RECIPE): study protocol for a randomised controlled trial

BACKGROUND

Patients with cirrhosis often undergo invasive procedures both for management of complications of their advanced liver disease, including treatment for hepatocellular carcinoma, as well as underlying comorbidities. Despite a current understanding that most patients with cirrhosis are in a rebalanced haemostatic state (despite abnormalities in conventional coagulation tests, namely INR and platelet count), patients with cirrhosis are still often given prophylactic blood components based on these conventional parameters, in an effort to reduce procedure-related bleeding. Viscoelastic tests such as Rotational Thromboelastometry (ROTEM) provide a global measurement of haemostasis and have been shown to predict bleeding risk more accurately than conventional coagulation tests, and better guide blood product transfusion in a number of surgical and trauma-related settings. The aim of this study is to assess the utility of a ROTEM-based algorithm to guide prophylactic blood component delivery in patients with cirrhosis undergoing invasive procedures. We hypothesise that ROTEM-based decision-making will lead to a reduction in pre-procedural blood component usage, particularly fresh frozen plasma (FFP), compared with standard of care, whilst maintaining optimal clinical outcomes.

METHODS

This is a multi-centre randomised controlled trial comparing ROTEM-guided prophylactic blood component administration to standard of care in patients with cirrhosis and coagulopathy undergoing invasive procedures. The primary efficacy outcome of the trial is the proportion of procedures requiring prophylactic transfusion, with the primary safety outcome being procedure-related bleeding complications. Secondary outcomes include the amount of blood products (FFP, platelets, cryoprecipitate) transfused, transfusion-related side effects, procedure-related complications other than bleeding, hospital length of stay and survival.

DISCUSSION

We anticipate that this project will lead to improved prognostication of patients with cirrhosis, in terms of their peri-procedural bleeding risk. We hope to show that a significant proportion of cirrhotic patients, deemed coagulopathic on the basis of standard coagulation tests such as INR and platelet count, are actually in a haemostatic balance and thus do not require prophylactic blood product, leading to decreased and more efficient blood component use.

TRIAL REGISTRATION

RECIPE has been prospectively registered with the Australia and New Zealand Clinical Trials Registry on the 30th April 2019 ( ACTRN12619000644167 ).

Viscoelastic Testing Prior to Non-surgical Procedures Reduces Blood Product Use Without Increasing Bleeding Risk in Cirrhosis

BACKGROUND/AIMS

Thromboelastography (TEG) and Rotational Thromboelastometry (ROTEM) analyze hemostatic function in patients with coagulopathy. We sought to quantify the impact of TEG and ROTEM-guided transfusion algorithms on blood product utilization in patients with cirrhosis undergoing non-surgical procedures.

METHODS

We performed a systematic review and meta-analysis on the utility of viscoelastic testing prior to non-surgical procedures to determine their impact on pre-procedural blood product use and post-procedural bleeding events. Studies comparing TEG or ROTEM-guided transfusions with standard-of-care (SOC) prior to non-surgical procedures in adult patients with cirrhosis were included. Primary outcomes were fresh frozen plasma (FFP) and platelet transfusion and secondary outcomes of post-procedure bleeding, transfusion-related complications, and mortality; and were reported as standardized mean differences (SMD) and risk ratios (RR).

RESULTS

Six studies (five randomized controlled trials and one cohort study) involving 367 patients met inclusion criteria. Compared with SOC, TEG/ROTEM-guided transfusions led to an overall decreased number of patients who received FFP transfusions (SMD = -0.93, 95% CI [-1.54, -0.33], p < 0.001) and platelets transfusions (SMD = -1.50, CI [-1.85, -1.15], p < 0.001). Total amount of FFP (SMD-0.86, p < 0.001) and platelet (SMD = -0.99, p < 0.001) transfused in the TEG/ROTEM group were also lower. Decreased pre-procedure transfusion in the TEG/ROTEM group did not result in increased post-procedure bleeding (RR = 0.61, p = 0.09) or in mortality (RR = 0.91, p = 0.93).

CONCLUSION

In patients with cirrhosis, TEG or ROTEM significantly reduces blood product utilization prior to non-surgical procedures, with no increase in post-procedure bleeding or mortality. TEG and ROTEM utilization can promote high-value care and improve transfusion stewardship in this population.

Procedural bleeding risk, rather than conventional coagulation tests, predicts procedure related bleeding in cirrhosis

BACKGROUND

Standard coagulation parameters are used to guide prophylactic blood product transfusion prior to invasive procedures in cirrhotic patients despite limited high-quality evidence.

AIMS

We aimed to describe coagulation parameters and prophylactic blood product use in cirrhotic patients having invasive procedures, and the influence of both on periprocedural bleeding.

METHODS

We conducted a cohort study of cirrhotic patients undergoing invasive procedures at a referral hospital. Procedures were classified into low or moderate-high bleeding risk. Prophylactic blood component was defined as fresh frozen plasma, cryoprecipitate or platelet transfusion prior to procedures. Univariate and multivariate logistic regression was performed to identify factors associated with procedure-related bleeding.

RESULTS

We identified 566 procedures in 233 cirrhotic patients. Prophylactic blood product was given before 16% of high-risk and 11% of low-risk procedures (P = 0.18). Eight (8.3%) high-risk procedures were complicated by postprocedural bleeding, six of which occurred in patients without significant coagulopathy. The bleeding rate for low-risk procedures was 0.4%. For patients with international normalized ratio >1.5, platelet count <50 x 109/L, or both, the rate of bleeding was comparable between those given and not given prophylactic blood products (3.1 vs. 1.9%; P = 0.63). After adjusting for age, sex, platelet count, international normalized ratio, acute kidney injury, sepsis and model of end-stage liver disease, the only factor significantly predicting procedure-related bleeding was the procedural bleeding risk category (P < 0.01).

