Age-related reference values for activation markers of the coagulation and fibrinolytic systems in children

Age-based difference in activation markers of coagulation and fibrinolysis in extracorporeal membrane oxygenation

OBJECTIVE

Coagulation system activation in extracorporeal membrane oxygenation results in hemostatic derangements. Thrombin generation markers like prothrombin fragment 1+2 and thrombin-antithrombin complex are sensitive markers of hypercoagulability. Plasmin-antiplasmin complex is a sensitive marker for fibrinolysis. D-dimers reflect thrombin generation and fibrinolysis. The aim was to identify the extent of hemostasis activation during extracorporeal membrane oxygenation by measuring thrombin-antithrombin complex, prothrombin fragment 1+2, plasmin-antiplasmin complex, and D-dimer.

DESIGN

Prospective cohort study.

SETTING

Tertiary care academic center.

PATIENTS

Children placed on extracorporeal membrane oxygenation from April 2011 to January 2013.

INTERVENTIONS

Prothrombin fragment 1+2, thrombin-antithrombin complex, plasmin-antiplasmin complex, and D-dimer were measured on days 1 and 5 of extracorporeal membrane oxygenation.

MEASUREMENTS AND MAIN RESULTS

Data presented as median (interquartile range); nonparametric tests were done using SPSS. Twenty-nine children (52% < 30 d old [neonates], median extracorporeal membrane oxygenation length 151 hr) were studied. Complications included thrombosis in 14%, bleeding in 45%, and thrombosis and bleeding together in 10%. Thrombin-antithrombin complex, prothrombin fragment 1+2, plasmin-antiplasmin complex, and D-dimer levels were high on day 1 and remained increased on extracorporeal membrane oxygenation. In neonates, all levels were higher on day 5 compared with day 1: thrombin-antithrombin complex (55.6 μg/L [30.7-76.0] vs 18.7 μg/L [10.9-34.6]; p = 0.03), prothrombin fragment 1+2 (2,038 pmol/L [1,093-4,018.5] vs 377.5 pmol/L [334.3-1,103.0]; p = 0.00), plasmin-antiplasmin complex (2,160 μg/L [786-3,090] vs 398 μg/L [296.8-990.8]; p = 0.00), and D-dimer (3.0 μg/mL [1.9-11.5] vs 1.5 μg/mL [0.6-2.9]; p = 0.01). Thrombin-antithrombin complex, prothrombin fragment 1+2, plasmin-antiplasmin complex, and D-dimer levels did not correlate with anti-Xa activity or heparin dose. In bleeders older than 30 days, plasmin-antiplasmin complex stayed elevated on day 5, but in patients with no bleeding complications, plasmin-antiplasmin level showed a declining trend. In neonates, plasmin-antiplasmin levels increased over the course of extracorporeal membrane oxygenation irrespective of bleeding.

CONCLUSION

Despite our best efforts at adequate anticoagulation with unfractionated heparin, neonates showed persistent increase in coagulation activation on extracorporeal membrane oxygenation. Fibrinolysis activation may contribute to bleeding in patients older than 30 days. Different anticoagulation protocols should be individualized based on age.

Coagulopathy associated with traumatic brain injury

Coagulopathy is often observed after traumatic brain injury (TBI), but the pathogenic mechanisms of this phenomenon remain elusive. Brain injury is the leading cause of trauma deaths, and the development of coagulopathy after TBI is associated with increased morbidity and mortality in these patients. The coagulopathy after TBI comprises a hypocoagulable and a hypercoagulable state with hemorrhagic and thrombotic phenotypes that are both associated with worse outcome. Some theories of its pathogenesis include massive release of tissue factor, altered protein C homeostasis, microparticle upregulation, and platelet hyperactivity. This article aims to examine the coagulopathy associated with blunt head injury, to review its effect on progression of hemorrhagic injury, and to discuss the possible relevant pathophysiological mechanisms.

