Argatroban therapy in heparin-induced thrombocytopenia with hepatic dysfunction

Anticoagulation Management during Extracorporeal Membrane Oxygenation-A Mini-Review

Extracorporeal membrane oxygenation (ECMO) has been established as a life-saving technique for patients with the most severe forms of respiratory or cardiac failure. It can, however, be associated with severe complications. Anticoagulation therapy is required to prevent ECMO circuit thrombosis. It is, however, associated with an increased risk of hemocoagulation disorders. Thus, safe anticoagulation is a cornerstone of ECMO therapy. The most frequently used anticoagulant is unfractionated heparin, which can, however, cause significant adverse effects. Novel drugs (e.g., argatroban and bivalirudin) may be superior to heparin in the better predictability of their effects, functioning independently of antithrombin, inhibiting thrombin bound to fibrin, and eliminating heparin-induced thrombocytopenia. It is also necessary to keep in mind that hemocoagulation tests are not specific, and their results, used for setting up the dosage, can be biased by many factors. The knowledge of the advantages and disadvantages of particular drugs, limitations of particular tests, and individualization are cornerstones of prevention against critical events, such as life-threatening bleeding or acute oxygenator failure followed by life-threatening hypoxemia and hemodynamic deterioration. This paper describes the effects of anticoagulant drugs used in ECMO and their monitoring, highlighting specific conditions and factors that might influence coagulation and anticoagulation measurements.

Use of the CytoSorb® filter for elimination of residual therapeutic argatroban concentrations during heparinized cardiopulmonary bypass for heart transplantation

INTRODUCTION

No antidote or established extracorporeal elimination strategy is available for argatroban. Hemadsorption facilitates elimination of smaller drugs.

CASE REPORT

A 34-year-old patient underwent urgent heart transplantation. Because of a history of heparin-induced thrombocytopenia, preoperative anticoagulation was performed with argatroban. Despite ceasing of the continuous infusion of argatroban 2 h before surgery, concentration only declined from 0.60 μg/ml to 0.58 μg/ml before surgery, and the activated clotting time (ACT) value shortly was 223 s. Microvascular bleeding had been observed when starting surgery. A CytoSorb® absorption column was integrated into the system of the heparin-anticoagulated cardiopulmonary bypass (CPB) circuit and a flow of 400 mL/min provided during the 2 h of extracorporeal circulation. The argatroban concentration after weaning from CPB was 0.04 μg/ml and satisfying hemostasis had been achieved after protamine administration.

CONCLUSION

Data indicate that the CytoSorb® absorption column might be an effective tool for quick extracorporeal removal of therapeutic concentrations of argatroban.

Anticoagulation Considerations in Liver Disease

Coagulopathy of liver disease is a complex pathology that may result in thrombosis and/or bleeding complications. Routine laboratory values are not always reflective of the degree of these risks. Additionally, prophylaxis and treatment of venous thromboembolism in patients with cirrhosis require careful evaluation when selecting and monitoring drug therapy for these indications. Therefore, this article aims to provide insight regarding coagulopathy of liver disease, influence on laboratory values, and anticoagulant therapy considerations for critical care nurses assuming care for patients with cirrhosis.

Prediction of adverse drug reactions based on knowledge graph embedding

BACKGROUND

Adverse drug reactions (ADRs) are an important concern in the medication process and can pose a substantial economic burden for patients and hospitals. Because of the limitations of clinical trials, it is difficult to identify all possible ADRs of a drug before it is marketed. We developed a new model based on data mining technology to predict potential ADRs based on available drug data.

METHOD

Based on the Word2Vec model in Nature Language Processing, we propose a new knowledge graph embedding method that embeds drugs and ADRs into their respective vectors and builds a logistic regression classification model to predict whether a given drug will have ADRs.

RESULT

First, a new knowledge graph embedding method was proposed, and comparison with similar studies showed that our model not only had high prediction accuracy but also was simpler in model structure. In our experiments, the AUC of the classification model reached a maximum of 0.87, and the mean AUC was 0.863.

CONCLUSION

In this paper, we introduce a new method to embed knowledge graph to vectorize drugs and ADRs, then use a logistic regression classification model to predict whether there is a causal relationship between them. The experiment showed that the use of knowledge graph embedding can effectively encode drugs and ADRs. And the proposed ADRs prediction system is also very effective.

Bivalirudin fails to prevent atrial thrombus development in heparin-induced thrombocytopaenia and thrombosis syndrome

An 81-year-old woman presented with acute decompensated heart failure due to new-onset atrial fibrillation and a flail myxomatous mitral valve which necessitated surgical mitral valve repair. No atrial thrombi were noted on transoesophageal echocardiograms performed prior to surgery and intraoperatively. Immediately postoperatively, while treated with unfractionated heparin, the patient developed thrombocytopaenia with positive platelet factor 4 antibodies and an abnormal serotonin functional platelet assay, consistent with heparin-induced thrombocytopaenia. The anticoagulation therapy was changed to the direct thrombin inhibitor bivalirudin with an improvement in the platelet count. Despite bivalirudin therapy, a left atrial layering thrombus was revealed on transoesophageal echocardiogram performed in preparation for cardioversion of the symptomatic atrial fibrillation. Anticoagulation was changed to warfarin, and the patient was discharged without thromboembolic complications neither during her hospital stay nor the 3-year outpatient follow-up.