CONCLUSIONS

Procedure-related bleeding in cirrhotic patients cannot be accurately predicted by INR or platelet count, nor prevented by blood component prophylaxis using these parameters. Procedure-related bleeding is best predicted by the bleeding risk status of procedures.

Cryoprecipitate as an alternative to platelet transfusion in thrombocytopenia

Platelet transfusions are not always available for bleeding in severe thrombocytopenia, as storage outside of major centers is limited by their short shelf-life. Data are lacking to support alternative available blood products; however, additional fibrinogen has been shown to enhance clot formation in vitro. To test the hypothesis that cryoprecipitate supplementation could improve clot formation in severe thrombocytopenia, eight hematological malignancy patients with platelet counts under 10 × 109/L each had 10 units of apheresis cryoprecipitate transfused prior to planned prophylactic platelet transfusions. The primary endpoint of thromboelastometry amplitude at 20 min increased by a mean of 5.1 mm (p < 0.01) following cryoprecipitate transfusion despite persisting thrombocytopenia. Thromboelastometry clotting times reduced by a mean of 7.8 s (p < 0.05) and alpha angle increased by a mean of 10.6⁰ (p < 0.01). These results are consistent with cryoprecipitate enhancing the strength of the fibrin/platelet meshwork within the forming thrombus. While platelet transfusion remains the standard of care, where platelet supplies are limited, these data provide a rationale for the use of cryoprecipitate to obtain hemostasis in bleeding thrombocytopenic patients.

Intensive care management of acute-on-chronic liver failure

The syndrome of acute-on-chronic liver failure combines deterioration of liver function in a patient with chronic liver disease, with the development of extrahepatic organ failure and high short-term mortality. Its successful management demands a rapid and coherent response to the development of dysfunction and failure of multiple organ systems in an intensive care unit setting. This response recognises the features that distinguish it from other critical illness and addresses the complex interplay between the precipitating insult, the many organ systems involved and the disordered physiology of underlying chronic liver disease. An evidence base is building to support the approaches currently adopted and outcomes for patients with this condition are improving, but mortality remains unacceptably high. Herein, we review practical considerations in critical care management, as well as discussing key knowledge gaps and areas of controversy that require further focussed research.

Viscoelastic tests in liver disease: where do we stand now?

Hemostasis is a complex physiological process based on the balance between pro-coagulant and anticoagulant systems to avoid pathological bleeding or thrombosis. The changes in standard coagulation tests in liver disease were assumed to reflect an acquired bleeding disorder, and cirrhotic patients were considered naturally anticoagulated. In the light of the new evidence, the theory of rebalanced hemostasis replaced the old concept. According to this model, the hemostatic alteration leads to a unique balance between pro-coagulant, anticoagulant, and fibrinolytic systems. But the balance is fragile and may prone to bleeding or thrombosis depending on various risk factors. The standard coagulation tests [INR (international normalized ratio), platelet count and fibrinogen] only explore parts of the hemostasis, not offering an entire image of the process. Rotational thromboelastometry (ROTEM) and thromboelastography (TEG) are both point of care viscoelastic tests (VET) that provide real-time and dynamic information about the entire hemostasis process, including clot initiation (thrombin generation), clot kinetics, clot strength, and clot stability (lysis). Despite prolonged PT/INR (international normalized ratio of prothrombin time) and low platelet counts, VET is within the normal range in many patients with both acute and chronic liver disease. However, bleeding remains the dominant clinical issue in patients with liver diseases, especially when invasive interventions are required. VET has been shown to asses more appropriately the risk of bleeding than conventional laboratory tests, leading to decrial use of blood products transfusion. Inappropriate clotting is common but often subtle and may be challenging to predict even with the help of VET. Although VET has shown its benefit, more studies are needed to establish cut-off values for TEG and ROTEM in these populations and standardization of transfusion guidelines before invasive interventions in cirrhotic patients/orthotopic liver transplantation.

Comparison of Thromboelastography and Conventional Coagulation Tests in Patients With Severe Liver Disease

OBJECTIVE

Thromboelastography (TEG) may provide rapid and clinically important coagulation information in acutely ill patients with chronic liver disease (CLD). Our objective was to describe the relationship between TEG and conventional coagulation tests (CCTs), which has not been previously explored in this population.

METHODS

In acutely ill patients with severe CLD (Child-Pugh score > 9, category C), we conducted a prospective observational study investigating coagulation assessment as measured by both CCTs and TEG. We used quantile regression to explore 30 associations between TEG parameters and corresponding CCTs. We compared TEG and CCT measures of coagulation initiation, clot formation, clot strength, and fibrinolysis.

RESULTS

We studied 34 patients on a total of 109 occasions. We observed inconsistent associations between TEG and CCT measures of coagulation initiation: TEG (citrated kaolin [CK] assay) standard reaction time and international normalized ratio: R ² = 0.117 (P = .044). Conversely, there were strong and consistent associations between tests of clot formation: TEG (CK) kinetics time and fibrinogen: R ² = 0.202 (P < .0001) and TEG (CK) α angle and fibrinogen 0.263 (P < .0001). We also observed strong associations between tests of clot strength, specifically TEG MA and conventional fibrinogen levels, across all TEG assays: MA (CK) and fibrinogen: R ² = 0.485 (P < .0001). There were no associations between TEG and D-dimer levels.

CONCLUSIONS

In acutely ill patients with CLD, there are strong and consistent associations between TEG measures of clot formation and clot strength and conventional fibrinogen levels. There are weak and/or inconsistent associations between TEG and all other conventional measures of coagulation.

