Factors Associated with Bleeding and Thrombosis in Children Receiving Extracorporeal Membrane Oxygenation

Blood transfusion is associated with increased mortality for neonates with congenital diaphragmatic hernia on extracorporeal membrane oxygenation support

BACKGROUND AND OBJECTIVES

Blood transfusion is frequently needed to maintain adequate haemostasis and improve oxygenation for patients treated with extracorporeal membrane oxygenation (ECMO). It is more so for neonates with immature coagulation systems who require surgical intervention such as congenital diaphragmatic hernia (CDH) repair. There is growing evidence suggesting an association between blood transfusions and increased mortality. The aim of this study is to evaluate the association of blood transfusions during the peri-operative period of CDH repair, among other clinical parameters, with mortality in neonates undergoing on-ECMO CDH repair.

MATERIALS AND METHODS

We performed a single centre retrospective chart review of all neonates with CDH undergoing on-ECMO surgical repair from January 2010 to December 2020. Logistic regression was used to investigate associations with survival status.

RESULTS

Sixty-two patients met the inclusion criteria. Platelet transfusions (odds ratio [OR] 1.42, 95% confidence interval [CI]: 1.06-1.90) in the post-operative period and ECMO duration (OR 1.17, 95% CI: 1.05-1.30) were associated with increased mortality. Major bleeding complications had the strongest association with mortality (OR 10.98, 95% CI: 3.27-36.91). Gestational age, birth weight, Apgar scores, sex, blood type, right versus left CDH, venovenous versus venoarterial ECMO and duration of ECMO before CDH repair and circuit change after adjusting for ECMO duration were not significantly associated with survival.

CONCLUSION

Platelet transfusion in the post-operative period and major bleeding are associated with increased mortality in CDH neonates with surgical repair. The data suggest a need to develop robust plans for monitoring and preventing coagulation aberrancies during neonatal ECMO support.

Ultrasound-Guided Dynamic Needle-Tip Positioning Method Is Superior to Conventional Palpation and Ultrasound Method in Arterial Catheterization

Background: Dynamic needle-tip positioning (DNTP) was shown to improve arterial cannulation efficiency with fewer complications than conventional palpation and ultrasound methods by some studies. However, this is still controversial, and we performed this meta-analysis to comprehensively assess its value in arterial cannulation. Methods: A literature search of randomized controlled trials was conducted, and 11 studies were finally included. Efficiency outcomes (first-attempt success, overall success, and total cannulation time) and complications (hematoma, thrombosis, posterior wall puncture, and vasospasm) were separately analyzed. Subgroup analyses in different populations under cannulation were also performed. Results: DNTP was associated with increased first-attempt success (pooled RR = 1.792, p < 0.001), overall success (pooled RR = 1.368, p = 0.001), and decreased cannulation time (pooled SMD = −1.758, p = 0.001) than palpation. DNTP gained even more advantage in small children and infants. No significant difference in these outcomes between DNTP and conventional ultrasound method was detected. Fewer hematoma occurred in DNTP than palpation (pooled RR = 0.265, p < 0.001) or traditional ultrasound (pooled RR = 0.348, p < 0.001). DNPT was also associated with fewer posterior wall punctures (pooled RR = 0.495, p = 0.001) and vasospasm (pooled RR = 0.267, p = 0.007) than traditional ultrasound. Conclusions: DNTP was a better choice in artery cannulation than conventional palpation and ultrasound method, especially in small children and infants.

Novel Coagulation Test Detects Anticoagulation Resistance and Is Associated With Thrombotic Events in Pediatric Patients Requiring Extracorporeal Membrane Oxygenation

Bivalirudin, an IV direct thrombin inhibitor, and unfractionated heparin (UFH) are frequently used anticoagulants in the pediatric critical care setting. An accurate, specific, point-of-care test to quantify and detect anticoagulation resistance is not currently available. This study evaluates the ability of a rapid (< 10 min), micro-volume (< 50 uL) coagulation test to detect and quantify the anticoagulation effect of bivalirudin and UFH using a functional, clot time endpoint in pediatric critical care patients.

DESIGN

Single-site retrospective laboratory sample analysis and chart review.

SETTING

A 105-bed pediatric and cardiac ICUs delivering extracorporeal membrane oxygenation.

