Anticoagulant therapy by continuous heparin-antithrombin III infusion in newborns with disseminated intravascular coagulation

Use and Future Investigations of Recombinant and Plasma-Derived Coagulation and Anticoagulant Products in the Neonate

Although congenital bleeding disorders can manifest in the newborn period, the most common causes of bleeding and thrombosis in neonates are acquired conditions. Factor concentrates are used for specific diagnoses (hemophilia with inhibitors, specific factor deficiency, von Willebrand disease) and approved indications, and increasingly for off-label indications (bleeding in surgery cardiopulmonary bypass, extracorporeal membrane oxygenation). We will review the approved indications for factor products in the neonate and discuss the evidence and rationale for off-label use of factor products in management of bleeding and thrombosis in the neonate.

Recombinant soluble human thrombomodulin (thrombomodulin alfa) in the treatment of neonatal disseminated intravascular coagulation

Recombinant soluble human thrombomodulin (TM-α) has been shown to be useful in the treatment of disseminated intravascular coagulation (DIC) in a heparin-controlled study and has been available for clinical use in Japan since 2008. However, data on its use for neonatal DIC have not been reported from any clinical studies, so efficacy and safety were analyzed in 60 neonatal DIC patients identified in post-marketing surveillance. The DIC resolution rate as of the day after last administration of TM-α was 47.1 %, and the survival rate at 28 days after last administration was 76.7 %. Hemostatic test result profiles revealed decreased levels of fibrin/fibrinogen degradation products and increased platelet counts and antithrombin activity. Incidences of adverse drug reactions, bleeding-related adverse drug reactions, and bleeding-related adverse events were 6.7, 6.7, and 16.7 %, respectively, with no significant differences between neonatal, pediatric (excluding neonates), and adult DIC patients.

CONCLUSION

This surveillance provided real-world data on the safety and effectiveness of TM-alpha in the treatment of neonatal DIC in general practice settings.

Antithrombin concentrate use in children: a multicenter cohort study

OBJECTIVE

To describe the off-label use of antithrombin concentrate in tertiary care pediatric hospitals across the US.

STUDY DESIGN

This is a retrospective, multicenter, cohort study of 4210 admissions of children younger than 18 years of age who received antithrombin concentrate between 2002 and 2011 within the Pediatric Health Information System administrative database. An on-label admission was defined as an admission with an International Classification of Diseases diagnostic code for a primary hypercoagulable state; admissions without this code were classified as off-label.

RESULTS

During the 10-year study period, off-label use of antithrombin concentrate increased 5-fold. Overall, 97% of study subjects received antithrombin off-label. Neonates younger than 30 days of age comprised the largest age group (45.7%) of use; 87% of patients had at least one complex chronic condition, with congenital heart/lung defects being the most prevalent primary diagnosis (36.3%). Extracorporeal membrane oxygenation was the most common procedure associated with antithrombin use (43.7%).

CONCLUSIONS

The off-label use of antithrombin concentrate is increasing rapidly, particularly in critically ill children receiving extracorporeal membrane oxygenation, with few parallel studies to substantiate its safety or efficacy. Further preclinical and controlled clinical studies are critical to expanding our knowledge of this drug. In the meantime, antithrombin concentrate should be used judiciously by clinicians and following guidelines instated by hospitals.

A clinical audit of antithrombin concentrate use in a tertiary paediatric centre

AIM

  The aim of this study was to investigate the clinical use of antithrombin concentrate (ATC) in children and specifically to determine the current practice of ATC administration, including dosing and indications for administration.

METHODS

  A clinical audit was performed of patients treated with ATC during two 12-month periods: 1 June 1999-1 June 2000 and 1 June 2009-1 June 2010.

RESULTS

  Thirty-seven patients whose age ranged from 1 day to 13.5 years (median 30 days) received a median of two doses (range 1-15) with a median dose of 40 units/kg (range 1-200 units). The majority (90%) of patients were located in the intensive care unit, and the major indication (76%) for use of the ATC was in the setting of unfractionated heparin (UFH) resistance. Post-ATC administration, 32% of the doses given resulted in antithrombin levels reaching age-specific normative levels. Of the patients administered ATC with the aim of optimising UFH therapy, 28% of patients had their UFH dose reduced without any measurement of UFH effect.

CONCLUSIONS

  This data provides the basis for future investigations of the specific biochemical changes accompanying ATC administration and the development of paediatric-specific evidence-based guidelines for ATC use.