Tracheostomy in critically ill liver disease patients with coagulopathy: A retrospective study at a tertiary center

Introduction

Critically ill patients with liver disease commonly present to the intensive care unit (ICU) with need for prolonged ventilation, difficult weaning, and refractory coagulopathy. These patients experience both bleeding and thrombotic complications with a precariously balanced state of coagulopathy. The purpose of this study was to assess the bleeding complications of tracheostomy in critically ill patients with liver disease.

Methods

A retrospective study was conducted in liver ICU of a tertiary teaching institute. Medical records were analyzed to assess postprocedure complication rate among 73 critically ill liver disease patients who had undergone tracheostomy during the period of October 2017 to September 2018.

Results

Ten out of 73 patients (13%) required transfusion of blood products after 12 h of procedure, despite thromboelastography (TEG)-based correction prior to procedure. Of these, 7 patients (9%) underwent surgical tracheostomy (ST) and three patients (4%) underwent percutaneous tracheostomy. Statistically no significant difference in bleeding was seen among the two groups, but a rising trend was seen with the ST group (P = 0.52). None of the patients experienced procedure-related pneumothorax and subcutaneous emphysema, as observed in the chest X-ray.

Conclusion

We conclude that coagulopathy should not be deterrence for the performance of tracheostomy in critically ill patients with liver disease. Adequate clotting support guided by the global tests of coagulation, such as TEG, ensures lesser incidence of bleeding.

Clinical utility of viscoelastic testing in chronic liver disease: A systematic review

BACKGROUND

Conventional coagulation tests are widely used in chronic liver disease to assess haemostasis and to guide blood product transfusion. This is despite the fact that conventional tests do not reliably separate those with a clinically significant coagulopathy from those who do not. Viscoelastic testing such as thromboelastography (TEG) correlate with bleeding risk and are more accurate in identifying those who will benefit from blood product transfusion. Despite this, viscoelastic tests have not been widely used in patients with chronic liver disease outside the transplant setting.

AIM

To assess the utility of Viscoelastic Testing guided transfusion in chronic liver disease patients presenting with bleeding or who require an invasive procedure.

METHODS

PubMed and Google Scholar searches were performed using the key words “thromboelastography”, “TEG” or “viscoelastic” and “liver transplantation”, “cirrhosis” or “liver disease” and “transfusion”, “haemostasis”, “blood management” or “haemorrhage”. A full text review was undertaken and data was extracted from randomised control trials that evaluated the outcomes of viscoelastic test guided transfusion in those with liver disease. The study subjects, inclusion and exclusion criteria, methods, outcomes and length of follow up were examined. Data was extracted by two independent individuals using a standardized collection form. The risk of bias was assessed in the included studies.

RESULTS

A total of five randomised control trials included in the analysis examined the use of TEG guided blood product transfusion in cirrhosis prior to invasive procedures (n = 118), non-variceal haemorrhage (n = 96), variceal haemorrhage (n = 60) and liver transplantation (n = 28). TEG guided transfusion was effective in all five studies with a statistically significant reduction in overall blood product transfusion compared to standard of care. Four of the five studies reported a significant reduction in transfusion of fresh frozen plasma and platelets. Two studies showed a significant reduction in cryoprecipitate transfusion. No increased risk of bleeding was reported in the three trials where TEG was used perioperatively or prior to an invasive procedure. Two trials in the setting of cirrhotic variceal and non-variceal bleeding showed no difference in control of initial bleeding. In those with variceal bleeding, there was a statistically significant reduction in rate of re-bleeding at 42 d in the TEG arm 10% (vs 26.7% in the standard of care arm P = 0.012). Mortality data reported at various time points for all five trials from 6 wk up to 3 years was not statistically different between each arm. One trial in the setting of non-variceal bleeding demonstrated a significant reduction in adverse transfusion events in the TEG arm 30.6% (vs 74.5% in the control arm P < 0.01). In this study there was no significant difference in total hospital stay although length of stay in intensive care unit was reduced by an average of 2 d in the TEG arm (P = 0.012).

CONCLUSION

Viscoelastic testing has been shown to reduce blood product usage in chronic liver disease without compromising safety and may enable guidelines to be developed to ensure patients with liver disease are optimally managed.

Viscoelastic Tests as Point-of-Care Tests in the Assessment and Management of Bleeding and Thrombosis in Liver Disease

Viscoelastic point-of-care (VET POC) tests provide a global assessment of hemostasis and have an increasing role in the management of bleeding and blood component delivery across several clinical settings. VET POC tests have a rapid turnaround time, provide a better overall picture of hemostasis, predict bleeding more accurately than conventional coagulation tests, and reduce blood component usage and health care costs. Despite commonly having abnormal conventional coagulation tests, most patients with chronic liver disease have a "rebalanced" hemostasis. However, this hemostatic balance is delicate and these patients are predisposed to both bleeding and thromboembolic events. Over recent years, VET POC tests have been increasingly studied for their potential as better functional tests of hemostasis in liver disease patients. This review provides a background on the most common VET POC tests (thromboelastography and rotational thromboelastometry) and discusses the current evidence for these tests in the prediction and management of bleeding and thrombosis in patients with chronic liver disease, and in liver resection and transplant. With the recent publication of several randomized controlled trials, there is growing evidence that VET POC tests may be used to improve bleeding risk assessment and reduce blood product use in liver disease patients outside of the transplant setting. However, consensus is still lacking regarding the VET POC tests' thresholds that should be used to trigger blood product transfusion. VET POC tests also show promise in predicting thrombosis in patients with liver disease, but further research is needed before they can be used to guide anticoagulant therapy.