Argatroban pharmacokinetics and pharmacodynamics in critically ill cardiac surgical patients with suspected heparin-induced thrombocytopenia

Only limited data are available on the pharmacokinetic and pharmacodynamic properties of argatroban in critically ill patients under clinical conditions. We determined plasma concentrations of argatroban, and its main metabolite M1, within a time period of 48 hours in 25 critically ill cardiac surgical patients, who were suspected of heparininduced thrombocytopenia and had the clinical need for anticoagulation. Argatroban infusion was started at 0.5 µg/kg/minute, and adjusted in 0.1–0.25 µg/kg/minute increments when the activated partial thromboplastin time (aPTT) was not within the target range. Median argatroban plasma half-life was 2.7 hours (interquartile range 1.8 to 7.3). Linear regression analysis revealed that argatroban half-life was significantly related to the total bilirubin concentration (R2 = 0.66, p< 0.001), as well as to the metabolism of argatroban, which was assessed by the ratio of the areas under the concentration time curves (AUC) of argatroban and M1 (R2 = 0.60, p< 0.001). Continuous veno-venous haemodialysis did not significantly affect argatroban plasma half-life. The predictive property of argatroban plasma levels for aPTT was low (R2 = 0.28, p< 0.001). Multiple linear regression analysis revealed significant contributions of age and serum albumin levels to the effect of argatroban on aPTT, expressed as the AUC ratio argatroban/aPTT (R2 = 0.67, adjusted R2 = 0.65, p< 0.001). In conclusion, argatroban plasma half-life is markedly increased in critically ill cardiac surgical patients, and further prolonged by hepatic dysfunction due to impaired metabolism. Patient age and serum albumin concentration significantly contribute to the variability in the anticoagulant activity of argatroban.

Early initiation of argatroban therapy in the management of acute superior mesenteric venous thrombosis

Acute superior mesenteric venous thrombosis (ASMVT) is an intractable disease with poor prognosis. Argatroban, a direct thrombin inhibitor, may be a novel anticoagulant method in the therapy of ASMVT. The aim of the present study was to assess the efficacy and safety of early argatroban therapy in ASMVT patients. The current retrospective study reviewed a consecutive series of ASMVT patients receiving early argatroban therapy during hospitalization between March 2013 and April 2014, with 18 ASMVT patients included in the study. Of these, 16 patients without hepatic dysfunction underwent anticoagulant therapy with argatroban with a mean dose of 1.57±0.34 µg/kg/min and a mean duration of 12.2±3.7 days, while their activated partial thromboplastin time (aPTT) was elevated to 1.95±0.26 times the baseline value. In addition, 2 hepatic dysfunction patients received therapy with a dose of 0.41 µg/kg/min and 0.46 µg/kg/min, and with aPTT of 1.68 and 1.62 times the baseline value, respectively. Overall, 94% (n=17) of the patients presented clinical improvement, while 88% (n=16) of patients presented partially or completely dissolved thrombus in contrast-enhanced computed tomography images. The incidence of surgery and bowel resection was 6% (excluding 1 case with intestinal necrosis detected on admission). Furthermore, 11% (n=2) of patients experienced a bleeding episode, however no major bleeding or mortality occurred during hospitalization. During the follow-up, the mortality and the recurrence rate were 6% and 11%, respectively. In conclusion, early initiation of argatroban treatment may be an effective and safe therapy in ASMVT, manifesting efficient resolution of the thrombus, rapid improvement of symptoms, low incidence of bowel resection and bleeding complication, and low mortality rate.

Pharmacotherapy of heparin-induced thrombocytopenia: therapeutic options and challenges in the clinical practices

Heparin-induced thrombocytopenia (HIT) is an immune response to heparin associated with significant morbidity and mortality in hospitalized patients if unidentified as soon as possible, owing to thromboembolic complications involving both arterial and venous systems. Early diagnoses based on a comprehensive interpretation of clinical and laboratory information improves clinical outcomes. Management principles of strongly suspected HIT should not be delayed for laboratory result confirmation. Treatment strategies have been introduced including new, safe, and effective agents. This review summarizes the clinical therapeutic options for HIT addressing the use of parenteral direct thrombin inhibitors and indirect factor Xa inhibitors as well as the potential non-vitamin K antagonist oral anticoagulants.

How we manage patients with heparin induced thrombocytopenia

Heparin induced thrombocytopenia (HIT) remains a rare, but significant, condition related to mortality and morbidity. The incidence has decreased with reduced use of unfractionated heparin, with the exception of cardiac surgery. Due to the high risk of thrombosis, a switch to a non-heparin anticoagulant is required, until platelet counts normalize. Within the acute setting, argatroban, fondaparinux and direct acting oral anticoagulants (DOACS) are therapeutic options. In patients with HIT-associated thrombosis or who require long-term anticoagulation, warfarin remains the preference, but DOACs are attractive alternatives.

[Argatroban, a new antithrombotic treatment for heparin-induced thrombocytopenia application in cardiac surgery and in intensive care]

OBJECTIVES

Although heparin-induced thrombocytopemia (HIT) is uncommon, its thromboembolic complications are potentially life-threatening. The low-molecular weight heparins are less responsible of HIT than unfractionated heparin (UFH) but this latter is still indicated in some circumstances such as cardiac surgery. Argatroban, a selective thrombin inhibitor, recently available, has been indicated in HIT treatment. This review presents the main pharmacological characteristics, its indications and uses in the context of cardiac surgery and in intensive care medicine.

METHODS

Review of the literature in Medline database over the past 15 years using the following keywords: argatroban, cardiac surgery, circulatory assistance, cardiopulmonary bypass.

RESULTS

Despite its short-acting pharmacokinetic, argatroban cannot be recommended during cardiopulmonary bypass. On the contrary, argatroban is indicated in many circumstances in postoperative period of various cardiac surgeries (on-pump, off-pump, circulatory assistance). Nevertheless, after cardiac surgery, doses have to be adapted according to coagulation laboratory testing (ACT), particularly in patients presenting acute organ failure (kidney injury, heart failure, liver failure). This compound has no antagonist and is excluded during severe hepatic failure. The continuous intravenous administration is a drawback.

CONCLUSION

Argatroban is a new direct competitive thrombin inhibitor well evaluated as treatment of HIT after cardiac surgery. In HIT management, argatroban is an interesting alternative to lepirudin that is not anymore available and danaparoid because of supply disturbances.

