Antithrombin III supplementation on extracorporeal membrane oxygenation: impact on heparin dose and circuit life

Recommendations on Monitoring and Replacement of Antithrombin, Fibrinogen, and Von Willebrand Factor in Pediatric Patients on Extracorporeal Membrane Oxygenation: The Pediatric Extracorporeal Membrane Oxygenation Anticoagulation CollaborativE Consensus Conference

OBJECTIVES

To derive systematic review informed, modified Delphi consensus regarding monitoring and replacement of specific coagulation factors during pediatric extracorporeal membrane oxygenation (ECMO) support for the Pediatric ECMO Anticoagulation CollaborativE.

DATA SOURCES

A structured literature search was performed using PubMed, Embase, and Cochrane Library (CENTRAL) databases from January 1988 to May 2020, with an update in May 2021.

STUDY SELECTION

Included studies assessed monitoring and replacement of antithrombin, fibrinogen, and von Willebrand factor in pediatric ECMO support.

DATA EXTRACTION

Two authors reviewed all citations independently, with conflicts resolved by a third reviewer if required. Twenty-nine references were used for data extraction and informed recommendations. Evidence tables were constructed using a standardized data extraction form.

DATA SYNTHESIS

Risk of bias was assessed using the Quality in Prognosis Studies tool. The evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation system. A panel of 48 experts met over 2 years to develop evidence-based recommendations and, when evidence was lacking, expert-based consensus statements. A web-based modified Delphi process was used to build consensus via the Research And Development/University of California Appropriateness Method. Consensus was defined as greater than 80% agreement. We developed one weak recommendation and four expert consensus statements.

CONCLUSIONS

There is insufficient evidence to formulate recommendations on monitoring and replacement of antithrombin, fibrinogen, and von Willebrand factor in pediatric patients on ECMO. Optimal monitoring and parameters for replacement of key hemostasis parameters is largely unknown.

Priorities for Clinical Research in Pediatric Extracorporeal Membrane Oxygenation Anticoagulation From the Pediatric Extracorporeal Membrane Oxygenation Anticoagulation CollaborativE Consensus Conference

OBJECTIVES

To identify and prioritize research questions for anticoagulation and hemostasis management of neonates and children supported with extracorporeal membrane oxygenation (ECMO) from the Pediatric ECMO Anticoagulation CollaborativE (PEACE) consensus.

DATA SOURCES

Systematic review was performed using PubMed, EMBASE, and Cochrane Library (CENTRAL) databases from January 1988 to May 2021, followed by serial consensus conferences of international, interprofessional experts in the management of ECMO for critically ill neonates and children.

STUDY SELECTION

The management of ECMO anticoagulation for critically ill neonates and children.

DATA EXTRACTION

Within each of the eight subgroups, two authors reviewed all citations independently, with a third independent reviewer resolving any conflicts.

DATA SYNTHESIS

Following the systematic review of MEDLINE, EMBASE, and Cochrane Library databases from January 1988 to May 2021, and the consensus process for clinical recommendations and consensus statements, PEACE panel experts constructed research priorities using the Child Health and Nutrition Research Initiative methodology. Twenty research topics were prioritized, falling within five domains (definitions and outcomes, therapeutics, anticoagulant monitoring, protocolized management, and impact of the ECMO circuit and its components on hemostasis).

CONCLUSIONS

We present the research priorities identified by the PEACE expert panel after a systematic review of existing evidence informing clinical care of neonates and children managed with ECMO. More research is required within the five identified domains to ultimately inform and improve the care of this vulnerable population.

Antithrombin during veno-venous extracorporeal membrane oxygenation with heparin anticoagulation: A single-center cohort study

INTRODUCTION

Antithrombin (AT) is a natural anticoagulant essential to enhancing the unfractionated heparin (UFH) anticoagulant effect. Its supplementation in the management of UFH-based anticoagulation during veno-venous extracorporeal membrane oxygenation (VV ECMO) has a strong pathophysiological rationale.

METHODS

This is a single-center, retrospective cohort study of adult VV ECMO patients with anticoagulation maintained by UFH targeting an activated partial thromboplastin time (aPTT) of 40-50 s and AT activity >80%. We compare anticoagulation management and survival outcomes between AT subpopulations, defined by a threshold AT activity ≥80%. Linear and logistic regression analyses were used to evaluate the variation in AT activity and its association with ICU survival.

RESULTS

In 244 patients enrolled from 2009 to 2022, anticoagulation was maintained by a median heparin dose of 11.4 IU/kg/h [IQR: 8.2-14.7] with a mean aPTT of 46.1 s (±7.3) and AT activity of 88.9% (±17.0). A lower mean aPTT, higher dose of UFH and shorter fraction of time without UFH were associated with higher AT activity (p < .01). Higher AT activity showed a consistent association with ICU survival (for 10% increase of AT, odds ratio for ICU mortality: 0.95; 95% CI 0.93-0.97; p value <.01).

CONCLUSIONS

There is a positive association between AT activity and UFH requirements but no significant difference in the rate of bleeding events. A higher mean AT during VV ECMO was associated with ICU survival. Future studies are needed to differentiate between exogenously supplemented versus endogenous AT effect.

Antithrombin III supplementation during neonatal and pediatric extracorporeal membrane oxygenation

BACKGROUND

Bleeding and thrombosis are common extracorporeal membrane oxygenation (ECMO) complications associated with increased mortality. Heparin is the most commonly used ECMO anticoagulant, employed in 94% of cases. Reduced antithrombin III (AT3) levels could decrease heparin effectiveness. Neonates have inherently lower levels of AT3 than adults, and pediatric patients on ECMO can develop AT3 deficiency. One potential approach for patients on ECMO with AT3 deficiency is exogenous AT3 supplementation. However, there is conflicting data concerning the use of AT3 for pediatric and neonatal patients on ECMO.

METHODS

We analyzed the Bleeding and Thrombosis during ECMO database of 514 neonatal and pediatric patients on ECMO. We constructed daily regression models to determine the association between AT3 supplementation and rates of bleeding and thrombosis. Given the physiological differences between pediatric patients and neonates, we constructed separate models for each.

RESULTS

AT3 administration was associated with increased rates of daily bleeding among pediatric (adjusted odds ratio [aOR] 1.59, p < 0.01) and neonatal (aOR 1.37, p = 0.04) patients. AT3 supplementation did not reduce the rate of thrombosis for either pediatric or neonatal patients.

CONCLUSION

AT3 administration was associated with increased rates of daily bleeding, a hypothesized potential complication of AT3 supplementation. In addition, AT3 supplementation did not result in lower rates of thrombosis. We recommend clinicians utilize caution when considering supplementing patients on ECMO with exogenous AT3.

Bivalirudin or heparin for systemic anticoagulation during pediatric extracorporeal membrane oxygenation: Multicenter retrospective study

BACKGROUND

The objective of this study is to evaluate the outcomes of unfractionated heparin (UFH) compared to bivalirudin anticoagulation in pediatric ExtraCorporeal Membrane Oxygenation (ECMO).

METHODS

A multicenter retrospective study, that included pediatric patients <18 years of age, who were supported on ECMO between June 2017 and May 2020. Patients treated with UFH were matched 2:1 by age and type of ECMO support to the bivalirudin group.