Rotational thrombelastometry (ROTEM) improves hemostasis assessment compared to conventional coagulation test in ACLF and Non-ACLF patients

Background

Patients with liver cirrhosis typically exhibit abnormal coagulation parameters in conventional coagulation tests (CCTs). Rotational thromboelastometry (ROTEM) is a holistic blood coagulation assay. This method provides an insight into the global hemostatic capabilities and has been suggested to provide a better overview of the coagulation system in liver cirrhosis.

Methods

The goal of this study was to examine hemostasis in patients with stable liver cirrhosis (Non-ACLF) and in acute-on-chronic liver failure (ACLF) by CCT and ROTEM including agreement of both tests and the prospective assessment of test performance based on clinical outcomes in ACLF patients. Therefore, ACLF patients were additionally subgrouped by bleeding events. Fifty-five Non-ACLF patients and twenty-two patients with ACLF were analysed in this prospective cohort study.

Results

Coagulation parameters analysed by CCT were outside the normal range in Non-ACLF and ACLF patients, but were significantly more aberrant in ACLF patients. Non-ACLF patients analysed by ROTEM revealed parameters largely within the normal limits, while significantly more ROTEM parameters in ACLF patients were affected. Maximum clot firmness (MCF) was significantly divergent between both patient groups and correlated well with levels of fibrinogen and platelet count. Using Cohen’s Kappa coefficient κ, the strength of agreement between CCT and ROTEM analyses was determined to be fair for Non-ACLF patients and moderate for ACLF patients. Bleeding events occurred significantly more often in ACLF group with significantly reduced A10 and MCF.

Conclusions

For assessing hemostasis in Non-ACLF and ACLF patients the underlying dataset shows advantages of ROTEM over CCT. A10 and MCF represent suitable prognostic parameters in predicting bleeding events in ACLF group.

Clinical Implications of Thrombocytopenia for the Cirrhotic Patient

Thrombocytopenia is a frequent complication in patients with cirrhosis. As many as 84% of patients with cirrhosis have thrombocytopenia, and it is an independent variable indicative of advanced disease and poor prognosis. Although there is great concern that it may aggravate bleeding during surgical procedures, there is limited evidence to inform decisions regarding the treatment of cirrhotic patients with thrombocytopenia undergoing invasive procedures. Finally, there is evidence that platelets play a significant role in liver regeneration. In this report, the clinical implications of thrombocytopenia in cirrhotic patients are reviewed. The utility of platelet counts in the prognosis of cirrhosis and relationship to complications of advanced liver disease, including portal hypertension, esophageal varices, and hepatocellular carcinoma. The impact of low platelet counts on bleeding complications during invasive procedures is outlined. Finally, the role of platelets and potential adverse impact in liver regeneration is reviewed.

Liver function after transplantation in the assessment of the coagulation system and the concept of antithrombotic therapy

Introduction

Thrombotic complications after liver transplantation limit the long-term success of the procedure. Therefore, an early and accurate diagnosis with the appropriate treatment is crucial to sustain the proper functioning of the graft.

Aim

To evaluate the return of newly transplanted liver function within the first days of ICU stay after liver transplantation surgery (Ltx) observed in laboratory examination. It is important to understand the physiology of the newly transplanted liver, particularly in terms of its metabolic function and the assessment of easy-to-monitor coagulation parameters and enzyme markers.

Material and methods

We present our observations carried out in 27 patients, transplanted in the period 2015-2017, during their stay in the Department of Anaesthesiology and Intensive Therapy of the University Hospital in Wroclaw. We demonstrated changes in laboratory parameters within 72 h after liver transplantation and the concept of anticoagulant therapy at our institution.

Results

The presented results show the characteristics of aspartate transaminase, alanine transaminase, bilirubin, and standard tests evaluating the coagulation system within the first 4 days after surgery. The concept of anticoagulant therapy used in our intensive care unit is also presented. The aim of the work is an observation of physiology of the graft function in the aspect of coagulation disorders.

Conclusions

The early postoperative period is considered prognostic. The characteristics of basic biochemical tests are determined by the function of the transplanted organ. Implementation of anticoagulant therapy in this period is a therapeutic challenge that requires experience.

Assessment and management of coagulopathy in critically-ill patients with liver failure

PURPOSE OF REVIEW

This review provides insight into our current understanding of the pathophysiology and treatment of coagulopathy associated with liver failure, and bleeding risk assessment.

RECENT FINDINGS

Patients with end-stage liver disease (ESLD) have a rebalanced coagulation profile and are at risk for both excessive clotting and bleeding. Hypercoagulability is associated with profound endothelial dysfunction and an increased concentration of liver-independent coagulation factors. Because of this rebalanced coagulation profile, standard laboratory tests have been demonstrated to be ineffective in either predicting and/or guiding the management of coagulopathy. Viscoelastic testing, however, is able to provide a dynamic assessment of clot formation in whole blood and has been demonstrated to be invaluable in both monitoring and management of coagulation problems associated with liver failure. More recently, there is increasing interest in thrombin generation tests to monitor coagulation in patients with ESLD.Multiple institutional protocols for prophylaxis and treatment of ESLD-related thromboses have been developed. High-quality studies evaluating these approaches are lacking.

SUMMARY

Patients with ESLD are at risk for excessive bleeding and clotting. Treatment of any significant coagulopathy should not be based solely on standard laboratory tests. Thrombosis prophylaxis has to be considered in susceptible populations.

Real-Time Ultrasound-Guided Paracentesis by Radiologists: Near Zero Risk of Hemorrhage without Correction of Coagulopathy

PURPOSE

To evaluate the rate and risk factors for hemorrhage in patients undergoing real-time, ultrasound-guided paracentesis by radiologists without correction of coagulopathy.