Update on argatroban for the prophylaxis and treatment of heparin-induced thrombocytopenia type II

Heparin-induced thrombocytopenia (HIT) is a rare but potentially severe complication of heparin therapy that is strongly associated with venous and arterial thrombosis (HIT and thrombosis syndrome, HITTS), which requires urgent detection and treatment with a nonheparin anticoagulant. Argatroban, a synthetic direct thrombin inhibitor, is indicated for the treatment and prophylaxis of thrombosis in patients with HIT, including those undergoing percutaneous coronary intervention. Argatroban has a relatively short elimination half-life of approximately 45 minutes, which is predominantly performed via hepatic metabolism. It is derived from L-arginine that selectively and reversibly inhibits thrombin, both clot-bound and free, at the catalytic site. Argatroban anticoagulation has been systematically studied in patients with HIT and HITTS and proved to be a safe and effective agent for this indication. The current review presents the pharmacology of argatroban, data regarding monitoring of the agent, and an overview of the results of the major clinical trials assessing argatroban anticoagulation in HIT patients. Additionally, data from recent clinical trials with argatroban use in more special indications such as in percutaneous coronary intervention, liver dysfunction, renal replacement therapy, and intensive care medicine, are reviewed. The approved initial dosage of argatroban for adults with HIT or HITTS is 2 μg/kg/minute for patients with normal hepatic function and 0.5 μg/kg/minute for patients with hepatic dysfunction. There is evidence that a reduced initial dose may also be advisable for patients with heart failure, multiple organ dysfunction, severe anasarca, or after cardiac surgery. Given this information, argatroban can be effectively used in treating HIT with monitoring of activated partial thromboplastin time.

Argatroban therapy in heparin-induced thrombocytopenia

Argatroban is a direct thrombin inhibitor approved for anticoagulation in heparin-induced thrombocytopenia (HIT; in several countries) and in patients with or at risk of HIT undergoing percutaneous coronary intervention (PCI; in the USA). HIT is a relatively common extreme prothrombotic condition. When HIT is reasonably suspected, an alternative anticoagulant should be promptly initiated. In historical controlled studies, argatroban reduced new thrombosis, mortality from thrombosis and the composite of death, amputation or thrombosis, without increasing bleeding. With intravenous infusion, advantages include short half-life, easy monitoring and elimination primarily by hepatobiliary (rather than renal) means. In patients undergoing PCI, argatroban with or without glycoprotein IIb/IIIa inhibition leads to high rates of procedural success with low bleeding risk. Herein we review argatroban therapy for HIT and for PCI.

Non-recovery of ACT in a patient with heparin-induced thrombocytopenia type II during mitral valve replacement using argatroban anticoagulation

Argatroban was used as the anticoagulant during cardiopulmonary bypass (CPB) in a patient with heparin-induced thrombocytopenia (HIT) type II undergoing mitral valve replacement. Dosage was reduced because of preoperative congestive liver disorder. Perioperative coagulability was poor, and, ultimately, failure of hemostasis led to a fatal outcome. Although argatroban use as an anticoagulant for HIT is reported, the optimal dose has not been established. During long-term CPB, increasing the total dosage may extend anticoagulant ability, leading to dose dependence. Because no antagonist for argatroban exists, failure of hemostasis might occur.

Heparin-induced thrombocytopenia associated with acute liver graft failure

An orthotopic liver transplantation (OLT) is of a proven benefit in an acute liver failure (ALF). Heparin-induced thrombocytopenia (HIT) is strongly associated with thromboembolic complications. We present the case of a 56-year-old patient who underwent an OLT owing to an ALF of unknown aetiology. HIT type II with consecutive hepatic and portal vein thrombosis caused progressive graft failure. Total hepatectomy and porto-caval shunt were performed to reduce the toxic effects of liver cell necrosis such as multiorgan failure involving the respiratory, renal and cardiovascular systems. A suitable liver graft was allocated after an anhepatic bridging period of 56 h. Specific complications due to end-stage liver failure-such as acidosis, coagulopathy, decrease of vascular resistance, cerebral oedema, myocardial infarction and right heart failure-were treated. Following a re-OLT, the patient made a complete recovery. We present a rare case of HIT-associated early liver graft failure followed by a prolonged anhepatic phase and finally a successful re-OLT.

Argatroban dose reductions for suspected heparin-induced thrombocytopenia complicated by child-pugh class C liver disease

OBJECTIVE

To report our experience of reduced-dose argatroban in a patient with suspected heparin-induced thrombocytopenia (HIT) and Child-Pugh class C liver disease and review the relevant literature to summarize current recommendations on argatroban use in patients with severe liver disease.

CASE SUMMARY

A 58-year-old male with Child-Pugh class C liver disease (Model for End-Stage Liver Disease [MELD] score = 31, total bilirubin 4.5 mg/dL) and hemodialysis-dependent renal failure was hospitalized with acute deep vein thrombosis (DVT). Three days after heparin initiation for DVT, he developed thrombocytopenia. Given his heparin exposure (both for treatment of DVT and ongoing hemodialysis), HIT was suspected and all heparinoids were immediately discontinued. Argatroban was initiated for the treatment of HIT while laboratory testing for HIT antibodies and the serotonin release assay were completed. Because of the patient's advanced liver disease, the starting dose of argatroban was reduced to 0.2 μg/kg/min, with frequent monitoring of the activated partial thromboplastin time (aPTT) (goal 60-85 seconds). Despite this dose reduction, the aPTT was supratherapeutic. Following further dose reductions, a final argatroban maintenance dose of 0.05 μg/kg/min was necessary for the attainment of goal aPTTs.

DISCUSSION

Reducing the starting dose of argatroban to 0.5 μg/kg/min is recommended in patients with liver disease. Nevertheless, this recommended dose is largely based on data from patients with more moderate liver disease (eg, Child-Pugh class A or B), and dosing in more advanced liver disease remains largely unexplored. Patients with more advanced liver disease may require additional dose reductions to avoid supratherapeutic concentrations of anticoagulation agents and to minimize bleeding risk.

CONCLUSIONS

This report illustrates the importance of careful selection of argatroban dosing and appropriate aPTT monitoring in patients with severe liver disease. Excessive anticoagulation may precipitate major bleeding complications, placing patients with this complicated disease at undue risk.

Efficacy of a Nurse-Managed Argatroban Dose-Adjustment Protocol in a University Teaching Hospital

Background

Argatroban is a direct thrombin inhibitor used in the treatment of heparin-induced thrombocytopenia (HIT). No study has evaluated the safety and efficacy of a nurse-managed argatroban dosing protocol.

