Comprehensive Characterization of Surface-Bound Proteins and Measurement of Fibrin Fiber Thickness on Extracorporeal Membrane Oxygenation Circuits Collected From Patients.

OBJECTIVE: To characterize surface-bound proteins and to measure the thickness of fibrin fibers bound to extracorporeal membrane oxygenation (ECMO) circuits used in children. DESIGN: Single-center observational prospective study, April to November 2021. SETTING: PICU, Royal Children's Hospital, Melbourne, Australia. PATIENTS: Patients aged less than 18 years on venoarterial ECMO and without preexisting disorder. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: ECMO circuits were collected from six patients. Circuit samples were collected from five different sites, and subsequently processed for proteomic and scanning electron microscopy (SEM) studies. The concentration of proteins bound to ECMO circuit samples was measured using a bicinchoninic acid protein assay, whereas characterization of the bound proteome was performed using data-independent acquisition mass spectrometry. The Reactome Over-representation Pathway Analyses tool was used to identify functional pathways related to bound proteins. For the SEM studies, ECMO circuit samples were prepared and imaged, and the thickness of bound fibrin fibers was measured using the Fiji ImageJ software, version 1.53c (https://imagej.net/software/fiji/). Protein binding to ECMO circuit samples and fibrin networks showed significant intra-circuit and interpatient variation. The median (range) total protein concentration was 19.0 (0-76.9) µg/mL, and the median total number of proteins was 2011 (1435-2777). A total of 933 proteins were commonly bound to ECMO circuit samples from all patients and were functionally involved in 212 pathways, with signal transduction, cell cycle, and metabolism of proteins being the top three pathway categories. The median intra-circuit fibrin fiber thickness was 0.20 (0.15-0.24) µm, whereas the median interpatient fibrin fiber thickness was 0.18 (0.15-0.21) µm. CONCLUSIONS: In this report, we have characterized proteins and fiber fibrin thickness bound to ECMO circuits in six children. The techniques and approaches may be useful for investigating interactions between blood, coagulation, and the ECMO circuit and have the potential for circuit design.

Clinical assessment can be lifesaving: Salvage of catastrophic cerebral ischemia by conversion to central extracorporeal membrane oxygenation.

Peripheral veno-artertial extracorporeal membrane oxygenation (VA-ECMO) is commonly used in the paediatric population for intractable respiratory and cardiac failure. One of the devastating complications of VA-ECMO is severe brain damage due to ischemia or haemorrhage. We describe a case of peripheral cervical VA-ECMO complicated by evolving right cerebral ischemia which was rescued with rapid conversion from peripheral to central VA-ECMO support. Notably, the patient had a complete circle of Willis. Following conversion, we observed complete resolution of neurological symptoms with full functional recovery.

Changes in von Willebrand Factor Multimers, Concentration, and Function During Pediatric Extracorporeal Membrane Oxygenation.

OBJECTIVES: To investigate changes in von Willebrand factor (VWF) concentration, function, and multimers during pediatric extracorporeal membrane oxygenation (ECMO) and determine whether routine monitoring of VWF during ECMO would be useful in predicting bleeding. DESIGN: Prospective observational study of pediatric ECMO patients from April 2017 to May 2019. SETTING: The PICU in a large, tertiary referral pediatric ECMO center. PATIENTS: Twenty-five neonates and children (< 18 yr) supported by venoarterial ECMO. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Arterial blood samples were collected within 24 hours pre-ECMO, daily for the first 5 days of ECMO, every second day until decannulation, and 24 hours post-ECMO. The STA R Max analyzer was used to measure VWF antigen (VWF:Ag) and ristocetin cofactor (VWF:RCo) activity. VWF collagen binding (VWF:CB) was measured using an enzyme-linked immunosorbent assay. VWF multimers were measured using the semi-automated Hydragel 11 VWF Multimer assay. Corresponding clinical data for each patient was also recorded. A total of 25 venoarterial ECMO patients were recruited (median age, 73 d; interquartile range [IQR], 3 d to 1 yr). The median ECMO duration was 4 days (IQR, 3-8 d) and 15 patients had at least one major bleed during ECMO. The percentage of high molecular weight multimers (HMWM) decreased and intermediate molecular weight multimers increased while patients were on ECMO, irrespective of a bleeding status. VWF:Ag increased and the VWF:RCo/VWF:Ag and VWF:CB/VWF:Ag ratios decreased while patients were on ECMO compared with the baseline pre-ECMO samples and healthy children. CONCLUSIONS: Neonates and children on ECMO exhibited a loss of HMWM and lower VWF:CB/VWF:Ag and VWF:RCo/VWF:Ag ratios compared with healthy children, irrespective of major bleeding occurring. Therefore, monitoring VWF during ECMO would not be useful in predicting bleeding in these patients and changes to other hemostatic factors should be investigated to further understand bleeding during ECMO.