MATERIALS AND METHODS

This was a retrospective study of all patients who underwent real-time, ultrasound-guided paracentesis at a single institution over a 2-year period. In total, 3116 paracentesis procedures were performed: 757 (24%) inpatients and 2,359 (76%) outpatients. Ninety-five percent of patients had a diagnosis of cirrhosis. Mean patient age was 56.6 years. Mean international normalized ratio (INR) was 1.6; INR was > 2 in 437 (14%) of cases. Mean platelet count was 122 x 10³/μL; platelet count was < 50 x 10³/μL in 368 (12%) of patients. Seven hundred seven (23%) patients were dialysis dependent. Patients were followed for 2 weeks after paracentesis to assess for hemorrhage requiring transfusion or rescue angiogram/embolization. Univariate analysis was performed to determine risk factors for hemorrhage. Blood product and cost saving analysis were performed.

RESULTS

Significant post-paracentesis hemorrhage occurred in 6 (0.19%) patients, and only 1 patient required an angiogram with embolization. No predictors of post-procedure bleeding were found, including INR and platelet count. Transfusion of 1125 units of fresh frozen plasma and 366 units of platelets were avoided, for a transfusion-associated cost savings of $816,000.

CONCLUSIONS

Without correction of coagulation abnormalities with prophylactic blood product transfusion, post-procedural hemorrhage is very rare when paracentesis is performed with real-time ultrasound guidance by radiologists.

Point-of-care Testing of Coagulation in Intensive Care Unit: Role of Thromboelastography

How to cite this article: Govil D, Pal D. Point-of-care Testing of Coagulation in Intensive Care Unit: Role of Thromboelastography. Indian J Crit Care Med 2019;23(Suppl 3):S202–S206.

Hypercoagulability in End-stage Liver Disease: Review of Epidemiology, Etiology, and Management

In this review, we analyze the epidemiology of thromboses related to end-stage liver disease (ESLD), discuss causes of hypercoagulability, describe susceptible populations, and critically evaluate proposed prophylaxis and treatment of thromboses. Classically, ESLD has been regarded as a model for coagulopathy, and patients were deemed to be at high risk for bleeding complications. Patients with ESLD are not auto-anticoagulated, and they do not have a lower risk of portal vein thrombosis, intracardiac thrombus formation, pulmonary embolism or hepatic artery thrombosis. Though the cause of hypercoagulability is multifactorial, endothelial dysfunction likely plays a central role for all patients with ESLD. Some subpopulations, such as patients with nonalcoholic steatohepatitis and autoimmune conditions, are at increased risk of thrombotic events as are patients of Hispanic ethnicity. The science behind prophylaxis of different types of clotting and treatment of thromboses is developing rapidly. A number of medications, including low molecular weight heparin, unfractionated heparin, aspirin, vitamin K antagonists, and direct oral anticoagulants can be used, but clear guidelines are lacking. Acute intraoperative clotting can be associated with high mortality. Routine use of transesophageal echocardiography can be helpful in early recognition and treatment of intraoperative thrombosis. Heparin should be reserved for cases of intracardiac thrombus/pulmonary embolism without hemodynamic instability. In unstable patients, low dose of recombinant tissue plasminogen activator can be used. In this new era of heightened awareness of thrombotic events in ESLD patients, prospective randomized trials are urgently needed to best guide clinical practice.

A retrospective analysis of re-exploration after living donor right lobe liver transplantation: incidence, causes, outcomes, and risk factors

Despite technical difficulties, right lobe liver grafting is preferred in living donor liver transplantation because of the graft size. Re-exploration after living donor right lobe liver transplantation (LRLT) has never been separately analyzed. We aimed to analyze the incidence, causes, outcomes, and risk factors of re-exploration after LRLT. We reviewed medical records of 1016 LRLT recipients from October 2003 to July 2017 and identified recipients who underwent re-exploration within hospital stay. Separate analyses were also performed according to cause of re-exploration. The overall incidence of re-exploration was 17.0% (173/1016). The most common cause of re-exploration was bleeding (50%). Overall re-exploration was associated with clinical outcome, but different results were shown on analyses according to cause of re-exploration. Risk factors of re-exploration were underlying hepatocellular carcinoma and operative duration [Odds ratio (OR), 1.49; 95% confidence interval (CI), 1.05-2.12; P = 0.03, and OR, 1.002; 95% CI, 1.001-1.004; P = 0.0023, respectively]. Re-exploration after LRLT is relatively common, and is strongly associated with mortality and graft failure.

Strategies to avoid empiric blood product administration in liver transplant surgery

Massive blood loss has been a dreaded complication of liver transplantation, and the accompanying transfusion is associated with adverse outcomes in the form of decreased patient and graft survival. With advances in both surgical techniques and anesthetic management during transplantation, blood and blood products requirements reduced significantly. However, transfusion practices vary among different centers. The altered coagulation parameters in patients with liver cirrhosis results in a state of “rebalanced hemostasis” and patients are just as likely to clot as they are to bleed. Commonly used coagulation tests do not always reflect this new state and can, therefore, be misleading. Transfusion of blood products solely to correct abnormal parameters may worsen the coagulation status, thus adversely affecting patient outcome. Point-of-care tests such as thromboelastometry more reliably predict the risk of bleeding in these patients and in addition may provide quicker turnaround times compared to routine tests. Perioperative management should also include the possibility of thrombosis in these patients, and the use of low-molecular-weight heparin correlates with better patient survival. This review article aims to highlight the concept of rebalanced hemostasis, limitation of routine coagulation tests, and harmful effect of empiric transfusion of blood products.

