Plasmin generation and fibrinolysis in pediatric patients undergoing cardiopulmonary bypass surgery.

This prospective, single-centre cohort study aimed to evaluate plasmin generation and fibrinolysis during and after cardiopulmonary bypass (CPB) surgery in a cohort of children up to 6 years of age. Blood samples were drawn at eight time points: after induction of anesthesia, before unfractionated heparin (UFH), after UFH, after initiation of bypass, before protamine, after protamine, after chest closure, and 6 h after chest closure. The study identified an increase in fibrinolysis during CPB and particularly up to 6 h afterward in children. This could be the mechanism for the significant bleeding events observed in this young population after CPB. This study establishes the foundation for future studies in this area, particularly those focusing on clinical outcomes after CPB surgery.

The quantitative and qualitative responses of platelets in pediatric patients undergoing cardiopulmonary bypass surgery.

This prospective, single-center study aimed to evaluate the platelet response during cardiopulmonary bypass (CPB) surgery in a large cohort of children up to 6 years of age. Blood samples were drawn at four time points: after induction of anesthesia, after initiation of the CPB, before protamine, and immediately after chest closure. The study recruited 60 children requiring CPB for surgical repair of congenital heart defects. The platelet count decreased throughout CPB surgery, but during the same period, platelet activity increased. The more pronounced decrease in platelet count observed in children younger than 1 year compared with that of children 1 to 6 years of age was not associated with an age-specific change in platelet activity. The overall increase in platelet function observed in this study could provide a mechanism that compensates for the decrease in platelet count. This study provides a new foundation for future studies investigating requirements of platelet supplementation in the setting of pediatric CPB surgery.

Hemostatic response in paediatric patients undergoing cardiopulmonary bypass surgery.

This prospective, single-center cohort study aimed to evaluate the hemostatic response during and after Cardiopulmonary Bypass (CPB) surgery in a large cohort of children up to 6 years of age. Blood samples were drawn at eight time points: post-induction of anesthesia, pre-unfractionated heparin (UFH), post-UFH, post-initiation of bypass, pre-protamine, post-protamine, post-chest-closure, and 6 h post-chest-closure. As expected, all measures of the UFH effect increased significantly post-UFH bolus and decreased post-protamine administration. However, thrombin generation remained inhibited compared to baseline values despite the post-UFH reversal by protamine. We also demonstrate that residual UFH effect is not responsible for the ongoing inhibition of thrombin observed post-protamine administration. The significant increase in both free and total tissue factor pathway inhibitor levels during the CPB surgery might contribute to the persistent thrombin generation/endogenous thrombin potential inhibition post-protamine administration. This study makes a significant and novel contribution by investigating the physiological mechanisms behind the degree of thrombin inhibition by UFH and the residual levels of thrombin inhibition that continue despite protamine reversal and provides a new foundation for future interventional studies in the setting of paediatric CPB surgery.

Monitoring Unfractionated Heparin (UFH) therapy: which Anti-Factor Xa assay is appropriate?

INTRODUCTION: Anti-Factor Xa (Anti-Xa) assays specifically determine the anticoagulant activity of UFH by measuring the ability of heparin-bound Antithrombin (AT) to inhibit a single enzyme, Factor Xa (FXa). Recent improvements in the automation, cost-effectiveness and accessibility of the assay to clinicians, have resulted in the Anti-Xa assay becoming a part of daily clinical practice in many institutions. OBJECTIVES: We hypothesized that different Anti-Xa assays have different applicability for use in clinical settings, depending on the amount of UFH administered. This was investigated in a tertiary paediatric institution. MATERIALS AND METHODS: Samples were collected from children receiving Low-dose of UFH of at least 10 IU/kg/h, with or without a previous bolus of up to 25 IU/kg/h, within the previous 6 h in the PICU and HDU. High-dose UFH population consisted of children undergoing Cardiac Catheterization (CC), who received a bolus of UFH of 100 IU/kg body weight, 30 min prior to sampling. RESULTS AND CONCLUSIONS: The Anti-Xa activity for a given dose of UFH was found to vary significantly based on the Anti-Xa assay and the population being monitored. Our study suggests that the MODIFIED COMATIC Anti-Xa assay provides the best physiological measure of the UFH effect in children, as it does not introduce sources of error, such as exogenous AT, which may increase the measured ant Factor Xa activity, nor Dextran Sulphate which can displace plasma protein bound heparin and once again leading to falsely elevated assay results. Further studies that include assessment of clinical outcomes are required to confirm the applicability of use of this particular assay in monitoring UFH therapy.