Pharmacokinetic, pharmacodynamic and intracellular effects of PEG-asparaginase in newly diagnosed childhood acute lymphoblastic leukemia: results from a single agent window study

L-asparaginase is an effective drug for treatment of children with acute lymphoblastic leukemia (ALL). The effectiveness is thought to result from depletion of asparagine in serum and cells. We investigated the clinical response in vivo of 1000 IU/m(2) pegylated (PEG)-asparaginase and its pharmacokinetic, pharmacodynamic and intracellular effects in children with newly diagnosed ALL before start of combination chemotherapy. The in vivo window response was significantly related to immunophenotype and genotype: 26/38 common/pre B-ALL cases, especially those with hyperdiploidy and TELAML1 rearrangement, demonstrated a good clinical response compared to 8/17 T-ALL (P=0.01) and BCRABL-positive ALL (P=0.04). A poor in vivo clinical window response was related to in vitro resistance to L-asparaginase (P=0.02) and both were prognostic factors for long-term event-free survival (hazard ratio 6.4, P=0.004; hazard ratio 3.7, P=0.01). After administration of one in vivo dose of PEG-asparaginase no changes in apoptotic parameters or in intracellular levels of twenty amino acids in leukemic cells could be measured, in contradiction to the changes found after in vitro exposure. This may be explained by the rapid removal of apoptotic cells from the circulation in vivo. One additional dose of PEG-asparaginase upfront ALL treatment did not lead to other severe toxicities.

Children undergoing cardiac surgery for complex cardiac defects show imbalance between pro- and anti-thrombotic activity

Introduction

Cardiac surgery with cardiopulmonary bypass (CPB) is associated with the activation of inflammatory mediators that possess prothrombotic activity and could cause postoperative haemostatic disorders. This study was conducted to investigate the effect of cardiac surgery on prothrombotic activity in children undergoing cardiac surgery for complex cardiac defects.

Methods

Eighteen children (ages 3 to 163 months) undergoing univentricular palliation with total cavopulmonary connection (TCPC) (n = 10) or a biventricular repair (n = 8) for complex cardiac defects were studied. Prothrombotic activity was evaluated by measuring plasma levels of prothrombin fragment 1+2 (F1+2), thromboxane B₂ (TxB2), and monocyte chemoattractant protein-1 (MCP-1). Anti-thrombotic activity was evaluated by measuring levels of tissue factor pathway inhibitor (TFPI) before, during, and after cardiac surgery.

Results

In all patients, cardiac surgery was associated with a significant but transient increase of F1+2, TxB2, TFPI, and MCP-1. Maximal values of F1+2, TxB2, and MCP-1 were found at the end of CPB. In contrast, maximal levels of TFPI were observed at the beginning of CPB. Concentrations of F1+2 at the end of CPB correlated negatively with the minimal oesophageal temperature during CPB. Markers of prothrombotic activity returned to preoperative values from the first postoperative day on. Early postoperative TFPI levels were significantly lower and TxB2 levels significantly higher in patients with TCPC than in those with biventricular repair. Thromboembolic events were not observed.

Conclusion

Our data suggest that children with complex cardiac defects undergoing cardiac surgery show profound but transient imbalance between pro- and anti-thrombotic activity, which could lead to thromboembolic complications. These alterations are more important after TCPC than after biventricular repair but seem to be determined mainly by low antithrombin III.

Changes in hypercoagulability by asparaginase: a randomized study between two asparaginases

Alterations in hemostasis have frequently been observed in children with acute lymphoblastic leukemia. Thrombotic events are well documented in patients receiving L-asparaginase as a single agent or in combination with other chemotherapeutic drugs. The present prospective, randomized study evaluated the effect of two different L-asparaginase preparations, native Escherichia coli L-asparaginase (Crasnitin; Bayer AG, Leverkusen, Germany; n = 10) and L-asparaginase derived from Erwinia chrysanthemi (Erwinase; Porton Pruducts, London, UK; n = 10) on the changes in parameters concerning hypercoagulability. Patients were randomized to receive a total of eight doses of 10,000 IU/m2 L-asparaginase intravenously with intervals of 3 days during induction therapy. Before starting L-asparaginase treatment all patients had already demonstrated an increased thrombin generation shown by the elevated levels of prothrombin fragment 1+2 and thrombin antithrombin III, presumably due to therapy with prednisone, daunorubicin and vincristine. A significant decrease in alpha2-antiplasmin and plasminogen levels was measured in the E. coli L-asparaginase but not in Erwinase-treated patients. Increased thrombin generation combined with a decrease in alpha2-antiplasmin and plasminogen levels may lead to a state of increased risk for thrombosis due to a delay in fibrin elimination in E. coli L-asparaginase-treated patients only.