Reproducibility of TEG Parameters in Stable Cirrhotics

Background

Thromboelastography (TEG) has become the standard of care in liver-transplant surgery to identify real-time abnormalities in the coagulation cascade. To our knowledge, no studies have been performed to measure the intrasubject reproducibility of TEG parameters in cirrhotic patients.

Objective

To perform a validation study to determine the reproducibility of TEG in cirrhosis.

Methods

We recruited 30 patients with stable cirrhosis and tested 25 of them. Two blood specimens were drawn 1 hour apart; we measured the TEG parameters R time, K time, angle, maximum amplitude (MA), and functional fibrinogen (FF), along with conventional coagulation parameters. Reproducibility was assessed using the intraclass coefficient test. The TEG parameters were then compared with conventional coagulation test results.

Results

The K time, angle, MA, and FF results showed excellent reproducibility (r > 0.7; P <.001). Platelets and fibrinogen correlated with MA and K time; prothrombin time (PT) and activated partial thromboplastin time (aPTT) were inversely correlated with MA.

Conclusion

All parameters were reproducible when measured 1 hour apart. TEG may be suitable to investigate coagulation characteristics in patients with clinically stable cirrhosis; however, further studies are needed in patients with more advanced cirrhosis, in whomblood product use may be more prevalent.

K time & maximum amplitude of thromboelastogram predict post-central venous cannulation bleeding in patients with cirrhosis: A pilot study

Background & objectives:

Coagulation and haemostasis are dynamic processes. The haemostatic changes in liver disease affect all aspects of coagulation. The prothrombin time (PT)/international normalized ratio (INR) was developed to monitor oral anticoagulant therapy and the activated partial thromboplastin time to investigate inheritable single factor deficiencies. Viscoelastic tests such as thromboelastogram (TEG) give information about dynamics of clot formation (coagulation factor and anticoagulant activity), clot strength (platelets and fibrinogen) and clot stability (finbrinolysis and factor XIII). Administration of blood products before invasive procedures is still guided by INR and platelet count in patients of liver disease. This study was aimed to evaluate the validity of TEG to predict post-procedural bleed after central venous cannulation in patients with cirrhosis.

Methods:

Ninety patients aged 20-70 yr diagnosed with liver cirrhosis requiring elective central venous catheter (CVC) insertion were studied. Platelet count, INR, serum creatinine, TEG and Child-Turcotte-Pugh (CTP) score were recorded before the procedure. Right-sided internal jugular vein was cannulated. On the basis of presence or absence of post-procedural bleed, patients were divided into bleeding and non-bleeding groups. The CTP score, component of TEG (R - reaction time, K - coagulation time, MA - maximum amplitude and α - angle) and laboratory parameters of both the groups were compared.

Results:

Bleeding was seen more when CTP scores were ≥10 (P=0.05). The K time of 3.05 min or more on thromboelastograph was a significant predictor of bleeding [area under the curve (AUC) 0.694, P=0.047]. MA of 48.8 mm or more was a significant predictor of non-bleeding. INR ≥2.6 was a significant predictor of bleeding (AUC 0.765, P=0.005). K time had a low-positive predictive value of 20 per cent and the positive and negative likelihood ratios of 1.87 and 0.48, respectively.

Interpretation & conclusions:

Our results show that the cut-off value for INR ≥2.6 and K time ≥3.05 min predict bleeding and MA ≥48.8 mm predicts non-bleeding in patients with cirrhosis undergoing central venous pressure catheter cannulation.

Correction of Severe Coagulopathy and Hyperfibrinolysis by Tranexamic Acid and Recombinant Factor VIIa in a Cirrhotic Patient After Trauma: A Case Report

Coagulopathy induced by trauma or cirrhosis is a well-recognized entity. Viscoelastic testing has been used in either condition for goal-directed transfusion and detection of fibrinolysis since conventional coagulation tests do not correlate with clinical risk of bleeding. Hemostatic resuscitation may not be adequate for a trauma patient with liver disease due to complex alterations in coagulation systems and occasionally require adjuvant therapy. We report a case of trauma-induced coagulopathy presenting as severe hyperfibrinolysis in a cirrhotic patient who was refractory to hemostatic resuscitation but was rapidly corrected by the administration of tranexamic acid and recombinant Factor VIIa.

A nationwide analysis of re-exploration after liver transplant

BACKGROUND

A retrospective review to investigate rate and outcomes of re-exploration following liver transplantation in the United States.

METHODS

The NIS database was used to examine outcomes of patients who underwent re-exploration following liver transplantation from 2002 to 2012. Multivariate regression analysis was performed to compare outcomes of patients with and without reoperation.

RESULTS

We sampled a total of 12,075 patients who underwent liver transplantation. Of these, 1505 (12.5%) had re-exploration during the same hospitalization. Hemorrhagic (67.9%) and biliary tract anastomosis complication (14.8%) were the most common reasons for reoperation. Patients with reoperation had a significantly higher mortality than those who did not (11.6% vs. 3.8%, AOR: 3.01, P < 0.01). Preoperative coagulopathy (AOR: 1.71, P < 0.01) and renal failure (AOR: 1.57, P < 0.01) were associated with hemorrhagic complications. Peripheral vascular disorders (AOR: 2.15, P < 0.01) and coagulopathy (AOR: 1.32, P < 0.01) were significantly associated with vascular complications. Risk of wound disruption was significantly higher in patients with chronic pulmonary disease (AOR: 1.50, P < 0.01).

CONCLUSION

Re-exploration after liver transplantation is relatively common (12.5%), with hemorrhagic complication as the most common reason for reoperation. Preoperative coagulation disorders significantly increase hemorrhagic and vascular complications. Further clinical trails should investigate prophylactic strategies in high risk patients to prevent unplanned reoperation.