RESULTS

The bivalirudin group (75 patients) were matched to 150 patients treated with UFH. Baseline characteristics and comorbidities of the two groups were similar. Veno-Arterial ECMO was the most common mode (141/225 [63 %]) followed by extracorporeal cardiopulmonary resuscitation (48/225 [21 %]). Bivalirudin treatment was associated with lower odds of bleeding events (aOR 0.23, 95%CI 0.12-0.45, p < 0.001) and lower odds of thrombotic events (aOR 0.48, 95%CI 0.23-0.98, p = 0.045). Patients who received bivalirudin had lesser odds for transfusion with fresh frozen plasma, and platelets (aOR 0.26, CI 0.12-0.57, p ≤0.001 and aOR 0.28, CI 0.15-0.53, p < 0.001, respectively). After adjusting for the type of ECMO support and adjusting for age, bivalirudin was associated with a decrease in hospital mortality by 50 % compared to the UFH group (aOR 0.50, 95%CI 0.27-0.93, p = 0.028). Similarly, for neurological disability at time of discharge, bivalirudin was associated with higher odds of intact neurological outcomes compared to UFH (OR 1.99 [95%CI 1.13-3.51], p = 0.017).

CONCLUSIONS

This study demonstrated that effective anticoagulation can be achieved with bivalirudin, which was associated with lesser odds of bleeding events and utilization of blood products. Bivalirudin, in comparison with UFH, was associated with greater odds of hospital survival and intact neurological function at the time of discharge. A prospective randomized trial is required to validate the results of this study.

Haematological Trends and Transfusion during Adult Extracorporeal Membrane Oxygenation: A Single Centre Study

The temporal trends in haematological parameters and their associations with blood product transfusion requirements in patients supported with extracorporeal membrane oxygenation (ECMO) are poorly understood. We performed a retrospective data analysis to better understand the behaviour of haematological and coagulation parameters and their associations with transfusion requirements during ECMO.

METHODS

Patient demographics, haematological and coagulation parameters, plasma haemoglobin and fibrinogen concentrations, platelet count, the international normalised ratio (INR), the activated partial thromboplastin time (APTT), and blood product transfusion data from 138 patients who received ECMO in a single high-volume centre were analysed.

RESULTS

Ninety-two patients received venoarterial (VA) ECMO and 46 patients received venovenous (VV) ECMO. The median (IQR) duration of VA, and VV ECMO was 8 (5-13) days and 13 (8-23) days, respectively. There were significant reductions in haemoglobin, the platelet count, and the fibrinogen concentration upon initiation of ECMO. On average, over time, patients on VV ECMO had platelet counts 44 × 109/L higher than those on VA ECMO (p ≤ 0.001). Fibrinogen and APTT did not vary significantly based on the mode of ECMO (p = 0.55 and p = 0.072, respectively). A platelet count < 50 × 109/L or a fibrinogen level < 1.8 g/L was associated with 50% chance of PRBC transfusion, regardless of the ECMO type, and packed red blood cell (PRBC) transfusion was more common with VA ECMO. APTT was predictive of the transfusion requirement, and the decrement in APTT was discriminatory between VVECMO survivors and nonsurvivors.

CONCLUSION

ECMO support is associated with reductions in haemoglobin, platelet count, and fibrinogen. Patients supported with VA ECMO are more likely to receive a PRBC transfusion compared to those on VV ECMO. Thrombocytopaenia, hypofibrinogenaemia, and anticoagulation effect the likelihood of requiring PRBC transfusion. Further research is needed to define optimal blood management during ECMO, including appropriate transfusion triggers and the anticoagulation intensity.

Evaluation of acquired antithrombin deficiency in paediatric patients supported on extracorporeal membrane oxygenation

AIMS

There remains a paucity of literature regarding best practice for antithrombin (AT) monitoring, dosing and dose-response in paediatric extracorporeal membrane oxygenation (ECMO) patients.

METHODS

We conducted a retrospective cohort study at a quaternary care paediatric intensive care unit in all patients <18 years of age supported on ECMO from 1 June 2011 to 30 April 2020. Adverse events and outcomes were characterized for all ECMO runs. AT activity and replacement were characterized and compared between two clinical protocols. AT activities measured post- vs. pre-AT replacement were compared in order to characterize a dose-response relationship.

RESULTS

The final cohort included 191 patients with 201 ECMO runs and 2028 AT activity measurements. The median AT activity was 65% (interquartile range [IQR], 51-82) and 879 (43.3%) measurements met the criteria of deficient. The overall median AT dose and increase in AT activity were 50.6 units/kg/dose (IQR, 39.5-67.2) and 23.5% (IQR, 9.8-36.0), respectively. In the protocol that restricted AT activity measurements to clinical scenarios concerning for heparin resistance, there was significantly higher dosing in conjunction with significantly fewer overall administrations. Approximately one third of AT activity remained deficient after repletion. There was no difference in mechanical complications, reasons for discontinuation of ECMO support, time on ECMO or survival between protocols.

CONCLUSIONS

There was a high prevalence of AT deficiency in paediatric ECMO patients. An AT replacement protocol based on evaluating heparin resistance is associated with fewer AT administrations, with similar circuit and patient outcomes. Further data are needed to identify optimal dosing strategies.

Evaluation of a Multimodal Heparin Laboratory Monitoring Protocol in Adult Extracorporeal Membrane Oxygenation Patients

BACKGROUND

Anticoagulation monitoring practices vary during extracorporeal membrane oxygenation (ECMO). The Extracorporeal Life Support Organization describes that a multimodal approach is needed to overcome assay limitations and minimize complications.

OBJECTIVE

Compare activated clotting time (ACT) versus multimodal approach (activated partial thromboplastin time (aPTT)/anti-factor Xa) for unfractionated heparin (UFH) monitoring in adult ECMO patients.

METHODS

We conducted a single-center retrospective pre- (ACT) versus post-implementation (multimodal approach) study. The incidence of major bleeding and thrombosis, blood product and antithrombin III (ATIII) administration, and UFH infusion rates were compared.

RESULTS

Incidence of major bleeding (69.2% versus 62.2%, p = 0.345) and thrombosis (23% versus 14.9%, p = 0.369) was similar between groups. Median number of ATIII doses was reduced in the multimodal group (1.0 [IQR 0.0-2.0] versus 0.0 [0.0 -1.0], p = 0.007). The median UFH infusion rate was higher in the ACT group, but not significant (16.9 [IQR 9.6-22.4] versus 13 [IQR 9.6-15.4] units/kg/hr, p = 0.063). Fewer UFH infusion rate changes occurred prior to steady state in the multimodal group (0.9 [IQR 0.3 -1.7] versus 0.1 [IQR 0.0-0.2], p < 0.001).

CONCLUSION

The incidence of major bleeding and thrombosis was similar between groups. Our multimodal monitoring protocol standardized UFH infusion administration and reduced ATIII administration.

Anticoagulation in adult patients supported with extracorporeal membrane oxygenation: guidance from the Scientific and Standardization Committees on Perioperative and Critical Care Haemostasis and Thrombosis of the International Society on Thrombosis and Haemostasis

Anticoagulation of patients supported by extracorporeal membrane oxygenation is challenging because of a high risk of both bleeding and thrombotic complications, and often empirical. Practice in anticoagulation management is therefore highly variable. The scope of this guidance document is to provide clinicians with practical advice on the choice of an anticoagulant agent, dosing, and the optimal anticoagulant monitoring strategy during extracorporeal membrane oxygenation support in adult patients.