Methods

We performed a retrospective analysis of 151 total admissions (129 patients) in which argatroban infusions were administered before and after protocol implementation. The preprotocol and postprotocol groups consisted of 69 and 68 admissions, respectively. Patients were eligible for inclusion if they were ≥18 years old and received an argatroban drip for any reason in the 2 years prior to or following protocol implementation.

Results

There were no statistically significant differences in the incidence of clinically overt bleeding (primary study safety endpoint) between groups. There was no difference between groups in the primary efficacy endpoints, the mean number of partial thromboplastin time (aPTT) assessments per day, and dose adjustments. The mean number of sub- and supratherapeutic aPTTs during treatment was higher in the preprotocol group when utilizing the specified range in the preprotocol group and the protocol's aPTT range (45–90 s); the preprotocol and postprotocol groups had an average of 3.4 and 1.04 subtherapeutic aPTTs, respectively ( P = .008). Similarly, the preprotocol group had an average of 4.98 supratherapeutic aPTTs, while the postprotocol group had 1.84 ( P < .001). There was no difference in duration of argatroban infusion in the preprotocol group compared to the postprotocol group with regard to duration of infusion or final infusion rate.

Conclusions

This nurse-managed argatroban adjustment protocol provides similar safety and efficacy outcomes and decreased monitoring when pre and post implementation were compared.

Safety and Efficacy of Argatroban in the Management of Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a life-threatening adverse reaction to heparin therapy that is characterized by thrombocytopenia and an increased risk of venous and arterial thrombosis. According to guidelines, in patients with strongly suspected or confirmed HIT all sources of heparin have to be discontinued and an alternative, nonheparin anticoagulant for HIT treatment must immediately be started. For both the prophylaxis of thrombembolic events in HIT and the treatment of HIT with thrombosis the direct thrombin inhibitor argatroban is approved in the United States. The objective of this review is to describe the mechanism of action and the pharmacokinetic profile of argatroban, to characterize argatroban regarding its safety and therapeutic efficacy and to discuss its place in therapy in HIT.

Thrombocytopenia following percutaneous coronary intervention

BACKGROUND

Thrombocytopenia following percutaneous coronary intervention (PCI) is an underappreciated condition that is often clinically challenging. There are no guidelines on the management of patients with this condition.

OBJECTIVE

To review recent data in etiologies, risk factors, prevention, management, and prognostic implications of thrombocytopenia following PCI.

EVIDENCE ACQUISITION

Search of MEDLINE, EMBASE, the Cochrane Database, and Google Scholar using the term thrombocytopenia + PCI and other relevant keywords to identify systematic reviews, clinical trials, cohort studies, case series, and case reports. The review was limited to English-language articles published between January 1980 and June 2009. Articles on patients with baseline thrombocytopenia prior to PCI were excluded.

EVIDENCE SYNTHESIS

Thrombocytopenia is not infrequent following PCI. The typical patient with post-PCI thrombocytopenia is on multiple therapies that can potentially cause a decrease in the platelet count. Identification of the cause is critical because management of the condition varies significantly based on the etiology. The severity of the thrombocytopenia also determines the clinical management of the patient. Several observational studies have demonstrated the adverse prognostic impact of the complication on clinical outcomes and have identified risk factors.

CONCLUSIONS

Judicious use of therapies that can cause thrombocytopenia, efficient detection of the cause of the decrease in platelet count, and appropriate management of the condition can potentially improve the quality of care and outcomes following PCI. Further research into risk factors that predispose post-PCI patients to developing thrombocytopenia is warranted.

Pharmacology of argatroban

Argatroban is a synthetic, small-molecule direct thrombin inhibitor that is approved in the USA, the EU and Japan for prophylaxis or treatment of thrombosis in patients with heparin-induced thrombocytopenia (HIT), and for anticoagulation of HIT patients undergoing PCI. Argatroban binds reversibly to, and inhibits both soluble and clot-bound thrombin. Argatroban does not generate antibodies, is not susceptible to degradation by proteases and is cleared hepatically. It has a predictable anticoagulant effect and there is a good correlation between dose, plasma concentration and pharmacodynamic effect. Initial clinical studies suggest that further investigations to establish the use of argatroban in ischemic stroke, acute coronary syndrome, hemodialysis, blood oxygenation, off-pump cardiac surgery and other clinical indications are warranted.

Monitoring of the anticoagulants argatroban and lepirudin: a comparison of laboratory methods

Monitoring of direct inhibitors of thrombin (DTI) is critical for their safe and effective use as anticoagulants. We examined samples containing several concentrations of argatroban or lepirudin in reconstituted standard human plasma and plasma from medical outpatients and intensive care patients. Prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin time (TT) were determined using automated analyzers. Ecarin clotting time (ECT) was measured using a 10 IU/mL dilution of ecarin in 0.05 mol/L CaCl(2). Calibration curves were approximately linear for TT and ECT in samples containing argatroban and lepirudin, respectively. Activated partial thromboplastin curves reached a plateau at DTI concentrations ≥2 µg/mL, suggesting that the aPTT may not reliably detect overdosing. Prothrombin time increased exponentially. A broad range of clotting times was seen in patient samples with all tests suggesting that individual morbidity and therapies may strongly influence test results and may lead to underestimation of DTI doses.

Pharmacist-Managed Direct Thrombin Inhibitor Protocol Improves Care of Patients with Heparin-Induced Thrombocytopenia

Use of direct-thrombin inhibitors (DTIs) for the management of patients with heparin-induced thrombocytopenia (HIT) is challenging. A pharmacist-managed DTI protocol was implemented to standardize and improve the care of patients with HIT. A background study that compared DTI protocol–treated patients to those who did not receive treatment with the DTI protocol found that significantly more of the DTI protocol–treated patients received care that was consistent with level 1 guidelines from the American College of Chest Physicians (41% vs 0%). Because outcomes were poor regardless of whether the DTI protocol was used, the protocol was revised to require pharmacist implementation and oversight. A follow-up study compared DTI protocol patients from the background study (non-pharmacist-managed) to the pharmacist-managed DTI protocol group. There were significantly fewer dosing errors, improved nursing documentation, and less reexposure to heparin when the pharmacist was responsible for managing the DTI protocol. A trend toward reduced bleeding was noted. The management of patients with HIT is complex, and there are a number of pitfalls that may lead to poor outcomes. DTIs are high-risk medications that require careful dosing and monitoring to minimize risk for adverse drug events. A DTI protocol may improve care of patients with HIT, and pharmacist oversight of DTI use can help to reduce risk for errors and adverse medication events.