Arterial injury during transcatheter arterial chemoembolization for hepatocellular carcinoma: predictors of risk and outcome

PURPOSE

To investigate clinical features and results of follow-up in patients with arterial injury during transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma.

METHODS

From 2005 to 2015, 2219 TACE procedures were performed in 906 patients in our hospital. Iatrogenic arterial injury occurred during 38 TACE procedures (sessions) in 35 patients (24 men, 11 women; mean age 71.8 years). The incidence of arterial injury was 1.7%. We evaluated the characteristics of arterial injury, and evaluated the risk factors for incomplete recanalization of the injured artery at follow-up angiography conducted after 1-11 months (mean 102.5 days).

RESULTS

Iatrogenic arterial injury was caused by the microcatheter in 34 of 38 cases (86.8%). There were 15 cases (39.5%) in which the replaced hepatic artery or the extrahepatic artery was the parasitic supply. Extravasation occurred in five cases. In 36 of 38 cases, follow-up angiography was performed. We divided 36 cases into two groups: complete reopening (n = 24) and non-complete reopening (n = 12). The two groups were compared regarding the factors associated with incomplete recanalization of the injured artery at follow-up. Injury length >3 cm (p = 0.0002) and proximal arterial injury (proximal to the segmental artery; p = 0.03) were significant risk factors for non-complete reopening of the injured artery.

CONCLUSION

Iatrogenic arterial injury frequently occurred in the extrahepatic artery or replaced hepatic artery. Recanalization rate of arterial injury was high; however, injury length >3 cm and proximal arterial injury were risk factors for non-complete reopening of the injured artery.

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.

Impaired Platelet Aggregation and Rebalanced Hemostasis in Patients with Chronic Hepatitis C Virus Infection

Increased risk of both cardiovascular disease (CVD) and bleeding has been found in patients with chronic hepatitis C (CHC) infection, and a re-balanced hemostasis has been proposed. The aim of this study was to investigate functional whole blood coagulation and platelet function in CHC infection. The prospective study included 82 patients with CHC infection (39 with advanced liver fibrosis and 43 with no or mild liver fibrosis) and 39 healthy controls. A total of 33 patients were treated for CHC infection and achieved sustained virological response (SVR). Baseline and post-treatment blood samples were collected. Hemostasis was assessed by both standard coagulation tests and functional whole blood hemostatic assays (thromboelastograhy (TEG), and platelet aggregation (Multiplate). Patients with CHC and advanced fibrosis had impaired platelet aggregation both compared to patients with no or mild fibrosis and to healthy controls. Patients with CHC and advanced fibrosis also had lower antithrombin, platelet count, and coagulation factors II-VII-X compared to healthy controls. In contrast, TEG did not differ between groups. In treated patients achieving SVR, post-treatment platelet count was higher than pre-treatment counts (p = 0.033) and ADPtest, ASPItest, and RISTOhightest all increased post treatment (all p < 0.05). All Multiplate tests values, however, remained below those in the healthy controls. CHC-infected patients displayed evidence of rebalanced hemostasis with only partly hemostatic normalization in patients achieving SVR. The implications of rebalanced hemostasis and especially the impact on risk of CVD and bleeding warrants further studies.

Anaesthesia for liver transplantation

Liver transplantation is a complex procedure that requires a truly multidisciplinary team approach with anaesthetic involvement from the outset in order to ensure excellent outcomes. Before a patient is placed on the waiting list for a liver transplant, a thorough evaluation is undertaken and his/her suitability for transplantation discussed in a patient selection committee meeting. The perioperative management of patients requiring transplantation can be challenging because of the systemic implications of liver disease, approaches to surgical technique and the quality of the grafts used; an increase in the use of marginal donor organs to meet the organ demand poses its own unique difficulties.

Flow, Liver, Flow: A Retrospective Analysis of the Interplay of Liver Disease and Coagulopathy in Chronic Subdural Hematoma

BACKGROUND

Chronic subdural hematoma (cSDH) is a common neurosurgical ailment, particularly in elderly patients. A recent study uncovered an association between liver disease and recurrence in patients with cSDH. Here, we explored that relationship to identify recurrence predictors in at-risk patients.

OBJECTIVE

We hypothesized that the association between liver disease and recurrence was attributable to coagulopathy secondary to liver disease.

METHODS

We retrospectively reviewed all patients with cSDH treated with burr-hole drainage by 2 surgeons between 2007 and 2015. Comorbidities and laboratory findings for each patient were examined by Pearson χ² analysis or Mann-Whitney U tests.

RESULTS

We identified 261 cSDH in 215 patients. Patients were a mean age of 65.6 years, and 72% were male. Sixteen patients with cSDH required repeat surgery (6.1%). There were 123 coagulopathic patients (47.1%), and 14 with liver disease (5.4%), all of whom were coagulopathic (P < 0.001). Coagulopathic patients with liver disease were more likely to experience recurrence than patients with coagulopathy alone (relative risk = 4.09, P = 0.019). Patients with liver disease had significantly elevated prothrombin time (P = 0.013) and reduced platelet counts (P < 0.001). Platelets also were reduced in coagulopathic patients with liver disease, as compared with those with coagulopathy alone (P = 0.002). Thrombocytopenia remained significant in a multivariate analysis (P < 0.001).

CONCLUSIONS

Liver disease is significantly associated with the recurrence of cSDH. Although coagulopathy alone does not predict recurrence, patients with coagulopathy and liver disease are at greater risk for recurrence than those with coagulopathy alone. Liver disease effects are reflected in certain hematologic laboratory values.

Haematology and coagulation profiles in cats with congenital portosystemic shunts

Objectives

The objectives of this study were, first, to report the haematological parameters and coagulation times for cats with a congenital portosystemic shunt (CPSS) and the influence of surgical shunt attenuation on these parameters; and, second, to identify any association between prolongation in coagulation profiles and incidence of perioperative haemorrhage.