Pediatric Extracorporeal Membrane Oxygenation Anticoagulation Protocol Associated with a Decrease in Complications

Extracorporeal membrane oxygenation (ECMO) in pediatrics has rapidly progressed in recent years; however, there continues to be considerable variation in anticoagulation practices. In 2016, we implemented a standardized anticoagulation protocol in effort to reduce clotting and bleeding complications. A single-center retrospective analysis of pediatric patients requiring ECMO between 2014 and 2018 was performed. One hundred one ECMO cases in 94 pediatric patients met eligibility criteria (preprotocol = 64 cases; postprotocol = 37 cases). Demographics, ECMO parameters, complications, laboratories, and blood product requirements were analyzed for differences between the two groups. There was a significant decrease in the incidence of hematologic (p < 0.022), neurologic (p < 0.001), and renal complications (p < 0.001) in the postprotocol era. Incidence of bleeding, cardiac/pulmonary complications, and circuit changes were similar between the groups. The postprotocol group required fewer transfusions of red blood cells and cryoprecipitate. Additionally, platelet counts and fibrinogen levels were maintained higher in the postprotocol era. In conclusion, implementation of a standardized anticoagulation protocol was associated with improved anticoagulation parameters and a decrease in hematologic and neurologic complications, coagulopathy, renal injury, and blood product administration. We attribute these findings to transitioning to anti-Xa as a measure of heparinization and maintaining higher platelet counts.

Bivalirudin versus Heparin in Pediatric and Adult Patients on Extracorporeal Membrane Oxygenation: A Meta-analysis

AIMS

Unfractionated heparin (UFH) has been the primary anticoagulant of choice on extracorporeal membrane oxygenation (ECMO). However, it is debatable whether bivalirudin (BIV), a direct thrombin inhibitor, may be considered a better alternative anticoagulant option.

METHODS

We searched Embase, Pubmed, Cochrane library, Clinicaltrials.gov, CNKI, and Wanfang databases up to June 15, 2021. Randomized controlled trials (RCTs) and observational studies were considered eligible for inclusion. Random-effects meta-analyses, including subgroup analyses, were conducted.

RESULTS

A total of 9 studies containing 994 patients were enrolled. All articles were retrospective cohort studies. Compared with UFH, BIV was associated with lower risks of major bleeding (risk ratio [RR]: 0.32, 95% confidence interval [CI] 0.22-0.49), ECMO in-circuit thrombosis (RR: 0.57, 95% CI 0.43-0.74), stroke (RR: 0.52, 95% CI 0.29-0.95), in-hospital mortality (RR: 0.82, 95% CI 0.69-0.99) and higher rates of survival to ECMO decannulation (RR: 1.18, 95% CI 1.03-1.34). Pooled risk estimates did not show a significant association with clinical thrombotic events (RR: 0.69, 95% CI 0.45-1.07). Moreover, BIV was associated with a lower risk of ECMO in-circuit thrombosis and in-hospital mortality in the adult subgroup but not in the pediatric subgroup. However, leave-one-out sensitivity analyses indicated that the results of stroke, survival to ECMO decannulation and in-hospital mortality should be interpreted with caution.

CONCLUSIONS

BIV appears to be a potential alternative to UFH in pediatric and adult patients requiring ECMO.

Hemostasis in neonatal ECMO

Extracorporeal membrane oxygenation (ECMO) is a life-saving support for cardio-respiratory function. Over the last 50 years, the extracorporeal field has faced huge technological progress. However, despite the improvements in technique and materials, coagulation problems are still the main contributor to morbidity and mortality of ECMO patients. Indeed, the incidence and survival rates of the main hemorrhagic and thrombotic complications in neonatal respiratory ECMO are relevant. The main culprit is related to the intrinsic nature of ECMO: the contact phase activation. The exposure of the human blood to the non-endothelial surface triggers a systemic inflammatory response syndrome, which chronically activates the thrombin generation and ultimately leads to coagulative derangements. Pre-existing illness-related hemostatic dysfunction and the peculiarity of the neonatal clotting balance further complicate the picture. Systemic anticoagulation is the management's mainstay, aiming to prevent thrombosis within the circuit and bleeding complications in the patient. Although other agents (i.e., direct thrombin inhibitors) have been recently introduced, unfractionated heparin (UFH) is the standard of care worldwide. Currently, there are multiple tests exploring ECMO-induced coagulopathy. A combination of the parameters mentioned above and the evaluation of the patient's underlying clinical context should be used to provide a goal-directed antithrombotic strategy. However, the ideal algorithm for monitoring anticoagulation is currently unknown, resulting in a large inter-institutional diagnostic variability. In this review, we face the features of the available monitoring tests and approaches, mainly focusing on the role of point-of-care (POC) viscoelastic assays in neonatal ECMO. Current gaps in knowledge and areas that warrant further study will also be addressed.

Antithrombin Dose Optimization in Extracorporeal Membrane Oxygenation in Infants

Anticoagulation in extracorporeal membrane oxygenation (ECMO) is challenging, with significant morbidity and mortality associated with thrombotic complications. Unfractionated heparin (UFH) is commonly used, which depends on native antithrombin (AT) function to exert anticoagulant effects. Antithrombin deficiency is common in infants on ECMO and replacement with AT concentrate may be warranted. However, dosing recommendations in this population are limited. We conducted a retrospective review of patients <1 year of age who received recombinant AT (ATryn) while on UFH and ECMO between January 1, 2010 and December 31, 2017. Commonly used dosing equations were assessed to determine their ability to predict postdose AT levels. Patient AT levels were compared with equation-predicted postdose AT levels to determine a correlation. A total of 102 doses in 41 patients were used for analysis. Baseline mean AT level was 43% (±13%) and mean AT doses were 134 units (±58.1 units) or 40.5 units/kg (±18.7 units/kg). Median increase in the AT level was 8% (interquartile range 2-17%) with a mean postdose level of 52.6% (±14.2%). Weight-based dosing poorly correlated with postdose AT levels (r2 = 0.082). Postdose levels were best predicted when using an equation that included desired change in the AT level from baseline, the patient's weight, and added weight from the volume of the ECMO circuit (r2 = 0.427). Prospective studies are needed to evaluate optimal dosing strategies, safety, and efficacy of AT in this population.

Neonatal coagulopathies: A review of established and emerging treatments

Despite the relative frequency of both bleeding and clotting disorders among patients treated in the neonatal intensive care unit, few clear guidelines exist for treatment of neonatal coagulopathies. The study and treatment of neonatal coagulopathies are complicated by the distinct hemostatic balance and clotting components present during this developmental stage as well as the relative scarcity of studies specific to this age group. This mini-review examines the current understanding of neonatal hemostatic balance and treatment of neonatal coagulopathies, with particular emphasis on emerging treatment methods and areas in need of further investigative efforts.

Comparison of Antithrombin III Products in Pediatric Patients Receiving Extracorporeal Membrane Oxygenation

The study investigated the safety and efficacy of two antithrombin III (ATIII) products in pediatric patients receiving extracorporeal membrane oxygenation (ECMO) by performing a retrospective analysis of patients who received either recombinant ATIII (rATIII) or human-derived ATIII (hATIII). Twenty-two patients were included in the study from January 2014 to September 2015 and all received unfractionated heparin (UFH) as anticoagulation during ECMO. In total, 86 doses of ATIII were included in the analysis in which 37 doses (43%) were rATIII and 49 doses (57%) were hATIII. Unfractionated heparin rates were also evaluated for all cases (n = 86) at 24 hours post-ATIII supplementation. The UFH rate decreased after the administration of both types of ATIII. However, neither the reduction in UFH rate between the two ATIII products (p = 0.52) nor the UFH rates pre- and post-ATIII supplementation at 24 hours (p = 0.08) reached statistical significance. There was a significant difference in cost favoring the rATIII product (p < 0.0001). An ad-hoc estimation of waste associated with ATIII supplementation showed >$100,000 in financial loss of unused drug. Future studies are warranted to evaluate the efficacy of ATIII supplementation in pediatric ECMO.