Argatroban therapy for heparin-induced thrombocytopenia in ICU patients with multiple organ dysfunction syndrome: a retrospective study

Introduction

Heparin-induced thrombocytopenia (HIT) is a serious, prothrombotic, immune-mediated adverse reaction triggered by heparin therapy. When HIT is diagnosed or suspected, heparins should be discontinued, and an alternative, fast-acting, parenteral, nonheparin anticoagulation such as argatroban should be initiated. Limited and inconsistent data exist about dosing of argatroban in intensive care unit (ICU) patients with critical illnesses.

Methods

Retrospective analysis of 12 ICU patients with multiple organ dysfunction syndrome (MODS) treated with argatroban for suspected or diagnosed HIT.

Results

The 12 ICU patients with a mean platelet count of 46,000 ± 30,310 had a mean APACHE II score of 26.7 ± 7.8 on ICU admission and a mean SAPS II score of 61.5 ± 16.3 on the first day of argatroban administration. A mean argatroban starting dose of 0.32 ± 0.25 μg/kg/min (min, 0.04; max, 0.83) was used to achieve activated partial thromboplastin times (aPTTs) >60 sec or aPTTs of 1.5 to 3 times the baseline aPTT. Adjustment to aPTT required dose reduction in six (50%) patients. Patients were treated for a mean of 5.5 ± 3.3 days. The final mean dose in these critically ill patients was 0.24 ± 0.16 μg/kg/min, which is about one eighth of the usually recommended dose and even markedly lower than the previously suggested dose for critically ill ICU patients. In all patients, desired levels of anticoagulation were achieved. The mean argatroban dose was significantly lower in patients with hepatic insufficiency compared with patients without hepatic impairment (0.10 ± 0.06 μg/kg/min versus 0.31 ± 0.14 μg/kg/min; P = 0.026). The mean argatroban dose was significantly correlated with serum bilirubin (r = -0.739; P = 0.006).

Conclusions

ICU Patients with MODS and HIT can be effectively treated with argatroban. A decrease in the initial dosage is mandatory in this patient population. Further studies are needed to investigate argatroban elimination and dosage adjustments for critically ill patients.

Impact of renal function on argatroban therapy during percutaneous coronary intervention

Argatroban, a hepatically metabolized direct thrombin inhibitor, is approved for anticoagulation in patients with or at risk of heparin-induced thrombocytopenia (HIT) undergoing percutaneous coronary intervention (PCI). We investigated the effect of renal function on argatroban therapy during PCI. From previous argatroban studies in PCI, we evaluated relationships between estimated creatinine clearance (CrCl) and activated clotting times (ACTs), dosage, and outcomes in 219 patients with or at risk of HIT (HIT group, n = 67) or administered glycoprotein IIb/IIIa inhibition (non-HIT group, n = 152). Patients received an argatroban bolus (350 mcg/kg, HIT group; 250 or 300 mcg/kg, non-HIT group) then 25-30 mcg/kg/min (adjusted to achieve ACTs 300-450 s, HIT group) or 15 mcg/kg/min (target ACTs 275-325 s, non-HIT group), with additional 150-mcg/kg boluses if needed. Of 219 patients, 55 (25%) had CrCl <or= 60 ml/min (8 with CrCl <or= 30 ml/min). Regression analyses detected no association between CrCl (range 7-231 ml/min) and initial ACT (by bolus) or mean infusion dose. Multi-bolus usage was similar in patients with, versus without, CrCl <or= 60 ml/min. In the non-HIT group, CrCl was associated (P = 0.01) with the time to ACT <or= 160 s after argatroban cessation (approximately 17 min slower per 30-ml/min CrCl decrease). Eight patients (none with CrCl <or= 60 ml/min) had ischemic complications. Three patients (1 with CrCl 40 ml/min) experienced major bleeding. Argatroban dose adjustment for renal function appears unnecessary during PCI. Renal dysfunction may be associated with slower (by minutes) ACT effect decay after argatroban cessation. Argatroban is well tolerated in PCI patients with renal impairment.

Heparin-Induced Thrombocytopenia in the Intensive Care Unit

Heparin-induced thrombocytopenia (HIT) occurs following an immune reaction to the administration of heparin, which results in increased platelet activation and thrombocytopenia, and lead to arterial and venous thrombosis in untreated cases. It may be considered as an idiosyncratic, drug-induced reaction in which heparin injections result in the formation of complexes with platelet factor 4 (PF4), triggering an antibody-mediated reaction in certain individuals. Low platelet count in this instance is secondary to platelet aggregation and can lead to thrombotic complications by vascular occlusion and other mechanisms. Early recognition of this complication is essential to prevent life- and limb-threatening thrombosis. Therefore, it is important that intensive care physicians who administer heparin in different forms are aware of this potential adverse event and follow a regular plan in monitoring the platelet count while the patient is on heparin. In a patient whose platelet count falls while on heparin, when no other diagnostic possibilities can easily explain it, immediate withdrawal of any form of heparin and commencement of an alternative anticoagulant is necessary until the diagnosis of HIT is confirmed or excluded. At the same time, it is important that over-diagnosis of HIT is not made to avoid unwanted bleeding complications from the alternative anticoagulants. This review outlines the pathophysiology, diagnosis and management of HIT with a focus on the intensive care setting.