Platelet Phenotype and Function Changes With Increasing Duration of Extracorporeal Membrane Oxygenation.

OBJECTIVES: To investigate platelet pathophysiology associated with pediatric extracorporeal membrane oxygenation (ECMO). DESIGN: Prospective observational study of neonatal and pediatric ECMO patients from September 1, 2016, to December 31, 2019. SETTING: The PICU in a large tertiary referral pediatric ECMO center. PATIENTS: Eighty-seven neonates and children (< 18 yr) supported by ECMO. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Arterial blood samples were collected on days 1, 2, and 5 of ECMO and were analyzed by whole blood flow cytometry. Corresponding clinical data for each patient was also recorded. A total of 87 patients were recruited (median age, 65 d; interquartile range [IQR], 7 d to 4 yr). The median duration of ECMO was 5 days (IQR, 3-8 d) with a median length of stay in PICU and hospital of 18 days (IQR, 10-29 d) and 35 days (IQR, 19-75 d), respectively. Forty-two patients (48%) had at least one major bleed according to a priori determined definitions, and 12 patients (14%) had at least one thrombotic event during ECMO. Platelet fibrinogen receptor expression decreased (median fluorescence intensity [MFI], 29,256 vs 26,544; p = 0.0005), while von Willebrand Factor expression increased (MFI: 7,620 vs 8,829; p = 0.0459) from day 2 to day 5 of ECMO. Platelet response to agonist, Thrombin Receptor Activator Peptide 6, also decreased from day 2 to day 5 of ECMO, as measured by binding with anti-P-selectin, PAC-1 (binds activated GPIIb/IIIa), and anti-CD63 monoclonal antibodies (P-selectin area under the curve [AUC]: 63.46 vs 42.82, respectively, p = 0.0022; PAC-1 AUC: 93.75 vs 74.46, p = 0.0191; CD63 AUC: 55.69 vs 41.76, p = 0.0020). CONCLUSIONS: The loss of platelet response over time may contribute to bleeding during ECMO. These novel insights may be useful in understanding mechanisms of bleeding in pediatric ECMO and monitoring platelet markers clinically could allow for prediction or early detection of bleeding and thrombosis.

Effect of Nitric Oxide via Cardiopulmonary Bypass on Ventilator-Free Days in Young Children Undergoing Congenital Heart Disease Surgery: The NITRIC Randomized Clinical Trial.

Importance: In children undergoing heart surgery, nitric oxide administered into the gas flow of the cardiopulmonary bypass oxygenator may reduce postoperative low cardiac output syndrome, leading to improved recovery and shorter duration of respiratory support. It remains uncertain whether nitric oxide administered into the cardiopulmonary bypass oxygenator improves ventilator-free days (days alive and free from mechanical ventilation). Objective: To determine the effect of nitric oxide applied into the cardiopulmonary bypass oxygenator vs standard care on ventilator-free days in children undergoing surgery for congenital heart disease. Design, Setting, and Participants: Double-blind, multicenter, randomized clinical trial in 6 pediatric cardiac surgical centers in Australia, New Zealand, and the Netherlands. A total of 1371 children younger than 2 years undergoing congenital heart surgery were randomized between July 2017 and April 2021, with 28-day follow-up of the last participant completed on May 24, 2021. Interventions: Patients were assigned to receive nitric oxide at 20 ppm delivered into the cardiopulmonary bypass oxygenator (n = 679) or standard care cardiopulmonary bypass without nitric oxide (n = 685). Main Outcomes and Measures: The primary end point was the number of ventilator-free days from commencement of bypass until day 28. There were 4 secondary end points including a composite of low cardiac output syndrome, extracorporeal life support, or death; length of stay in the intensive care unit; length of stay in the hospital; and postoperative troponin levels. Results: Among 1371 patients who were randomized (mean [SD] age, 21.2 [23.5] weeks; 587 girls [42.8%]), 1364 (99.5%) completed the trial. The number of ventilator-free days did not differ significantly between the nitric oxide and standard care groups, with a median of 26.6 days (IQR, 24.4 to 27.4) vs 26.4 days (IQR, 24.0 to 27.2), respectively, for an absolute difference of -0.01 days (95% CI, -0.25 to 0.22; P = .92). A total of 22.5% of the nitric oxide group and 20.9% of the standard care group developed low cardiac output syndrome within 48 hours, needed extracorporeal support within 48 hours, or died by day 28, for an adjusted odds ratio of 1.12 (95% CI, 0.85 to 1.47). Other secondary outcomes were not significantly different between the groups. Conclusions and Relevance: In children younger than 2 years undergoing cardiopulmonary bypass surgery for congenital heart disease, the use of nitric oxide via cardiopulmonary bypass did not significantly affect the number of ventilator-free days. These findings do not support the use of nitric oxide delivered into the cardiopulmonary bypass oxygenator during heart surgery. Trial Registration: anzctr.org.au Identifier: ACTRN12617000821392.