Pediatric and neonatal extracorporeal life support: current state and continuing evolution

The use of extracorporeal life support (ECLS) for the pediatric and neonatal population continues to grow. At the same time, there have been dramatic improvements in the technology and safety of ECLS that have broadened the scope of its application. This article will review the evolving landscape of ECLS, including its expanding indications and shrinking contraindications. It will also describe traditional and hybrid cannulation strategies as well as changes in circuit components such as servo regulation, non-thrombogenic surfaces, and paracorporeal lung-assist devices. Finally, it will outline the modern approach to managing a patient on ECLS, including anticoagulation, sedation, rehabilitation, nutrition, and staffing.

Anti-Xa versus time-guided anticoagulation strategies in extracorporeal membrane oxygenation: a systematic review and meta-analysis

The purpose was to compare time-based vs anti-Xa-based anticoagulation strategies in patients on ECMO. We conducted a systematic review and meta-analysis using multiple electronic databases and included studies from inception to July 19, 2019. The proportion of bleeding, thrombosis, and mortality were evaluated.

Twenty-six studies (2,086 patients) were included. Bleeding occurred in 34.2% (95%CI 25.1;43.9) of the patients with anti-Xa-based versus 41.6% (95%CI 24.9;59.4) of the patients with time-based anticoagulation strategies. Thrombosis occurred in 32.6% (95%CI 19.1;47.7) of the patients with anti-Xa-based versus 38.4% (95%CI 22.2;56.1) of the patients with time-based anticoagulation strategies. And mortality rate was 35.4% (95%CI 28.9;42.1) of the patients with anti-Xa-based versus 42.9% (95%CI 36.9;48.9) of the patients with time-based anticoagulation strategies. Among the seven studies providing results from both anticoagulation strategies, significantly fewer bleeding events occurred in the anti-Xa-based anticoagulation strategy (adjusted OR 0.49 (95%CI 0.32;0.74), p < 0.001) and a significantly lower mortality rate (adjusted OR 0.61 (95%CI 0.40;0.95), p = 0.03). There was no significant difference in thrombotic events (adjusted OR 0.91 (95%CI 0.56;1.49), p = 0.71). In these seven observational studies, only a small fraction of the patients were adults, and data were insufficient to analyze the effect of the type of ECMO.

In this meta-analysis of observational studies of patients on ECMO, an anti-Xa-based anticoagulation strategy, when compared to a time-based strategy, was associated with fewer bleeding events and mortality rate, without an increase in thrombotic events.

Antithrombin Dosing Guidelines in Children Underestimate Dose Needed for Plasma Level Increase

OBJECTIVES

Antithrombin is a cofactor in the coagulation cascade with mild anticoagulant activity and facilitates the action of heparin as an anticoagulant. Antithrombin concentrate dosing guidelines vary but most commonly suggest that each unit of antithrombin concentrate per body weight increases the plasma antithrombin level by 1.5% to 2.2% (depending on manufacturer). We aimed to establish a dosing recommendation dependent on age and disease state.

DESIGN

A retrospective analysis of all antithrombin concentrate doses over a period of 5 years. We calculated the increase any respective antithrombin concentrate dose achieved, indexed by body weight, and performed a multivariable analysis to establish independent factors associated with the effectiveness of antithrombin concentrate.

SETTING

A PICU at a university-affiliated children's hospital.

PATIENTS

One hundred fifty-five patients treated in a PICU.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The effect of 562 doses of antithrombin concentrate on plasma antithrombin levels administered to 155 patients, of which 414 (73.7%) antithrombin concentrate doses administered during extracorporeal life support treatment, were analyzed. For all patients, each unit of antithrombin concentrate/kg increased plasma antithrombin level by 0.86% (SD 0.47%). Plasma antithrombin level increase was influenced by body weight (increase of 0.76% [interquartile range, 0.6-0.92%] for patients < 5 kg; 1.38% [interquartile range, 1.11-2.10%] for > 20 kg), disease state (liver failure having the poorest antithrombin increase) and whether patients were treated with extracorporeal circulatory support (less antithrombin increase on extracorporeal life support). Heparin dose at the time of administration did not influence with amount of change in antithrombin level.

CONCLUSIONS

Current antithrombin concentrate dosing guidelines overestimate the effect on plasma antithrombin level in critically ill children. Current recommendations result in under-dosing of antithrombin concentrate administration. Age, disease state, and extracorporeal life support should be taken into consideration when administering antithrombin concentrate.

Antithrombin use during pediatric cardiac extracorporeal membrane oxygenation admission: insights from a national database

INTRODUCTION

The frequency of extracorporeal membrane oxygenation in pediatric patients continues to increase, especially in patients with complex congenital heart disease. Providing adequate anticoagulation is necessary for patients on extracorporeal membrane oxygenation and is achieved with adequate heparin administration. Antithrombin is administered to potentiate heparin's effects. However, the efficacy of antithrombin supplementation is unclear and a clear clinical benefit has not been established. We present a large retrospective study examining the effects of antithrombin on pediatric patients receiving extracorporeal membrane oxygenation.

METHODS

Data for this study were obtained from the Pediatric Health Information System and Pediatric Health Information System+ databases from 2004 to 2015. Pediatric patients receiving extracorporeal membrane oxygenation with a congenital heart disease diagnosis were included and divided into groups that did or did not utilize antithrombin. For all admissions, the following were captured: age of admission, gender, year of admission, length of stay, billed charges, inpatient mortality, the presence of specific congenital malformations of the heart, specific cardiac surgeries, and comorbidities.

RESULTS

A total of 9,193 admissions were included and 865 (9.4%) utilized antithrombin. Between groups, there were significantly different frequencies of co-morbidities, cardiac lesion types and antithrombin usage over the study period. There were significantly lower odds in the antithrombin group of venous thrombosis. Antithrombin was not significantly associated with hemorrhage; however, antithrombin was associated with increased inpatient mortality and a decrease in length of stay and billed charges.

CONCLUSION

Antithrombin administration is associated with increased mortality, a shorter length of stay, and decreased billing cost. Recently, antithrombin usage has been decreasing-potentially due to the reported lack of clinical benefit. Together, these results reinforce that antithrombin may not be indicated for all pediatric extracorporeal membrane oxygenation patients.

In-Depth Extracorporeal Cardiopulmonary Resuscitation in Adult Out-of-Hospital Cardiac Arrest

The use of extracorporeal cardiopulmonary resuscitation (E‐CPR) for the treatment of patients with out‐of‐hospital cardiac arrest who do not respond to conventional cardiopulmonary resuscitation CPR) has increased significantly in the past 10 years, in response to case reports and observational studies reporting encouraging results. However, no randomized controlled trials comparing E‐CPR with conventional CPR have been published to date. The evidence from systematic reviews of the available observational studies is conflicting. The inclusion criteria for published E‐CPR studies are variable, but most commonly include witnessed arrest, immediate bystander CPR, an initial shockable rhythm, and an estimated time from CPR start to establishment of E‐CPR (low‐flow time) of <60 minutes. A shorter low‐flow time has been consistently associated with improved survival. In an effort to reduce low‐flow times, commencement of E‐CPR in the prehospital setting has been reported and is currently under investigation. The provision of an E‐CPR service, whether hospital based or prehospital, carries considerable cost and technical challenges. Despite increased adoption, many questions remain as to which patients will derive the most benefit from E‐CPR, when and where to implement E‐CPR, optimal post‐arrest E‐CPR care, and whether this complex invasive intervention is cost‐effective. Results of ongoing trials are awaited to determine whether E‐CPR improves survival when compared with conventional CPR.