Prolonged elevation of plasma argatroban in a cardiac transplant patient with a suspected history of heparin-induced thrombocytopenia with thrombosis

BACKGROUND

Direct thrombin inhibitors (DTIs) provide an alternative method of anticoagulation for patients with a history of heparin-induced thrombocytopenia (HIT) or HIT with thrombosis (HITT) undergoing cardiopulmonary bypass (CPB). In the following report, a 65-year-old critically ill patient with a suspected history of HITT was administered argatroban for anticoagulation on bypass during heart transplantation. The patient required massive transfusion support (55 units of red blood cells, 42 units of fresh-frozen plasma, 40 units of cryoprecipitate, 40 units of platelets, and three doses of recombinant Factor VIIa) for severe intraoperative and postoperative bleeding.

STUDY DESIGN AND METHODS

Plasma samples from before and after CPB were analyzed postoperatively for argatroban concentration using a modified ecarin clotting time (ECT) assay.

RESULTS

Unexpectedly high concentrations of argatroban were measured in these samples (range, 0-32 microg/mL), and a prolonged plasma argatroban half life (t(1/2)) of 514 minutes was observed (published elimination t(1/2) is 39-51 minutes [< or = 181 minutes with hepatic impairment]).

CONCLUSIONS

Correlation of plasma argatroban concentration versus the patient's coagulation variables and clinical course suggest that prolonged elevated levels of plasma argatroban may have contributed to the patient's extended coagulopathy. Because DTIs do not have reversal agents, surgical teams and transfusion services should remain aware of the possibility of massive transfusion events during anticoagulation with these agents. This is the first report to measure plasma argatroban concentration in the context of CPB and extended coagulopathy.

Argatroban: a review of its use in the management of heparin-induced thrombocytopenia

Argatroban, a highly selective direct thrombin inhibitor, is indicated for use as an anticoagulant for the treatment and prophylaxis of thrombosis in patients with heparin-induced thrombocytopenia (HIT), and in patients undergoing percutaneous coronary intervention (PCI) who have, or are at risk for, HIT. Intravenous argatroban improved clinical outcomes and was generally well tolerated in adults with HIT or HIT with thrombosis syndrome (HITTS). In two pivotal, open-label, historically controlled studies in adults with HIT, the incidence of the primary composite endpoint (all-cause death, all-cause amputation, or new thrombosis) was significantly lower in argatroban recipients than in historical controls, and more argatroban recipients than historical controls stayed event-free during the study according to a Kaplan-Meier analysis. In adults with HITTS in these trials, although the incidence of the primary composite endpoint did not differ significantly between argatroban recipients and historical controls, a Kaplan-Meier analysis showed that more patients receiving argatroban than historical controls remained event-free during the study. Major and minor bleeding rates in argatroban recipients were generally similar to those in historical controls in these studies. Argatroban was also an effective anticoagulant in patients with HIT undergoing PCI in three small, uncontrolled trials, pooled data from which showed that most (>or=95%) patients achieved a satisfactory outcome of the PCI procedure and adequate anticoagulation (coprimary endpoints). It was generally well tolerated in these patients, with the incidence of major bleeding being <or=1.1%. The efficacy and safety of argatroban in pediatric patients has not been established. However, a small uncontrolled, preliminary study suggests that it may be useful in seriously ill pediatric patients requiring nonheparin anticoagulation.

Prefilter Bivalirudin for Preventing Hemofilter Occlusion in Continuous Renal Replacement Therapy

Objective:

To describe a case of successful bivalirudin use as a prefilter anticoagulant in continuous venovenous hemofiltration (CVVH).

Case Summary:

A 30-year-old male was brought to the hospital by ambulance with an anterior communicating artery subarachnoid hemorrhage, signs of intraparenchymal hemorrhage, and hydrocephalus. During the patient's complicated hospital course, he developed acute renal failure requiring CVVH, as well as hepatic insufficiency (Child-Pugh class B). Unfractionated heparin was used as a prefilter anticoagulant. After he had a positive heparin-induced thrombocytopenia (HIT) antibody test, prefilter heparin was discontinued in favor of bivalirudin. Filter survival and systemic activated partial thromboplastin time (aPTT) values were compared between prefilter heparin (n = 5) and bivalirudin (n = 4). Filter survival was similar (median 26 h with heparin vs 37 h with bivalirudin; p = 0.52). Prefilter bivalirudin 1–2.5 mg/hour (0.009–0.023 mg/kg/h) was effective in maintaining systemic aPTTs that were 1–1.4 times the reference range. Serotonin release assay and subsequent HIT antibodies were negative. The patient's renal function improved and CVVH was discontinued.

Discussion:

Critically ill patients requiring CVVH often need regional or systemic anticoagulation to prevent filter occlusion. In some patient populations, such as those with HIT or liver failure, prefilter heparin and regional citrate, respectively, may not be options. Alternative anticoagulants may be needed to avoid complications of frequent filter occlusions. The direct thrombin inhibitors (DTIs) lepirudin and argatroban have been used to maintain hemofilter patency, in small studies. Bivalirudin may have pharmacokinetic advantages over other DTIs when used in patients with hepatic and renal impairment. In our patient, bivalirudin provided a safe alternative to heparin therapy and was effective in maintaining hemofilter patency during CVVH.

Conclusions:

Prefilter bivalirudin may be an option to prevent filter occlusion in patients requiring continuous renal replacement therapy. Future studies are needed to validate the safety and efficacy of bivalirudin as a prefilter anticoagulant.

Clinical experience with argatroban for heparin-induced thrombocytopenia in a large teaching hospital

BACKGROUND

Argatroban is a direct thrombin inhibitor approved for the prophylaxis or treatment of thrombosis in patients with heparin-induced thrombocytopenia (HIT). The product monograph does not guide clinicians beyond specifying the initial dose of 2 μg/kg per minute (or 0.5 μg/kg per minute for patients with hepatic impairment). Some authors have suggested that in the intensive care unit (ICU) and for patients with acute cardiac disease and those with renal or hepatic dysfunction, this dose may result in a supratherapeutic activated partial thromboplastin time (aPTT).

OBJECTIVES

To evaluate the efficacy and safety of argatroban in adult patients with suspected HIT in a large teaching hospital, and to review dosing for patients in the ICU, patients with acute cardiac disease, and patients with renal or hepatic dysfunction.