Dismal Outcomes of Second-Run Extracorporeal Life Support in the Paediatric Population.

BACKGROUND: In 2011 we reported unfavourable outcomes of second-run extracorporeal life support (ECLS) in children. We wanted to investigate whether this previous report affected our strategy and modified our long-term outcomes. METHODS: Between 1988 and 2015, 31 patients underwent a second-run ECLS. Median age at the time of first support was 9days (0-16 years). Median length of support for the first and second runs were 4.7days (0.1-10) and 3.6days (0.5-8.7) respectively, with an interval of 1.8days (0.1-66) between supports. RESULTS: There was an increasing trend in the number of patients undergoing second-run ECLS after our report: 21 patients between 1988 and mid-2010 (0.9 patients/year) and 10 between mid-2010 and 2015 (two patients/year) (p=0.06). However, among all the patients who underwent ECLS, the proportion of second-run ECLS was not different before and after 2010 (4% vs. 4.2% respectively, p=0.92). While 58% of patients (18/31) survived weaning of support, only 23% (7/31) survived to hospital discharge and 14% (5/31) were still alive after hospital discharge at a median of 6.5 years (1.2-11.6). The three patients who had positive long-term outcomes had the second-run ECLS instituted to allow for major cardiac operations. CONCLUSIONS: Compassionate use of second-run ECLS is difficult to refuse but one should be aware that its outcomes are dismal. In our centre, benefits seem to be limited to cases where the second-run ECLS allows for a major cardiac intervention.

Anticoagulation strategies and difficulties in neonatal and paediatric extracorporeal membrane oxygenation (ECMO).

OBJECTIVE: The aim of this review is to highlight an emerging problem with anticoagulation-related complications in neonatal and paediatric ECMO, to explore for flaws in the currently recommended anticoagulation management responsible for these problems and to discuss possible strategies mitigating further escalation of the issue. DATA SOURCES: Pertinent neonatal and paediatric literature on the topic of interest and international Extracorporeal Life Support Organisation (ELSO) registry data request. CONCLUSIONS: The international ELSO registry data reveals increasing rates of anticoagulation-related complications during neonatal and paediatric ECMO worldwide. The causes are multifactorial and the proposed solution to the problem is to match anticoagulation management to the pathophysiological complexity of haemostasis on ECMO.

Clinical Effects of Nitric Oxide Added to the Oxygenator of Children on Extracorporeal Membrane Oxygenation: Pre-Post Cohort Study.

Nitric oxide (NO) can be safely delivered through the sweep gas to the oxygenator of an extracorporeal membrane oxygenation (ECMO) circuit. It has theoretical benefits such as preventing platelet adhesion to surfaces, mitigating inflammatory response and protection against ischemia-reperfusion injury. In this uncontrolled before-after study of children on ECMO, the outcomes of those who received NO were compared with those who did not. Among 393 ECMO runs (from 337 patients), 192 of 393 (49%) received NO and 201 of 393 (51%) did not. The use of NO was associated with a 37% reduction in circuit change (adjusted risk ratio [aRR]: 0.63, 95% confidence interval [CI]: 0.42-0.93). The aRR (95% CI) for risk of neurologic injury was 0.72 (0.47-1.11). We observed potential heterogeneity of treatment effect for the risk of neurologic injury in children who had cardiac surgery: the risk with NO was lower in those who had cardiac surgery (aRR: 0.50, 95% CI: 0.26-0.96). There was no difference in survival between the study groups. In children managed with NO delivered through the ECMO circuit, we report a reduction in observed rate of circuit change and lower risk of neurologic injury in children who underwent cardiac surgery. Nitric oxide therapy on ECMO warrants prospective evaluation in children.