Antithrombin During Extracorporeal Membrane Oxygenation in Adults: National Survey and Retrospective Analysis

The impact of antithrombin replacement during extracorporeal membrane oxygenation (ECMO) in adults remains unclear. This work comprises a survey, showing that antithrombin is routinely supplemented in many Italian ECMO-Centers, and a retrospective analysis on 66 adults treated with veno-venous ECMO and unfractionated heparin at our Institution. Twenty-four to 72 h after the beginning of ECMO, antithrombin activity was ≤70% in 47/66 subjects and activated partial thromboplastin time (aPTT) ratio was <1.5 in 20/66 subjects. Activated partial thromboplastin time ratio <1.5 was associated not with lower antithrombin activity (61 ± 17 vs. 63 ± 22%; p = 0.983) but with higher circulating level of C-reactive protein (23 ± 8 vs. 11 ± 9 mg/dl; p < 0.001). In 34 subjects who received antithrombin concentrate, antithrombin activity increased (from 54 ± 9 to 84 ± 13%; p < 0.001); the proportion of subjects with aPTT ratio ≥1.5 increased (from 21/34 [62%] to 31/34 [91%]; p = 0.004); heparin dosage remained constant (from 19 ± 7 to 19 ± 6 IU/kg/h; p = 0.543); and C-reactive protein decreased (from 17 ± 10 to 13 ± 9 mg/dl; p = 0.013). Among those with aPTT ratio <1.5, aPTT ratio remained <1.5 in 3 out of 13 subjects. Antithrombin is frequently supplemented during veno-venous ECMO although low antithrombin activity does not constantly impede, and antithrombin replacement does not constantly ensure, reaching the target aPTT ratio. Inflammation possibly affects the individual response to heparin.

Overview of Pharmacological Considerations in Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation has become more widely used in recent years. Although this technology has proven to be lifesaving, it is not devoid of complications contributing to significant morbidity and mortality. Nurses who care for patients receiving extracorporeal membrane oxygenation should further their understanding of changes in medication profiles due to complex interactions with the extracorporeal membrane oxygenation circuitry. The aim of this comprehensive review is to give nurses a better understanding of analgesic, sedative, anti-infective, and anticoagulation medications that are frequently used to treat patients receiving extracorporeal membrane oxygenation.

Antithrombin Population Pharmacokinetics in Pediatric Ventricular Assist Device Patients

OBJECTIVES

Describe the pharmacokinetics of antithrombin in pediatric patients undergoing ventricular assist device therapy and provide dosing recommendations for antithrombin in this population.

DESIGN

A retrospective population pharmacokinetic study was designed.

SETTING

Large tertiary care children's hospital Subject inclusion criteria consisted of less than 19 years old.

PATIENTS

Subjects less than 19 years old undergoing therapy with a HeartWare ventricular assist device (HeartWare, Framingham, MA) or Berlin EXCOR ventricular assist device (Berlin GmbH, Berlin, Germany), who received a dose of antithrombin with a postdose antithrombin activity level from January 1, 2011, to June 30, 2017.

INTERVENTIONS

Population pharmacokinetic analysis and simulation using NONMEM v.7.4 (Icon, PLC, Dublin, Ireland).

MEASUREMENTS AND MAIN RESULTS

A total of 41 patients met study criteria (median age, 5.8 years [interquartile range, 1.6-9.9 yr]), and 53.7% underwent therapy with the pulsatile Berlin EXCOR pediatric ventricular assist device (Berlin Heart GmbH, Berlin, Germany). All patients received unfractionated heparin continuous infusion at a mean ± SD dose of 29 ± 14 U/kg/hr. A total of 181 antithrombin doses (44.1 ± 24.6 U/kg/dose) were included, and baseline antithrombin activity levels were 77 ± 12 U/dL. Antithrombin activity levels were drawn a median 19.9 hours (interquartile range, 8.8-41.6 hr) after antithrombin dose. A one-compartment proportional error model best fit the data, with allometric scaling of fat-free mass providing a better model fit than actual body weight. Unfractionated heparin and baseline antithrombin were identified as significant covariates. A 50 U/kg dose of antithrombin had a simulated half-life 13.2 ± 6.6 hours.

CONCLUSIONS

Antithrombin should be dosed on fat-free mass in pediatric ventricular assist device patients. Unfractionated heparin dose and baseline antithrombin activity level should be considered when dosing antithrombin in pediatric ventricular assist device patients.

Evaluation of a heparin monitoring protocol for extracorporeal membrane oxygenation and review of the literature

Background

Bleeding complications are common with extracorporeal membrane oxygenation (ECMO). We investigated whether a heparin monitoring protocol using activated partial thromboplastin time (aPTT) and thromboelastography (TEG) affected clinical outcomes.

Methods

This retrospective chart review stratified cohorts by study interval: pre-protocol (January 2016-March 2017) or post-protocol (March 2017-December 2017). The protocol defined therapeutic anticoagulation as aPTT of 60-80 seconds and a TEG reaction (TEG-R) time of 2-4× baseline; pre-protocol management used aPTT alone. The primary endpoints were the rates of bleeding and thrombotic events (clinical/device thrombosis) as defined by Extracorporeal Life Support Organization (ELSO) guidelines. Secondary endpoints included time in therapeutic aPTT range, rate of physician compliance with the protocol, time to heparin initiation, intensive care unit length of stay, mortality, and antithrombin III (ATIII) supplementation.

Results

The pre-protocol (n=72) and post-protocol (n=51) groups (age 60±12 years; 80% on venoarterial ECMO; average ECMO duration of 6 days) showed no difference in baseline characteristics. Major bleeding events occurred in 69% of pre-protocol patients, versus 67% of post-protocol patients (P=0.85). The post-protocol group had fewer retroperitoneal bleeds (P=0.01) and had a non-significantly lower rate of pulmonary or central nervous system (CNS) bleeding (P=0.07). Thrombotic events occurred in 21% of the pre-protocol group, versus 28% of the post-protocol group (P=0.39). Mortality during ECMO support was significantly lower in the post-protocol group (56.9% vs. 33.3%, P=0.01). The thrombosis rate was higher in patients who received ATIII than in those who did not (48.2% vs. 15.9%, P<0.01).

Conclusions

Major bleeding did not differ between the treatment groups. However, we observed significantly less mortality and retroperitoneal bleeding in the post-protocol group, suggesting an important gain from the intervention. Further study of the value of ATIII supplementation in ECMO patients is needed since we observed that a lower baseline ATIII level may indicate higher risk for thrombosis.

Antithrombin supplementation in adult patients receiving extracorporeal membrane oxygenation

INTRODUCTION

Extracorporeal membrane oxygenation is associated with an increased risk of thrombosis and hemorrhage. Acquired antithrombin deficiency often occurs in patients receiving extracorporeal membrane oxygenation, necessitating supplementation to restore adequate anticoagulation. Criteria for antithrombin supplementation in adult extracorporeal membrane oxygenation patients are not well defined.

METHODS

In this retrospective observational study, adult patients receiving antithrombin supplementation while supported on extracorporeal membrane oxygenation were evaluated. Antithrombin was supplemented when anti-Xa levels were subtherapeutic with unfractionated heparin infusion rates of 15-20 units/kg/h and measured antithrombin activity <50%. Patients were evaluated for changes in degree of anticoagulation and signs of bleeding 24 hours pre- and post-antithrombin supplementation.