Anticoagulation in neonates and children: Pitfalls and dilemmas

Anticoagulation in children is problematic for many reasons, related to the patient population as well as the anticoagulant drugs themselves. This paper describes the multitude of reasons why providing anticoagulation therapy in children is different from anticoagulation therapy in adults, and hence why dedicated paediatric anticoagulant services are the ideal structure to provide this service. The paper then describes the three most common anticoagulants used in children, and details specifically what is and is not known about them in the paediatric population. Finally the paper addresses the issue of how best to introduce newer anticoagulant drugs into the paediatric population. There remains much research to be done in this field, in the meantime clinicians need to carefully consider the evidence available to them and manage each individual patient accordingly.

Antithrombin III for critically ill patients

BACKGROUND

Critical illness is associated with uncontrolled inflammation and vascular damage which can result in multiple organ failure and death. Antithrombin III (AT III) is an anticoagulant with anti-inflammatory properties but the efficacy and any harmful effects of AT III supplementation in critically ill patients are unknown.

OBJECTIVES

To assess the benefits and harms of AT III in critically ill patients.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library); MEDLINE; EMBASE; Science Citation Index Expanded; International Web of Science; CINAHL; LILACS; and the Chinese Biomedical Literature Database (up to November 2006). We contacted authors and manufacturers in the field.

SELECTION CRITERIA

We included all randomized clinical trials, irrespective of blinding or language, that compared AT III with no intervention or placebo in critically ill patients.

DATA COLLECTION AND ANALYSIS

Our primary outcome measure was mortality. We each independently abstracted data and resolved any disagreements by discussion. We presented pooled estimates of the intervention effects on dichotomous outcomes as relative risks (RR) with 95% confidence intervals (CI). We performed subgroup analyses to assess risk of bias, the effect of AT III in different populations (sepsis, trauma, obstetric, and paediatric patients), and the effect of AT III in patients with or without the use of concomitant heparin. We assessed the adequacy of the available number of participants and performed a trial sequential analysis to establish the implications for further research.

MAIN RESULTS

We included 20 randomized trials with a total of 3458 participants; 13 of these trials had high risk of bias. When we combined all trials, AT III did not statistically significantly reduce overall mortality compared with the control group (RR 0.96, 95% CI 0.89 to 1.03; no heterogeneity between trials). A total of 32 subgroup and sensitivity analyses were carried out. Analyses based on risk of bias, different populations, and the role of adjuvant heparin gave insignificant differences. AT III reduced the multiorgan failure score among survivors in an analysis involving very few patients. AT III increased bleeding events (RR 1.52, 95% CI 1.30 to 1.78).

AUTHORS' CONCLUSIONS

AT III cannot be recommended for critically ill patients based on the available evidence. A randomized controlled trial of AT III, without adjuvant heparin, with prespecified inclusion criteria and good bias protection is needed.

Neonatal thromboembolic emergencies

Thrombosis risk is multifactorial, with interaction of hereditary risk factors and acquired environmental and clinical conditions. Newborns are at particular risk for thrombotic emergencies secondary to the unique properties of their hemostatic system, influences of the maternal-fetal environment, and perinatal complications and interventions. Thrombotic complications range from arterial and venous catheter thrombosis to purpura fulminans. Prompt identification and appropriate management of thrombotic emergencies is critical in avoiding limb-, organ-, and life-threatening complications. Treatment strategies have been extrapolated from adult literature but clinical experience from small-scale neonatal studies has resulted in therapeutic guidelines, which should be individualized for each neonate, taking into consideration age and clinical status.

Antithrombin III (AT) and recombinant tissue plasminogen activator (R-TPA) used singly and in combination versus supportive care for treatment of endotoxin-induced disseminated intravascular coagulation (DIC) in the neonatal pig

BACKGROUND

Disseminated intravascular coagulation (DIC) is a pathological disturbance of the complex balance between coagulation and anticoagulation that is precipitated by vascular injury, acidosis, endotoxin release and/or sepsis and characterized by severe bleeding and excessive clotting. The innately low levels of coagulation factors found in newborn infants place them at extremely high risk for DIC. Anecdotal reports suggest that either anticoagulant or fibrinolytic therapy may alleviate some of the manifestations of DIC. To test the hypothesis that replacement of both anticoagulants and fibrinolytics may improve survival and outcome better than either single agent or supportive care alone, we utilized a neonatal piglet model of endotoxin-induced DIC.

METHODS

DIC was induced in twenty-seven neonatal pigs (7 to 14 days of age) by intravenous administration of E. coli endotoxin (800 microg/kg over 30 min). The piglets were divided into 4 groups on the basis of treatment protocol [A: supportive care alone; B: Antithrombin III (AT, 50 microg/kg bolus, 25 microg/kg per hr continuous infusion) and supportive care; C: Recombinant Tissue Plasminogen Activator (R-TPA, 25 microg/kg per hr continuous infusion) and supportive care; D: AT, R-TPA and supportive care] and monitored for 3 primary outcome parameters (survival time, macroscopic and microscopic organ involvement) and 4 secondary outcome parameters (hematocrit; platelet count; fibrinogen level; and antithrombin III level).