Immunofluorescence Protocol for Characterization of Platelet and Leukocyte Binding in Extracorporeal Membrane Oxygenation (ECMO) Circuits.

The continuous contact between blood and the foreign surface of the extracorporeal membrane oxygenation (ECMO) circuit contributes to hemostatic, inflammatory, and other physiological disturbances observed during ECMO. Although previous studies have extensively investigated blood samples from patients on ECMO, cell adsorption to the ECMO circuit as an additional factor that could potentially influence clinical outcomes, has largely been overlooked. Here we provide a detailed immunofluorescence (IF) protocol designed to characterize cellular binding on ECMO circuits collected from patients. Extracorporeal membrane oxygenation circuits were collected from three pediatric patients and an albumin primed-only ECMO circuit was used as control. Circuit samples from five different sites within each ECMO circuit were collected and processed for the IF protocol. CD14 and CD42a antibodies were used to identify platelets and leukocytes bound to each ECMO circuit sample and images captured using inverted fluorescence microscopy. The protocol enables the comprehensive characterization of platelet and leukocyte binding to ECMO circuits collected from patients, which could in turn extend our knowledge of the characteristics of circuit binding and may provide guidance for improved ECMO circuit design.

Extracorporeal membrane oxygenation circuitry.

The extracorporeal membrane oxygenation circuit is made of a number of components that have been customized to provide adequate tissue oxygen delivery in patients with severe cardiac and/or respiratory failure for a prolonged period of time (days to weeks). A standard extracorporeal membrane oxygenation circuit consists of a mechanical blood pump, gas-exchange device, and a heat exchanger all connected together with circuit tubing. Extracorporeal membrane oxygenation circuits can vary from simple to complex and may include a variety of blood flow and pressure monitors, continuous oxyhemoglobin saturation monitors, circuit access sites, and a bridge connecting the venous access and arterial infusion limbs of the circuit. Significant technical advancements have been made in the equipment available for short- and long-term extracorporeal membrane oxygenation applications. Contemporary extracorporeal membrane oxygenation circuits have greater biocompatibility and allow for more prolonged cardiopulmonary support time while minimizing the procedure-related complications of bleeding, thrombosis, and other physiologic derangements, which were so common with the early application of extracorporeal membrane oxygenation. Modern era extracorporeal membrane oxygenation circuitry and components are simpler, safer, more compact, and can be used across a wide variety of patient sizes from neonates to adults.

The Evolution of Extracorporeal Membrane Oxygenation Circuitry and Impact on Clinical Outcomes in Children: A Systematic Review.

This systematic review summarizes the major developments in extracorporeal membrane oxygenation (ECMO) circuitry in pediatrics over the past 20 years and demonstrates the impacts of those developments on clinical outcomes. This systematic review followed structured Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A total of 1987 studies were retrieved, of which 82 were included in the final analysis. Over the past 20 years, ECMO pumps have shifted from roller pumps to centrifugal pumps. Silicone and polypropylene hollow fiber membrane oxygenators were initially used but have been replaced by polymethylpentene hollow fiber membrane oxygenators, with other ECMO components poorly reported. Considerable variability in mortality was found across studies and there was no statistical difference in mortality rates across different periods. The duration of ECMO and other outcome measures were inconsistently reported across studies. This systematic review demonstrated technological developments in pumps and oxygenators over the last two decades, although patient mortality rates remained unchanged. This could be because of ECMO support applied to patients in more critical conditions over the years. We also highlighted the limitations of methodology information disclosure and outcome measures in current ECMO studies, showing the need of reporting standardization for future ECMO studies.

Safety and feasibility of adjunct autologous cord blood stem cell therapy during the Norwood heart operation.