RESULTS

A total of 14 patients received antithrombin supplementation while on extracorporeal membrane oxygenation. The median percentage of time therapeutic anti-Xa levels were maintained was 0% (0-43%) and 40% (9-84%) in the pre-antithrombin and post-antithrombin groups, respectively (p = 0.13). No difference was observed in the number of patients attaining a single therapeutic anti-Xa level (pre-antithrombin = 6, post-antithrombin = 13; p = 0.37) or unfractionated heparin infusion rate (pre-antithrombin = 7.35 (1.95-10.71) units/kg/h, post-antithrombin = 6.81 (3.45-12.58) units/kg/h; p = 0.33). Thirteen patients (92%) achieved an antithrombin activity at goal following supplementation. Antithrombin activity was maintained within goal range 52% of the time during the replacement period. Four bleeding events occurred pre-antithrombin and 10 events post-antithrombin administration (p = 0.26) with significantly more platelets administered post-antithrombin (pre-antithrombin = 0.5 units, post-antithrombin = 4.5 units; p = 0.01).

CONCLUSION

Therapeutic anticoagulation occurred more frequently following antithrombin supplementation; however, this difference was not statistically significant. More bleeding events occurred following antithrombin supplementation while observing an increase in platelet transfusions.

Antithrombin supplementation during extracorporeal membrane oxygenation: study protocol for a pilot randomized clinical trial

BACKGROUND

Normal levels of plasma antithrombin (AT) activity might decrease heparin requirements to achieve an adequate level of anticoagulation during treatment with extracorporeal membrane oxygenation (ECMO). Acquired AT deficiency during ECMO is common, but formal recommendations on target, timing, and rate of AT supplementation are lacking. Thus, we conceived a pilot trial to evaluate the feasibility and safety of prolonged AT supplementation in patients requiring veno-venous ECMO for respiratory failure.

METHODS

Grifols Antithrombin Research Awards (GATRA) is a prospective, randomized, single blinded, multicenter, controlled two-arm trial. Patients undergoing veno-venous ECMO will be randomized to either receive AT supplementation to maintain a functional AT level between 80 and 120% (AT supplementation group) or not (control group) for the entire ECMO course. In both study groups, anticoagulation will be provided with unfractionated heparin following a standardized protocol. The primary endpoint will be the dose of heparin required to maintain the ratio of activated partial thromboplastin time between 1.5 and 2. Secondary endpoints will be the adequacy of anticoagulation and the incidence of hemorrhagic and thrombotic complications.

DISCUSSION

GATRA is a pilot trial that will test the efficacy of a protocol of AT supplementation in decreasing the heparin dose and improving anticoagulation adequacy during ECMO. If positive, it might provide the basis for a future larger trial aimed at verifying the impact of AT supplementation on a composite outcome endpoint including hemorrhagic events, transfusion requirements, and mortality.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03208270 . Registered on 5 July 2017.

Right Sided Intracardiac Thrombosis during Veno-Arterial Extracorporeal Membrane Oxygenation: A Case Report and Literature Review

Veno-Arterial Extracorporeal Membrane Oxygenation is a common technology of the modern era used as a bridge in severe refractory cardiac and respiratory failure until definitive management is planned. However, early recognition and management of one of the most challenging complications, intracardiac thrombus, continue to remain a conundrum. The incidence of the clinical scenario is very rare. Therefore, due to the lack of literature, there are no guidelines for risk stratification, prevention, or management of intracardiac thrombus. We describe a case of massive pulmonary embolism, who developed a sudden right sided intra-cardiac thrombosis while being optimally anticoagulated on VA ECMO. We also review the literature to describe the pathophysiology, risk stratification, prevention, and management of this rare entity.

Traditional and non-traditional anticoagulation management during extracorporeal membrane oxygenation

Unfractionated heparin (UFH) is the anticoagulant of choice during extracorporeal membrane oxygenation (ECMO) support. Despite its favorable pharmacologic properties, management of heparin anticoagulation during ECMO remains a major challenge. To date, little is known about the optimal monitoring strategy or the heparin dose offering the best safety/efficacy profile. Therefore, it remains unclear if the heparin dose should be adapted to target a specific "clotting time" [e.g., activated clotting time (ACT) or activated partial thromboplastin time (aPTT)] or a heparin concentration, measured by coagulation factor anti-Xa assay. In addition, no study has compared the relevance of modern viscoelastic coagulation tests over the single value of a clotting time or heparin concentration value. Although guidelines for anticoagulation during ECMO support have been published, the absence of evidence limits the quality of the recommendations provided, which explains the major intra- and inter-institutional variability observed. Large prospective multicenter trials are urgently needed to investigate the optimal anticoagulation management strategy during ECMO support.

Anticoagulation during ECMO in neonatal and paediatric patients

Extracorporeal Membrane Oxygenation (ECMO) is a form of Extracorporeal Life Support (ECLS) which is used frequently in the paediatric and neonatal setting to support either the pulmonary, or both the pulmonary and cardiac systems. Management of ECMO requires the use of systemic anticoagulation to prevent patient and circuit based thrombosis, which in turn increases the risk of haemorrhage. A number of coagulation tests, laboratory and point of care based, are used to monitor anticoagulation, however the evidence for correlation of the test results with level of anticoagulant and clinical outcomes in children remains poor.

The Impact of Antithrombin III Use in Achieving Anticoagulant Goals in Pediatric Patients

OBJECTIVES

To determine the percentage of patients with >10% reduction in heparin infusion rate within 48 hours of antithrombin III (ATIII) administration. Secondary objectives include the achievement of therapeutic anticoagulation and determining the days of subtherapeutic infusion prior to supplementation.

METHODS

Retrospective chart review of 12 patients younger than 18 years of age who received ATIII concentrate supplementation while on continuous heparin infusion. Specific indications for heparin infusion therapy included extracorporeal membrane oxygenation (ECMO), treatment of thrombus, and post implantation of ventricular assist device(s).

RESULTS

From time of heparin initiation to ATIII supplementation, patients spent a mean 4.9 ± 2.6 days of subtherapeutic infusion and required uptitration from a mean of 15.3 ± 4.4 units/kg/hr to a mean rate of 40.7 ± 9.5 units/kg/hr. 58.3% of the patients (n = 7) had a ≥10% reduction from the baseline heparin infusion rate within 48 hours of ATIII administration. Those patients considered responders (≥10% reduction from baseline rate) had a slightly higher mean baseline antithrombin level (76.3% ± 22.0% vs. 58.6% ± 2.7% in non-responders, p = 0.1) and were administered comparable doses of ATIII. ATIII supplementation did appear to increase the time of therapeutic anticoagulation within the 48 hours.

CONCLUSIONS

Administration of ATIII is associated with >10% decrease in heparin requirements in more than half of the patients identified. In those patients deemed non-responders, there was a trend towards lower baseline antithrombin serum levels. Further studies are warranted to determine if the lack of response in some patients is due to inadequate dosing of ATIII or any patient-related factors.

Population pharmacokinetics of human antithrombin concentrate in paediatric patients

AIMS

Antithrombin is increasingly used in paediatric patients, yet there are few age-specific pharmacokinetic data to guide dosing. We aimed to describe the pharmacokinetic profile of human (plasma-derived) antithrombin concentrate in paediatric patients.