RESULTS

Compared with supportive care alone, combination therapy with AT and R-TPA resulted in a significant improvement of survival time, hematocrit, AT level, macroscopic and microscopic organ involvement, p < 0.05. Compared with supportive care alone, R-TPA alone significantly reduced macroscopic organ involvement and AT alone increased AT levels.

CONCLUSION

The findings suggest that combining AT, R-TPA and supportive care may prove more advantageous in treating the clinical manifestations of DIC in this neonatal pig model than either single modality or supportive care alone.

Pediatric hemostasis and use of plasma components

Indications for fresh frozen plasma (FFP), once used routinely in the support of critically ill infants and children, have become more specific as evolving evidence has confirmed or disproved the efficacy of plasma in various circumstances. FFP is currently indicated to treat the coagulopathies of massive hemorrhage, liver failure and disseminated intravascular coagulation and sepsis. Whole blood reconstituted from FFP and packed red cells is the product of choice for exchange transfusion, as well as for circuit priming. In the US, FFP remains the only approved source of factors V, XI, protein C, protein S and plasminogen. Cryoprecipitate is used chiefly as a source of fibrinogen, factor VIII and factor XIII in consumptive coagulopathy; recombinant or viral inactivated plasma derivatives are preferred for congenital deficiencies of factor VIII and von Willebrand factor. Recombinant and highly purified, viral inactivated, plasma-derived proteins are preferred over FFP for congenital and acquired deficiencies. This chapter reviews evidence to support the use of plasma and plasma derivatives for pediatric patients.

Venous thromboembolic events in pediatric patients. Diagnosis and management

Venous thromboembolism is a rapidly increasing secondary complication in children being treated for serious, life-threatening, primary diseases. Most current management guidelines and recommendations for imaging techniques have been extrapolated from the results of trials in adults. This may be less than optimal for children as there are important differences. The purpose of this article is to summarize the information on venous thromboembolism in children, and offer some guidelines for diagnosis, prophylaxis, and therapeutic intervention based on the best available evidence.

High dose of intravenous antithrombin III without heparin in the treatment of disseminated intravascular coagulation and organ failure in four children

In several animal experiments, high doses of antithrombin III concentrates have shown beneficial effects on mortality and reversal of coagulation abnormalities which had resulted from disseminated intravascular coagulation. Other experiments have suggested that antithrombin III infusion without heparin is effective in the treatment of organ failure. We clinically treated children suffering disseminated intravascular coagulation only with antithrombin concentrate. Four patients suffering disseminated intravascular coagulation with organ failure were selected. We started antithrombin III concentrate infusion as soon as the diagnosis was established. The dosage of antithrombin III was 120-250 units/kg/day for 2 or 3 days. Heparin was not used. All 4 patients recovered completely and quickly without any complications within 14 days. We suggest that the high-dose antithrombin III infusion without heparin is an effective and safe therapy for disseminated intravascular coagulation with organ failure.

Indications and drugs for anticoagulation therapy in children

The indications for using anticoagulants in children are reviewed. These include venous thromboembolic disease, thrombosis associated with central venous lines, inherited conditions, arterial thromboembolic disease and umbilical catheterization. The anticoagulants presently available for paediatric use consist of heparin and oral agents including low molecular weight heparin (LMWH). The problems associated with their use in children are examined and potential advantages described. Increasing numbers of children are now requiring anticoagulant therapy and the potential advantages of LMWHs makes it imperative that randomized, controlled trials be carried out in children in prophylactic as well as therapeutic situations.

Use of antithrombin III in critical patients

OBJECTIVE

To evaluate the effect of the AT III concentrates upon the clinical evolution and hemostatic parameters.

DESIGN

Prospective, open, randomized trial.

PATIENTS AND PARTICIPANTS

Septic and multiple trauma patients admitted to our Intensive Care Unit.

SETTING

Levels of AT III below 70% were used as criteria to choose 36 patients, 20 of whom received treatment with AT III and 16 did not.

INTERVENTIONS

AT III concentrates were administered at an initial dose of 60 U/kg followed by 10 U/kg every six hours.

RESULTS

The administration of AT III neither contributes to alterations in haemostasis, nor the clinical evolution (evaluated according to Apache II score).

CONCLUSIONS

The results suggest that the administration of AT III concentrates to critical patients with acquired low levels, but without manifest DIC, may not be justified; although further studies on a larger population are required to establish definite conclusions.