BACKGROUND: We conducted this phase I, open-label safety and feasibility trial of autologous cord blood (CB) stem cell (CBSC) therapy via a novel blood cardioplegia-based intracoronary infusion technique during the Norwood procedure in neonates with an antenatal diagnosis of hypoplastic left heart syndrome (HLHS). CBSC therapy may support early cardiac remodeling with enhancement of right ventricle (RV) function during the critical interstage period. METHODS: Clinical grade CB mononucleated cells (CBMNCs) were processed to NetCord-FACT International Standards. To maximize yield, CBSCs were not isolated from CBMNCs. CBMNCs were stored at 4 °C (no cryopreservation) for use within 3 days and delivered after each cardioplegia dose (4 × 15 mL). RESULTS: Of 16 patients with antenatal diagnosis, 13 were recruited; of these 13 patients, 3 were not treated due to placental abruption (n = 1) or conditions delaying the Norwood for >4 days (n = 2) and 10 received 644.9 ± 134 × 106 CBMNCs, representing 1.5 ± 1.1 × 106 (CD34+) CBSCs. Interstage mortality was 30% (n = 3; on days 7, 25, and 62). None of the 36 serious adverse events (53% linked to 3 deaths) were related to CBMNC therapy. Cardiac magnetic resonance imaging before stage 2 (n = 5) found an RV mass index comparable to that in an exact-matched historical cohort (n = 22), with a mean RV ejection fraction of 66.2 ± 4.5% and mean indexed stroke volume of 47.4 ± 6.2 mL/m2 versus 53.5 ± 11.6% and 37.2 ± 10.3 mL/m2, respectively. All 7 survivors completed stage 2 and are alive with normal RV function (6 with ≤mild and 1 with moderate tricuspid regurgitation). CONCLUSIONS: This trial demonstrated that autologous CBMNCs delivered in large numbers without prior cryopreservation via a novel intracoronary infusion technique at cardioplegic arrest during Norwood palliation on days 2 to 3 of life is feasible and safe.

Factors XI and XII in extracorporeal membrane oxygenation: longitudinal profile in children.

Background: Extracorporeal membrane oxygenation (ECMO) is used in children with cardiopulmonary failure. While the majority of ECMO centers use unfractionated heparin, other anticoagulants, including factor XI and factor XII inhibitors are emerging, which may prove suitable for ECMO patients. However, before these anticoagulants can be applied in these patients, baseline data of FXI and FXII changes need to be acquired. Objectives: This study aimed to describe the longitudinal profile of FXI and FXII antigenic levels and function before, during, and after ECMO in children. Methods: This is a prospective observational study in neonatal and pediatric patients with ECMO (<18 years). All patients with venoarterial ECMO and with sufficient plasma volume collected before ECMO, on day 1 and day 3, and 24 hours postdecannulation were included. Antigenic levels and functional activity of FXI and FXII were determined in these samples. Longitudinal profiles of these values were created using a linear mixed model. Results: Sixteen patients were included in this study. Mean FXI and FXII antigenic levels (U/mL) changed from 7.9 and 53.2 before ECMO to 6.0 and 34.5 on day 3 and they recovered to 8.8 and 39.4, respectively, after stopping ECMO. Function (%) of FXI and FXII decreased from 59.1 and 59.0 to 49.0 and 50.7 on day 3 and recovered to 66.0 and 54.4, respectively. Conclusion: This study provides the first insights into changes of the contact pathway in children undergoing ECMO. FXI and FXII antigen and function change during ECMO. Results from this study can be used as starting point for future contact pathway anticoagulant studies in pediatric patients with ECMO.

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.

Statistical analysis plan for the NITric oxide during cardiopulmonary bypass to improve Recovery in Infants with Congenital heart defects (NITRIC) trial.

Background: The NITric oxide during cardiopulmonary bypass (CPB) to improve Recovery in Infants with Congenital heart defects (NITRIC) trial, a 1320-patient, multicentre, randomised controlled trial, is aiming to improve survival free of ventilation after CPB by using nitric oxide delivered into the oxygenator of the CPB. Objective: To provide a statistical analysis plan before completion of patient recruitment and data monitoring. Final analyses for this study will adhere to this statistical analysis plan, which details all key pre-planned analyses. Stata scripts for analyses have been prepared alongside this statistical analysis plan. Methods: The statistical analysis plan was designed collaboratively by the chief investigators and trial statistician and builds on the previously published study protocol. All authors remain blinded to treatment allocation. Detail is provided on statistical analyses including cohort description, analysis of primary and secondary outcomes and adverse events. Statistical methods to compare outcomes are planned in detail to ensure methods are verifiable and reproducible. Results: The statistical analysis plan developed provides the trial outline, list of mock tables, and analysis scripts. The plan describes statistical analyses on cohort and baseline description, primary and secondary outcome analyses, process of care measures, physiological descriptors, and safety and adverse event reporting. We define the pre-specified subgroup analyses and the respective statistical tests used to compare subgroups. Conclusion: The statistical analysis plan for the NITRIC trial establishes detailed pre-planned analyses alongside Stata scripts to analyse the largest trial in the field of neonatal and paediatric heart surgery. The plan ensures standards for trial analysis validity aiming to minimise bias of analyses. Trial registration: ACTRN12617000821392.