METHODS

A 5-year retrospective review was performed of patients <19 years of age admitted to our institution who received antithrombin concentrate, were not on mechanical circulatory support and had baseline (predose) and postdose plasma antithrombin activity levels available for analysis. Demographic and laboratory variables, antithrombin dosing information and data on the use of continuous infusion unfractionated heparin were collected. Population pharmacokinetic analysis was performed with bootstrap analysis. The model developed was tested against a validation dataset from a cohort of similar patients, and a predictive value was calculated.

RESULTS

A total 184 patients met the study criteria {46.7% male, median age [years] 0.35 [interquartile range (IQR) 0.07-3.9]}. A median of two antithrombin doses (IQR 1-4) were given to patients (at a dose of 46.3 ± 13.6 units kg^-1 ), with median of three (IQR 2-7) postdose levels per patient. Continuous infusion unfractionated heparin was administered in 87.5% of patients, at a mean dose of 34.1 ± 22.7 units kg^-1 h^-1 . A one-compartment exponential error model best fit the data, and significant covariates included allometrically scaled weight on clearance and volume of distribution, unfractionated heparin dose on clearance, and baseline antithrombin activity level on volume of distribution. The model resulted in a median -1.75% prediction error (IQR -11.75% to 6.5%) when applied to the validation dataset (n = 30).

CONCLUSIONS

Antithrombin pharmacokinetics are significantly influenced by the concurrent use of unfractionated heparin and baseline antithrombin activity.

Pediatric Extracorporeal Membrane Oxygenation

Extracorporeal life support is a modified form of cardiopulmonary bypass. Experience in extracorporeal membrane oxygenation (ECMO) has come largely from the neonatal population. Most centers have transitioned the ECMO pumps from roller pumps to centrifugal technology. Modes of support include venovenous for respiratory support and venoarterial for cardiac support. "Awake" ECMO is the trend with extubation and tracheostomy on the rise. Fluid overload is common and managed with diuretics or hemofiltration. Nutrition is important and provided enterally or via total parenteral nutrition. Overall survival for pediatric cardiac and respiratory ECMO has remained at approximately 50% to 60%.

Outcomes following routine antithrombin III replacement during neonatal extracorporeal membrane oxygenation

BACKGROUND

We sought to examine the effect of routine antithrombin III (AT3) infusion on hemorrhagic and thrombotic complications, blood product utilization, and circuit lifespan in neonatal extracorporeal membrane oxygenation (ECMO).

METHODS

We performed a retrospective cohort study of 162 infants placed on ECMO for hypoxic respiratory failure. Infants requiring ECMO for primary cardiac support were excluded. Demographic data, time on ECMO, blood product usage, coagulation profile, and complications were compared between 90 control patients and 72 patients treated with AT3.

RESULTS

Infants receiving AT3 during ECMO had less thrombotic and similar bleeding complications as compared to infants receiving standard anticoagulation therapy. Total blood product infusion during ECMO was decreased (54.7±20.1 vs. 67.4±34.9mL/kg per day, p=0.001) in infants receiving AT3 during ECMO. Tighter control of activated clotting time and higher serum heparin anti-Xa levels were observed in the AT3 cohort during the first days of ECMO support. 1st ECMO circuit lifespan did not differ between groups.

CONCLUSIONS

Routine administration of AT3 in neonates receiving ECMO therapy was associated with tighter control of anticoagulation and a reduction in thrombotic events without increasing unwanted bleeding. However, circuit lifespan was unaffected.

LEVEL OF EVIDENCE

Level III.

Considerations for analgosedation and antithrombotic management during extracorporeal life support

Despite the immense growth in extracorporeal life support (ECLS) technology and experience, opportunity remains to better characterize the pharmacotherapeutic considerations during ECLS. Analgosedation can be particularly challenging in the ECLS population due to in drug-circuit interactions that may lead to decreased systemic concentrations and pharmacodynamic effect. ECLS also requires the use of antithrombotic agents to mitigate the prothrombotic state created by the artificial surface in the ECLS circuit. There are a number of coagulation monitoring tests available. However, optimal monitoring and management in ECLS has not been established. Heparin continues to be the anticoagulant of choice for most ECLS centers, however, there is growing interest in the use of parenteral direct thrombin inhibitors (DTI) in this population. Advances in understanding pharmacotherapeutic management have not kept up with the technological advances in this population. More investigation is warranted to gain a greater understanding of the pharmacotherapeutic implications, facilitate standardized evidence-based practices, and improve patient centered outcomes.

Antithrombin III Doses Rounded to Available Vial Sizes in Critically Ill Pediatric Patients

OBJECTIVES

Children have decreased levels of antithrombin III (AT III) compared to adults. These levels may be further decreased during acute illness. Administration of exogenous AT III can increase anticoagulant efficacy. The objective of this study was to evaluate AT III doses rounded to available vial sizes compared to partial vial doses in critically ill pediatric patients, including patients receiving extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT).

METHOD

This retrospective review evaluated pediatric patients 0-18 years of age admitted to a 24-bed medical/surgical pediatric intensive care unit between June 1, 2012, and December 31, 2014, who received plasma-derived AT III. Patients received unfractionated heparin, low-molecular-weight heparin, or no anticoagulation. This review included patients who received ECMO and CRRT.

RESULTS

Eighty doses of AT III were administered to 24 patients (38 full vial size doses and 42 partial vial size doses). The AT III level following dose administration was ≥80% for 26 full vial doses (70%) and 16 partial vial doses (41%; p = 0.010). For patients who received multiple doses of AT III, the median time between doses was 45 hours following full vial doses, and 23 hours following partial vial doses (p = 0.011). Seven patients (29%) had documentation of new or increased bleeding. The median waste prevented from rounding doses to full vial sizes was 363 units.

CONCLUSIONS

After receiving AT III doses rounded to full vial sizes, patients were more likely to have a therapeutic AT III level and a longer interval between administrations. Rounding AT III doses to full vial sizes reduces waste and can result in cost savings.

Antithrombin Concentrate Use in Pediatric Extracorporeal Membrane Oxygenation: A Multicenter Cohort Study

OBJECTIVE

To describe antithrombin concentrate use and to compare thrombotic and hemorrhagic outcomes throughout the hospital stay in pediatric subjects who received extracorporeal membrane oxygenation in a Pediatric Health Information System-participating children's hospital.

DESIGN

Retrospective, multi-center, cohort study.

SETTING

Forty-three free-standing children's hospitals participating in Pediatric Health Information System.

SUBJECTS

Children older than or equal to 18 years of age who underwent extracorporeal membrane oxygenation between 2003 and 2012.

INTERVENTIONS

Subjects were classified as receiving antithrombin if they received at least one dose of antithrombin while on extracorporeal membrane oxygenation.

MEASUREMENTS AND MAIN RESULTS

International Classification of Diseases, Ninth Revision, Clinical Modification codes codes were used to identify hemorrhagic and thrombotic complications during their hospitalization. Pediatric Health Information System data were analyzed to determine hospital-length of stay and in-hospital mortality. A total of 1,931 of 8,601 eligible subjects (21.5%) received at least one dose of antithrombin during their extracorporeal membrane oxygenation course. Antithrombin use during extracorporeal membrane oxygenation increased from 2.4% to 51.9% (p < 0.001) over the 10-year study period. Subjects who received antithrombin while on extracorporeal membrane oxygenation were younger (p = 0.02), had more chronic conditions (p < 0.001), and longer hospital stays (p < 0.001). On multivariate analysis, antithrombin use was associated with thrombotic events (odds ratio, 1.55; 95% CI, 1.36-1.77; p < 0.001), hemorrhagic events (odds ratio, 1.27; 95% CI, 1.14-1.42; p < 0.001), and longer hospital length of stays (slope coefficient, 1.05 d; 95% CI, 1.04-1.06; p < 0.001). No difference was observed in mortality (odds ratio, 0.99; 95% CI, 0.89-1.11; p = 0.90).