A pilot study of antithrombin replacement in intensive care management: the effects on mortality, coagulation and renal function

A prospective, randomized, controlled trial to examine the effects of antithrombin supplementation on mortality, coagulation and renal function has been carried out on 132 intensive care patients. Antithrombin activity was measured in all patients on admission to the intensive care unit (ICU). Patients with an antithrombin activity of less than 70% were randomized to either receive antithrombin replacement or to act as controls. Antithrombin activity was maintained above 70% in the treated patients throughout their stay on ICU. Ninety-three patients had an antithrombin activity of less than 70% and 35 received replacement therapy. Patients with antithrombin activity below 70% remained on the ICU significantly longer and had a significantly higher mortality rate than patients with antithrombin activity above 70%. Antithrombin supplementation neither reduced mortality nor shortened the intensive care stay. Fifty patients with reduced antithrombin activity remained on the ICU for at least 4 days, 25 received antithrombin and 25 acted as controls; coagulation parameters and renal function have been monitored in these patients. Fibrinogen concentration and platelet count were unaffected by antithrombin replacement. Antithrombin supplementation did not appear to reduce the incidence of impaired renal function in sepsis, trauma and postoperative patients. The creatinine clearance fell below 20 ml/min in eight patients in the no-treatment arm while by comparison only three patients in the treatment arm developed impaired renal function. Our study does not demonstrate a clear role for the use of antithrombin supplementation in intensive care, however the finding that antithrombin reduced renal impairment is encouraging and a larger study to confirm this finding is at present underway.

Efficacy of antithrombin III supplementation in animal models of fulminant Escherichia coli endotoxemia or bacteremia

Plasma antithrombin III (ATIII) levels decrease early during gram-negative septicemia, and even a moderate decrease in this major inhibitor of the coagulation system is associated with serious disseminated intravascular coagulation (DIC). Herein the efficacy of high-dose (at least 250 units/kg) ATIII supplementation in animal models of Escherichia coli endotoxemia or bacteremia is reported. An endotoxemic rat model demonstrated that: (1) DIC occurs very early, before the appearance of deleterious cardiovascular abnormalities; (2) ATIII prophylaxis attenuates DIC, metabolic dysfunction, and organ damage; (3) ATIII prophylaxis increases permanent survival; (4) ATIII treatment one hour after endotoxin challenge attenuates DIC, metabolic dysfunction, and organ damage, although not as well as when given prophylactically, and survival is not increased. An endotoxemic sheep pulmonary dysfunction model demonstrated that: (1) ATIII prophylaxis prevents the typical decrease in arterial oxygen partial pressure; (2) ATIII prophylaxis combined with alpha-1-proteinase inhibitor significantly attenuates indices of pulmonary dysfunction. An E. coli bacteremic baboon model demonstrated that ATIII prophylaxis and treatment significantly attenuate indices of DIC and organ damage and prevent death in an otherwise completely lethal dose bacterial challenge. In conclusion, prophylactic treatment with high doses of ATIII may be efficacious in disease states of impending disseminated intravascular coagulation, such as primary or secondary gram-negative septicemia.

Acquired antithrombin III deficiency: laboratory diagnosis, incidence, clinical implications, and treatment with antithrombin III concentrate

Antithrombin III (ATIII) is the predominant naturally occurring inhibitor of serine proteases generated during blood coagulation [Rosenberg RD: Annu Rev Med 1978; 29: 367-378]. Since 1965, several assays have been developed that allow rapid and precise determination of ATIII in plasma. As a consequence, the existence of acquired ATIII deficiency in many pathologic conditions has been described. Acquired ATIII deficiency is based on decreased synthesis, increased loss or increased consumption, or induced by drugs. An inherited ATIII deficiency is associated with a lifelong tendency to venous thromboembolism. In contrast, the clinical significance of acquired ATIII deficiency has been less well defined. A precise estimate of the risk of thromboembolism in the acquired ATIII deficiency state cannot easily be provided, owing to the lack of studies in consecutive patients. In 1978, a purified human ATIII concentrate became available for clinical investigation. Despite numerous small studies, the value of ATIII replacement therapy in patients with acquired deficiency remains to be demonstrated.

Neonatal antithrombin III deficiency

Hemorrhagic and thrombotic complications are common in sick preterm infants and may reflect inadequate regulation of coagulation. All neonates have low levels of the pivotal regulator antithrombin III (ATIII) compared with adults. Plasma levels of ATIII are very low in preterm infants and are further diminished in infants with respiratory distress, necrotizing enterocolitis, sepsis, or disseminated intravascular coagulation. Babies with lower levels of ATIII in the cord blood have been shown to have a worse outcome than neonates with levels appropriate for gestational age, including higher mortality and increased incidence of intracranial hemorrhages and catheter-related thromboses. The origin of severe ATIII deficiency is unknown. Therapies with plasma replacement or anticoagulation have decreased the incidence and severity of hemorrhagic and thrombotic complications in high-risk infants in several clinical trials. These data lay the groundwork and rationale for potential use of ATIII replacement in deficient preterm infants.