Centrifugal pump inlet pressure site affects measurement.

During extracorporeal life support (ECLS), blood is exposed to a myriad of unphysiological factors that can affect outcome. One aspect of this is the sub-atmospheric pressure generated by the ECLS pump and imparted to blood elements along the pump inlet line. This pressure can be measured on the inlet line close to the pump head by adding a connector, or at the venous cannula connection site. We compared the two measurement sites located at both points; between the venous cannula-inlet tubing and inlet tubing-pump, with a range of cannulae and flows. We also investigated the effects on inlet pressure from pump afterload and increasing inlet tubing length.

Study protocol: NITric oxide during cardiopulmonary bypass to improve Recovery in Infants with Congenital heart defects (NITRIC trial): a randomised controlled trial.

INTRODUCTION: Congenital heart disease (CHD) is a major cause of infant mortality. Many infants with CHD require corrective surgery with most operations requiring cardiopulmonary bypass (CPB). CPB triggers a systemic inflammatory response which is associated with low cardiac output syndrome (LCOS), postoperative morbidity and mortality. Delivery of nitric oxide (NO) into CPB circuits can provide myocardial protection and reduce bypass-induced inflammation, leading to less LCOS and improved recovery. We hypothesised that using NO during CPB increases ventilator-free days (VFD) (the number of days patients spend alive and free from invasive mechanical ventilation up until day 28) compared with standard care. Here, we describe the NITRIC trial protocol. METHODS AND ANALYSIS: The NITRIC trial is a randomised, double-blind, controlled, parallel-group, two-sided superiority trial to be conducted in six paediatric cardiac surgical centres. One thousand three-hundred and twenty infants <2 years of age undergoing cardiac surgery with CPB will be randomly assigned to NO at 20 ppm administered into the CPB oxygenator for the duration of CPB or standard care (no NO) in a 1:1 ratio with stratification by age (<6 and ≥6 weeks), single ventricle physiology (Y/N) and study centre. The primary outcome will be VFD to day 28. Secondary outcomes include a composite of LCOS, need for extracorporeal membrane oxygenation or death within 28 days of surgery; length of stay in intensive care and in hospital; and, healthcare costs. Analyses will be conducted on an intention-to-treat basis. Preplanned secondary analyses will investigate the impact of NO on host inflammatory profiles postsurgery. ETHICS AND DISSEMINATION: The study has ethical approval (HREC/17/QRCH/43, dated 26 April 2017), is registered in the Australian New Zealand Clinical Trials Registry (ACTRN12617000821392) and commenced recruitment in July 2017. The primary manuscript will be submitted for publication in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: ACTRN12617000821392.

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.

Reference values for kaolin-activated thromboelastography in healthy children.

BACKGROUND: The hemostatic system of children changes with age and differs significantly from the hemostatic system of adults. Age-specific reference values are therefore required for most hemostatic variables. Thromboelastography (TEG) is a point-of-care coagulation test that may provide superior evaluation and management of coagulopathies after cardiac surgery, when large-dose unfractionated heparin is administered for cardiopulmonary bypass. In this study, we established reference values for kaolin-activated TEG in healthy children, to facilitate accurate interpretation of pediatric TEG results. METHODS: Kaolin-activated TEG was performed on 100 healthy children undergoing elective day surgery and 25 healthy adult volunteers. The following TEG variables were recorded: reaction time, coagulation time, alpha angle, maximum amplitude, percentage lysis 30 min after maximum amplitude was reached, and the coagulation index. Differences between age-groups were evaluated using analysis of variance. RESULTS: Age-specific reference values for kaolin-activated TEG in healthy children between 1 mo and 16 yr of age are presented. No significant differences between children and adults were observed. CONCLUSIONS: TEG results, from a particular clinical setting, must be compared to age-specific, as well as analyzer- and activator-specific, reference values to allow for correct interpretation of the results. Reference values provided here will be of use in acute clinical situations where a practical monitor of hemostasis is required.