CONCLUSIONS

In this multicenter retrospective cohort study, subjects who received antithrombin during extracorporeal membrane oxygenation had a higher number of thrombotic and hemorrhagic events throughout the hospitalization and longer length of stays without an associated difference in mortality. While limitations exist with this analysis and results should be interpreted with caution, the fact remains that over half of pediatric patients on extracorporeal membrane oxygenation are currently receiving antithrombin without clear benefit, with extra cost, and potential harms, there needs to be strong consideration for a clinical trial.

Antithrombin Administration During Intravenous Heparin Anticoagulation in the Intensive Care Unit: A Single-Center Matched Retrospective Cohort Study

Unfractionated heparin (UFH) is a frequently utilized indirect anticoagulant that induces therapeutic effect by enhancing antithrombin (AT)-mediated procoagulant enzyme inhibition. In suspected heparin resistance (HR) during cardiopulmonary bypass, AT activity may be decreased and AT supplementation helps restore UFH responsiveness. The benefit of AT supplementation in HR over longer durations of UFH therapy is unclear. The objective of this study was to describe and evaluate the use of AT III concentrate in the intensive care units (ICUs) at our institution for improving UFH therapy response over 72 hours. A total of 44 critically ill patients were included in the analysis-22 patients received at least 1 dose of AT and 22 patients received no AT. Thirty (68.2%) of the 44 patients were receiving mechanical circulatory support. Baseline characteristics were similar between groups. The average AT activity prior to AT supplementation was 57.9% in the treatment group, and the median cumulative dose of AT was 786.5 U (9.26 U/kg) per patient. There were no significant differences observed in proportion of time spent in therapeutic range (31.9% vs 35.2%, P = .65), time to therapeutic goal (16.5 vs 15.5 hours, P = .97), or patients who experienced a bleeding event (5 vs 5, P = .99) between groups. In conclusion, AT supplementation had minimal impact on anticoagulant response in this cohort of ICU patients with mild to moderate HR receiving a prolonged UFH infusion. Additional research is needed to define AT activity targets and to standardize AT supplementation practices in patients receiving prolonged heparin infusion.

Challenges with Navigating the Precarious Hemostatic Balance during Extracorporeal Life Support: Implications for Coagulation and Transfusion Management

For the past four decades, extracorporeal life support (ECLS) has been used to treat critically ill adult and pediatric patients with cardiac and/or respiratory failure, and there are increasingly numbers of centers worldwide performing ECLS for numerous indications. Despite the progress with advancing the technology, hemorrhagic and thrombotic complications are frequently reported and associated with worse outcomes, but the exact cause is often elusive or multifactorial. As a result of the interaction between blood and an artificial circuit, anticoagulation is necessary and there is resultant activation of coagulation, fibrinolysis, as well as, an increased inflammatory response. While unfractionated heparin (UFH) remains the mainstay anticoagulant used during ECLS, there is a paucity of published data to develop a universal anticoagulation guideline and centers are forced to create individualized protocols to guide anticoagulation management while lacking expertise. From an international survey, centers often use a combination of tests, which in turn result in discordant results and confused management. Studies are urgently needed to investigate optimization of current anticoagulation strategies with UFH, as well as, use of alternative anticoagulants and non-thrombogenic biomaterials. Blood transfusion during extracorporeal support typically occurs for several reasons, which includes circuit priming, restoration of oxygen carrying capacity, maintenance of a hemostatic balance, and treatment of hemorrhagic complications. As a result, the majority of patients will have been exposed to at least one blood product during extracorporeal support and transfusion utilization is high. ECLS Centers have adopted transfusion thresholds based upon practice rather than evidence as there have been no prospective studies investigating the efficacy of red cell (RBC) transfusion in patients receiving extracorporeal support. In addition, RBC transfusion has been associated with increased mortality in ECLS in several retrospective studies. Additional studies are needed to establish evidence based thresholds for transfusion support and diagnostics to guide transfusion therapy to assess efficacy of transfusion in this population, as well as, exploration of alternatives to transfusion.

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.

Noncardiac Challenges in the Cardiac ICU: Feeding, Growth and Gastrointestinal Complications, Anticoagulation, and Analgesia

Outcomes following cardiac intensive care unit (CICU) admission are influenced by many factors including initial cardiac diagnosis, surgical complexity, and burden of critical illness. Additionally, the presence of noncardiac issues may have a significant impact on outcomes and the patient experience during and following an intensive care unit stay. This review focuses on three common noncardiac areas which impact outcomes and patient experience in and beyond the CICU: feeding and growth, pain and analgesia, and anticoagulation. Growth failure and feeding dysfunction are commonly encountered in infants requiring cardiac surgery and have been associated with worse surgical and developmental outcomes. Recent studies most notably in the single ventricle population have demonstrated improved weight gain and outcomes when feeding protocols are implemented. Children undergoing cardiac surgery may experience both acute and chronic pain. Emerging research is investigating the impact of sedatives and analgesics on neurodevelopmental outcomes and quality of life. Improved pain scores and standardized management of pain and withdrawal may improve the patient experience and outcomes. Effective anticoagulation is a critical component of perioperative care but may be complicated by inflammation, multiorgan dysfunction, and patient factors. Advances in monitoring of anticoagulation and emerging therapies are reviewed.

The use of an extracorporeal membrane oxygenation anticoagulation laboratory protocol is associated with decreased blood product use, decreased hemorrhagic complications, and increased circuit life

OBJECTIVES

To determine if a comprehensive extracorporeal membrane oxygenation anticoagulation monitoring protocol results in fewer hemorrhagic complications, reduced blood product usage, and increased circuit life.

DESIGN

In September 2011, we augmented our standard extracorporeal membrane oxygenation laboratory protocol to include anti-factor Xa assays, thromboelastography, and antithrombin measurements. We performed a retrospective chart review to determine outcomes for patients placed on extracorporeal membrane oxygenation prior to and after the initiation of our anticoagulation laboratory protocol.

SETTING

Tertiary care, academic children's hospital.

PATIENTS

All patients who were placed on extracorporeal membrane oxygenation at our institution from January 1, 2007, to September 30, 2013.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 261 extracorporeal membrane oxygenation runs before the initiation of the protocol and 105 extracorporeal membrane oxygenation runs after the initiation of the protocol. There were no major changes to our extracorporeal membrane oxygenation circuit or changes to our transfusion threshold during the study period. The indication for extracorporeal membrane oxygenation, age, and severity of illness of the patients were similar before and after protocol initiation. Median blood product usage for packed RBCs, fresh frozen plasma, platelets, and cryoprecipitate decreased significantly after protocol initiation. The occurrence of cannula site bleeding decreased from 22% to 12% (p = 0.04), and surgical site bleeding decreased from 38% to 25% (p = 0.02). Median extracorporeal membrane oxygenation circuit life increased from 3.6 to 4.3 days (p = 0.02). A trend toward increased patient survival was noted, but it did not reach statistical significance.

CONCLUSIONS

We demonstrate an association between an extracorporeal membrane oxygenation anticoagulation laboratory protocol using anti-factor Xa assays, thromboelastography, and antithrombin measurements and a decrease in blood product transfusion, a decrease in hemorrhagic complications, and an increase in circuit life. To our knowledge, this is the first study to demonstrate clinical benefit associated with the use of these laboratory values for patients on extracorporeal membrane oxygenation.