METHODS

Charts of patients with suspected HIT who had received argatroban for at least 24 h between October 1, 2005, and October 1, 2007, at the Foothills Medical Centre, Calgary, Alberta, were examined retrospectively.

RESULTS

Thirty patients met the inclusion criteria, with charts available for review. Of these, 21 (70%) patients had an initial argatroban dose of 2 μg/kg per minute and 4 (13%) had an initial dose of 0.5 μg/kg per minute. The median duration of therapy was 6 days, and the mean dose was 2.14 μg/kg per minute. There were 122 dosage adjustments, the most common change being 0.5 μg/kg per minute, followed by adjustments of 1 and 0.1 μg/kg per minute. Six patients had supratherapeutic aPTT values (above 100 s), and none experienced major bleeding.

CONCLUSIONS

The results of this study suggest that an initial argatroban dose of 2 μg/kg per minute is appropriate for patients with no hepatic dysfunction. Patients with acute cardiac disease and critically ill patients may require lower doses of argatroban; however no dosage adjustments are required for patients with renal dysfunction.

Reducing harm associated with anticoagulation: practical considerations of argatroban therapy in heparin-induced thrombocytopenia

Argatroban is a hepatically metabolized, direct thrombin inhibitor used for prophylaxis or treatment of thrombosis in heparin-induced thrombocytopenia (HIT) and for patients with or at risk of HIT undergoing percutaneous coronary intervention (PCI). The objective of this review is to summarize practical considerations of argatroban therapy in HIT. The US FDA-recommended argatroban dose in HIT is 2 microg/kg/min (reduced in patients with hepatic impairment and in paediatric patients), adjusted to achieve activated partial thromboplastin times (aPTTs) 1.5-3 times baseline (not >100 seconds). Contemporary experiences indicate that reduced doses are also needed in patients with conditions associated with hepatic hypoperfusion, e.g. heart failure, yet are unnecessary for renal dysfunction, adult age, sex, race/ethnicity or obesity. Argatroban 0.5-1.2 microg/kg/min typically supports therapeutic aPTTs. The FDA-recommended dose during PCI is 25 microg/kg/min (350 microg/kg initial bolus), adjusted to achieve activated clotting times (ACTs) of 300-450 sec. For PCI, argatroban has not been investigated in hepatically impaired patients; dose adjustment is unnecessary for adult age, sex, race/ethnicity or obesity, and lesser doses may be adequate with concurrent glycoprotein IIb/IIIa inhibition. Argatroban prolongs the International Normalized Ratio, and published approaches for monitoring the argatroban-to-warfarin transition should be followed. Major bleeding with argatroban is 0-10% in the non-interventional setting and 0-5.8% periprocedurally. Argatroban has no specific antidote, and if excessive anticoagulation occurs, argatroban infusion should be stopped or reduced. Improved familiarity of healthcare professionals with argatroban therapy in HIT, including in special populations and during PCI, may facilitate reduction of harm associated with HIT (e.g. fewer thromboses) or its treatment (e.g. fewer argatroban medication errors).

Argatroban anticoagulation in intensive care patients: effects of heart failure and multiple organ system failure

We retrospectively evaluated argatroban dosing patterns, clinical outcomes, and the effects of heart failure and multiple organ system failure on dosing requirements in 65 adult, intensive care patients administered argatroban anticoagulation for clinically suspected heparin-induced thrombocytopenia (n=56) or history of heparin-induced thrombocytopenia (n=9). Argatroban was initiated then titrated to achieve target activated partial thromboplastin times 1.5 to 3 times normal control (ie, 42-84 seconds). Overall, argatroban was initiated at 1.14+/-0.62 microg/kg/min (mean+/-SD) and administered for 11.4+/-9.5 days, with comparable dosing patterns between patients with suspected, versus previous, heparin-induced thrombocytopenia. Sixty-four (98.5%) patients achieved target activated partial thromboplastin times, typically following no or one dose adjustment. Therapeutic doses were lower in patients with, versus without, heart failure (0.58+/-0.28 vs 0.97+/-0.6 microg/kg/min, P= .042) and decreased as the number of failed organ systems increased from 1 to 2 to =3 (1.10+/-0.67 vs 0.87+/-0.47 vs 0.58+/-0.47 microg/kg/min, P= .008). From argatroban initiation until patient discharge or death, 11 (16.9%) patients (3 off argatroban) developed thromboembolic complications; 14 (21.5%) died (11 off argatroban, 7 from multiple organ system failure); and 1 (1.5%) required amputation. Nine patients (13.8%) experienced bleeding, none fatal. This experience suggests that argatroban administered at approximately 1 micro/kg/min provides adequate levels of anticoagulation in many intensive care unit patients with suspected or previous heparin-induced thrombocytopenia. Reduced doses are needed when heart failure or multiple organ system failure is present.

Argatroban for anticoagulation in continuous renal replacement therapy

OBJECTIVE

Argatroban, a direct thrombin inhibitor, was evaluated for anticoagulation in continuous renal replacement therapy (CRRT) in critically ill patients with heparin-induced thrombocytopenia type II and acute renal failure. The investigation focused on predictors for the maintenance doses of argatroban with efficacy and safety of argatroban being secondary outcomes.

DESIGN

Prospective, dose finding study.

SETTING

Two intensive care units (medical and surgical) of a university hospital.

PATIENTS

Medical and surgical patients (n = 30) with acute or histories of heparin-induced thrombocytopenia type II and acute renal failure with necessity for CRRT.

INTERVENTION

CRRT with argatroban for anticoagulation.

MEASUREMENTS AND MAIN RESULTS

Critical illness severity scores Acute Physiology and Chronic Health Evaluation (APACHE)-II, Simplified Acute Physiology Score (SAPS) II, and the indocyanine green plasma disappearance rate (ICG-PDR) were correlated to the argatroban maintenance doses. These diagnostic tools can help to identify patients with the necessity for decreased argatroban doses. The following recommendations for argatroban dosing during CRRT could be determined: a loading dose of 100 microg/kg followed by a maintenance infusion rate (microg/kg/min), which can be calculated from the scores as follows: for APACHE II: 2.15-0.06 x APACHE II (r = -.81, p < 0.001); for SAPS II: 2.06-0.03 x SAPS II (r = -.8, p < 0.001); and for ICG-PDR: -0.35 + 0.08 x ICG-PDR (r = .89, p < 0.001). The efficacy and safety of anticoagulation during CRRT were determined by the steady state of blood urea nitrogen (32.16 +/- 18.02 mg/dL), mean filter patency at 24 hrs (98%), and the rate of bleeding episodes. Only two patients developed minor bleeding; no patient developed severe bleeding episodes.