Methods

This was a retrospective clinical study using client-owned cats with a CPSS. Signalment, shunt type (extra- or intrahepatic), degree of shunt attenuation (complete or partial), haematological parameters, prothrombin time (PT) and activated partial thromboplastin time (aPTT) test results, and occurrence of any perioperative clinical bleeding complications were recorded for cats undergoing surgical treatment of a CPSS at the Royal Veterinary College, UK, between 1994 and 2011.

Results

Forty-two cats were included. Thirty-six (85.7%) had an extrahepatic CPSS and six (14.3%) had an intrahepatic CPSS. Preoperatively, mean cell volume (MCV) and mean cell haemoglobin (MCH) were below the reference interval (RI) in 32 (76.2%) and 31 (73.8%) cats, respectively. Red blood cell count and mean cell haemoglobin concentration (MCHC) were above the RI in 10 (23.8%) and eight (19.1%) cats, respectively. Postoperatively, there were significant increases in haematocrit ( P = 0.044), MCV ( P = 0.008) and MCH ( P = 0.002). Despite the significant increase in MCV postoperatively, the median MCV postoperatively was below the RI, indicating persistence of microcytosis. Preoperatively, PT was above the upper RI in 14 cats (87.5%), and aPTT was above the upper RI in 11 cats (68.8%). No cat demonstrated a perioperative clinical bleeding complication.

Conclusions and relevance

Cats with a CPSS are likely to present with a microcytosis, but rarely present with anaemia, leukocytosis or thrombocytopenia. Surgical attenuation of the CPSS results in a significant increase in the HCT and MCV. Coagulation profiles in cats with a CPSS are likely to be prolonged, irrespective of shunt type, but do not appear to be associated with an increased risk of clinical bleeding.

A conceptual and practical approach to haemostasis in paediatric liver disease

Children with liver disease can develop severe bleeding episodes and thrombosis. Liver failure usually results in decreased levels of procoagulant and anticoagulant factors. Additional risk factors, including changes in vascular flow and endothelial function, are of importance for the development of bleeding or thrombosis in individual vascular beds. Detailed studies of haemostatic disturbances in the setting of paediatric liver disease are sparse and extrapolation from adult studies is common. The spectrum of liver diseases and the haemostatic system differs between children and adults. Specific paediatric liver diseases are reported to have more distinctive effects on haemostasis and the risk of bleeding and/or thrombosis.

CONCLUSION

we propose a model regarding haemostasis in paediatric liver disease, taking into account a number of specific variables and mechanisms, as well as the type of liver disease, which will provide a framework for clinical decision-making in these complex patients.

The utility of thromboelastography in inherited and acquired bleeding disorders

Thromboelastography (TEG) was first described by Hartert in 1948, and was designed to monitor viscoelastic clot strength in whole blood in real time. The current TEG method and Rotational Thromboelastometry (ROTEM) were subsequently developed from the original principles. Both of the modern methods provide data by measuring changes in the viscoelastic strength of a small sample of clotting blood in response to a constant rotational force. The important advantage of these techniques is to visually observe and quantify blood coagulation including the propagation, stabilization and dissolution phases of clot formation under low shear conditions. Analysis of the results provides detailed kinetic data on fibrin generation, clot strength and fibrinolysis. These TEG/ROTEM analyses therefore enable evaluation of global clotting function and the monitoring of haemostatic treatment in various clinical situations, not only in patients with genetic bleeding disorders, such as haemophilia, but also in patients undergoing cardiac surgery, liver transplantation or suffering from traumatic injury. Some evidence suggests that haemostatic management using TEG/ROTEM leads to a reduction in total transfusions of whole blood or clotting factors. Wider clinical application of this technology seems likely.

[Anesthesia with liver failure]

Liver failure can be categorized into acute liver failure, chronic liver failure and acute decompensation of chronic liver failure, the so-called acute-on-chronic liver failure, the incidence of which has increased over the last few years. Liver failure leads to a variety of pathophysiological changes where the extent is dependent on the nature and duration of the liver disease. This includes restriction of synthesis and metabolism, such as coagulation defects. Especially chronic liver failure is associated with malfunction of extrahepatic organs, such as the cardiovascular system, the respiratory system and the kidneys. In addition to these pathophysiological alterations the Child-Turcotte-Pugh classification (CTP) and the model of end stage liver disease (MELD) are used for perioperative risk stratification.

Reducing transfusion requirements in liver transplantation

Liver transplantation (LT) was historically associated with massive blood loss and transfusion. Over the past two decades transfusion requirements have reduced dramatically and increasingly transfusion-free transplantation is a reality. Both bleeding and transfusion are associated with adverse outcomes in LT. Minimising bleeding and reducing unnecessary transfusions are therefore key goals in the perioperative period. As the understanding of the causes of bleeding has evolved so too have techniques to minimize or reduce the impact of blood loss. Surgical “piggyback” techniques, anaesthetic low central venous pressure and haemodilution strategies and the use of autologous cell salvage, point of care monitoring and targeted correction of coagulopathy, particularly through use of factor concentrates, have all contributed to declining reliance on allogenic blood products. Pre-emptive management of preoperative anaemia and adoption of more restrictive transfusion thresholds is increasingly common as patient blood management (PBM) gains momentum. Despite progress, increasing use of marginal grafts and transplantation of sicker recipients will continue to present new challenges in bleeding and transfusion management. Variation in practice across different centres and within the literature demonstrates the current lack of clear transfusion guidance. In this article we summarise the causes and predictors of bleeding and present the evidence for a variety of PBM strategies in LT.