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.

Maternal thrombophilia and neonatal thrombosis

In neonates and infants, numerous clinical and environmental conditions lead to elevated thrombin generation and subsequent thrombus formation. Genetic prothrombotic defects (protein C, protein S and antithrombin deficiency, mutations of coagulation factor V and factor II, elevated lipoprotein (a)) have been established as risk factors of thromboembolic events in neonates and infants. The interpretation of the laboratory evaluation relies on age-dependent normal reference values. Because appropriate clinical trials are missing in these age groups, treatment recommendations are adapted from small-scale studies in neonates and infants and from guidelines relating to adult patient protocols. Secondary long-term anticoagulation should be administered on an individual basis.

The imbalance between coagulation and fibrinolysis is related to the severity of the illness and the prognosis in sepsis

OBJECTIVES

The coagulation and fibrinolytic system appears to be activated by the septic process independently, leading to the syndrome of disseminated intravascular coagulation (DIC). In this study, we investigated the changes within the hemostatic system related to the severity of the illness and the prognosis in patients with sepsis.

METHODS

Plasma thrombin-antithrombin III (TAT) and plasmin-alpha 2-antiplasmin (PAP) complexes were measured using ELISA methods in 32 patients with sepsis and 20 controls and were analyzed according to the APACHE III scores and survival of the patients.

RESULTS

Plasma TAT and PAP in patients with sepsis were significantly higher than controls. Nonsurvivors showed greater levels of TAT (21.7 +/- 22.3 ng/mL) and lower levels of PAP (628.4 +/- 378.1 ng/mL) than survivors (TAT: 11.1 +/- 11.2 ng/mL; PAP: 857.1 +/- 364.1 ng/mL). The imbalance between coagulation and fibrinolysis described as TAT/PAP ratio was closely related with APACHE III scores in patients with sepsis (r = 0.47) and the TAT/PAP ratio in nonsurvivors was significantly higher compared with survivors (34.4 +/- 21.4 vs. 14.4 +/- 13.8).

CONCLUSION

In sepsis, both coagulation and the fibrinolysis system are activated and the imbalance between coagulation and fibrinolysis predisposes to the hypercoagulation state and is closely related to the severity of the disease and the prognosis.

Effects of physical training and its cessation on the hemostatic system of obese children

BACKGROUND

Physical training can improve hemostatic function in adults, thereby reducing heart disease risk, but no information is available in children on whether physical training can enhance hemostatic function.

OBJECTIVE

The purpose of this investigation was to examine the effects of a physical training program on hemostatic variables in a biethnic group of obese children.

DESIGN

Children were randomly assigned to 2 groups. Group 1 participated in physical training for 4 mo and then ceased physical training for 4 mo, whereas group 2 did no physical training for the first 4 mo and then participated in physical training for 4 mo. Plasma hemostatic variables [fibrinogen, plasminogen activator inhibitor 1 (PAI-1), and D-dimer) were measured at months 0, 4, and 8.

RESULTS

Analyses of variance revealed no significant group-by-time interactions for the hemostatic variables. When data from both groups were combined there was a significant decrease in D-dimer after 4 mo of physical training (P < 0.05). Factors explaining individual differences in responsiveness to the physical training revealed that individuals with greater percentage fat before physical training showed greater reductions in fibrinogen and D-dimer, and that blacks showed greater reductions in D-dimer than whites (P < 0.05). Stepwise multiple linear regression showed that only higher prephysical training concentrations of fibrinogen, PAI-1, and D-dimer explained significant proportions of the variation in changes in these variables.

CONCLUSIONS

In obese children, 4-mo periods of physical training did not lead to significant changes in hemostatic variables. Children with greater adiposity and concentrations of hemostatic factors before physical training showed greater reductions in hemostatic variables after physical training than did children with lesser values.