CONCLUSION

In critically ill patients with heparin-induced thrombocytopenia type II and necessity for CRRT critical illness scores (APACHE II, SAPS II) or ICG-PDR can help to predict the required argatroban maintenance dose for anticoagulation. These predictors identify decreased argatroban dosing requirements resulting in effective and safe CRRT.

Role of citrate and other methods of anticoagulation in patients with severe liver failure requiring continuous renal replacement therapy

Anticoagulation is required during continuous renal replacement therapy to prevent filter clotting and optimize filter performance. However, anticoagulation may also be associated with serious bleeding complications. Patients with liver failure often suffer from underlying coagulopathy and are especially prone to anticoagulation complications. The aim of this review is to present the unique features of patients with hepatic injury in terms of anticoagulation disorders and to analyze data on safety and efficacy of the different anticoagulation methods for liver failure patients undergoing continuous renal replacement therapy.

Treatment and prevention of heparin-induced thrombocytopenia: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This chapter about the recognition, treatment, and prevention of heparin-induced thrombocytopenia (HIT) is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patient values may lead to different choices. Among the key recommendations in this chapter are the following: For patients receiving heparin in whom the clinician considers the risk of HIT to be > 1.0%, we recommend platelet count monitoring over no platelet count monitoring (Grade 1C). For patients who are receiving heparin or have received heparin within the previous 2 weeks, we recommend investigating for a diagnosis of HIT if the platelet count falls by >/= 50%, and/or a thrombotic event occurs, between days 5 and 14 (inclusive) following initiation of heparin, even if the patient is no longer receiving heparin therapy when thrombosis or thrombocytopenia has occurred (Grade 1C). For patients with strongly suspected (or confirmed) HIT, whether or not complicated by thrombosis, we recommend use of an alternative, nonheparin anticoagulant (danaparoid [Grade 1B], lepirudin [Grade 1C], argatroban [Grade 1C], fondaparinux [Grade 2C], or bivalirudin [Grade 2C]) over the further use of unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) therapy or initiation/continuation of vitamin K antagonists (VKAs) [Grade 1B]. The guidelines include specific recommendations for nonheparin anticoagulant dosing that differ from the package inserts. For patients with strongly suspected or confirmed HIT, we recommend against the use of vitamin K antagonist (VKA) [coumarin] therapy until after the platelet count has substantially recovered (usually, to at least 150 x 10(9)/L) over starting VKA therapy at a lower platelet count (Grade 1B); that VKA therapy be started only with low maintenance doses (maximum, 5 mg of warfarin or 6 mg of phenprocoumon) over higher initial doses (Grade 1B); and that the nonheparin anticoagulant (eg, lepirudin, argatroban, danaparoid) be continued until the platelet count has reached a stable plateau, the international normalized ratio (INR) has reached the intended target range, and after a minimum overlap of at least 5 days between nonheparin anticoagulation and VKA therapy rather than a shorter overlap (Grade 1B). For patients receiving VKAs at the time of diagnosis of HIT, we recommend use of vitamin K (10 mg po or 5 to 10 mg IV) [Grade 1C].

Reduced Argatroban Doses After Coronary Artery Bypass Graft Surgery

Background:

The Food and Drug Administration–approved argatroban dose for heparin-induced thrombocytopenia (HIT) is 2 μg/kg/min (0.5 μg/kg/min in hepatic impairment), adjusted to achieve activated partial thromboplastin time (aPTT) 1.5–3 times baseline. Recent data suggest that reduced doses are required after cardiovascular surgery.

Objective:

To characterize dosing requirements, aPTTs, factors affecting dosage, and clinical outcomes in patients administered argatroban after coronary artery bypass graft (CABG) surgery.

Methods:

Charts of 39 patients who underwent CABG surgery and were administered argatroban postoperatively for laboratory-confirmed HIT (n = 25), antibody-negative suspected HIT (n = 10), or previous HIT requiring anticoagulation (n = 4) were retrospectively reviewed. Patient characteristics, argatroban dosing information, aPTTs (target range 45–90 sec), and outcomes were summarized. Regression analyses explored potential effectors of dosage.

Results:

Patient features, argatroban dosing patterns, and aPTTs were similar among groups. Many patients had laboratory evidence of some hepatic and/or renal dysfunction (median [range] bilirubin 1.0 [0.3–8.0] mg/dL, creatinine clearance 47 [18–287] mL/min). Overall, median argatroban doses were 0.5 μg/kg/min initially and 0.6 μg/kg/min during therapy (median duration 5.3 days). After argatroban initiation, aPTTs were greater than 90 seconds at first assessment in 4 patients (3 with abnormal hepatic function test results) initially administered 0.5, 1, 2, and 2 μg/kg/min, respectively. Within approximately 16 hours of therapy, 33 (85%) patients achieved consecutive therapeutic aPTTs. No association was detected between mean dose during therapy and preoperative ejection fraction, routine hepatic or renal function test results (other than blood urea nitrogen [BUN]), or surgery type. A clinically insignificant association existed between dose and BUN: there was an approximately 0.15 μg/kg/min dose decrease for each 10 mg/dL BUN increase. One patient developed thrombosis, 1 underwent finger amputation, 7 died (5 after argatroban cessation), and 4 had significant bleeding.

Conclusions:

These findings suggest that reduced initial argatroban doses (eg, 0.5 μg/kg/min), adjusted to achieve therapeutic aPTTs, provide rapid, adequate anticoagulation in postoperative CABG patients with presumed or previous HIT. Prospective study of reduced initial dosing in this setting is warranted.