SUBJECTS

Forty-one citrated, frozen, biobanked plasma specimens comprising 21 with bivalirudin and 20 with UFH from 15 anticoagulated pediatric patients were analyzed. Thirteen patients were on extracorporeal membrane oxygenation, one had a submassive pulmonary embolism, and one was on a left ventricular assist device.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

A Clotting Time Score (CTS) was derived on each sample. The CTS detected patients that had developed a pathologic clotting event with 100% sensitivity and 82% specificity compared with prothrombin time with 25% sensitivity/76% specificity and activated partial thromboplastin time with 0% sensitivity/0% specificity. Additionally, the CTS detected subtherapeutic anticoagulation in response to UFH in patients that were clinically determined to be UFH resistant requiring alternative anticoagulation with bivalirudin.

CONCLUSIONS

The CTS appears to be a clinically valuable indicator of coagulation status in patients treated with either UFH or bivalirudin. Results outside of the therapeutic range due to inadequate dosing or anticoagulation resistance appeared to be associated with clot formation. CTS testing may reduce the risk of anticoagulation-related complications via the rapid identification of patients at high risk for pathologic thrombotic events.

Association Between Early Change in Arterial Carbon Dioxide Tension and Outcomes in Neonates Treated by Extracorporeal Membrane Oxygenation

The primary objective was to investigate the association between partial pressure of carbon dioxide (PaCO2) change after extracorporeal membrane oxygenation (ECMO) initiation and neurologic outcome in neonates treated for respiratory failure. A retrospective analysis of the Extracorporeal Life Support Organization (ELSO) database including newborns supported by ECMO for respiratory indication during 2015-2020. The closest Pre-ECMO (Pre-ECMO PaCO2) and at 24 hours after ECMO initiation (H24 PaCO2) PaCO2 values allowed to calculate the relative change in PaCO2 (Rel Δ PaCO2 = [H24 PaCO2 - Pre-ECMO PaCO2]/Pre-ECMO PaCO2). The primary outcome was the onset of any acute neurologic event (ANE), defined as cerebral bleeding, ischemic stroke, clinical or electrical seizure, or brain death during ECMO. We included 3,583 newborns (median age 1 day [interquartile range {IQR}, 1-3], median weight 3.2 kg [IQR, 2.8-3.6]) from 198 ELSO centers. The median Rel Δ PaCO2 value was -29.9% [IQR, -46.2 to -8.5]. Six hundred nine (17%) of them had ANE (405 cerebral bleedings, 111 ischemic strokes, 225 seizures, and 6 brain deaths). Patients with a decrease of PaCO2 > 50% were more likely to develop ANE than others (odds ratio [OR] 1.78, 95% confidence interval [CI], 1.31-2.42, p < 0.001). This was still observed after adjustment for all clinically relevant confounding factors (adjusted OR 1.94, 95% CI, 1.29-2.92, p = 0.001). A significant decrease in PaCO2 after ECMO start is associated with ANE among neonates requiring ECMO for respiratory failure. Cautious PaCO2 decrease should be considered after start of ECMO therapy.

Red blood cell volume, but not platelet or plasma volume is associated with mortality in neonatal ECMO

BACKGROUND

Blood product transfusions are necessary for critically ill neonates on extracorporeal membrane oxygenation (ECMO). Transfusions are administered in response to unstudied arbitrary thresholds and may be associated with adverse outcomes. The objective of this study was to identify relationships between blood product components and mortality in neonates receiving ECMO support for respiratory indications.

STUDY DESIGN AND METHODS

A retrospective review of neonates receiving ECMO for respiratory indications from 2002 to 2019 from a single quaternary-referral neonatal intensive care unit (NICU). Demographic and outcome data and transfusion volume (ml/kg/day) were harvested from the medical record, and baseline mortality risk was assessed using NEO-RESCUERS scores. The association between volume of red blood cells (RBC), platelet, plasma transfusion rates (ml/kg/day), and mortality on ECMO were assessed after adjustment for NEO-RESCUERS score. Cox proportional hazards (CPH) competing risk model was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for each variable and mortality outcome.

MEASUREMENTS AND MAIN RESULTS

Among 248 neonates undergoing ECMO for respiratory failure, overall survival was 93%. RBC, platelet, and plasma volume were highly associated with mortality during ECMO in an unadjusted model. After adjusting for NEO-RESCUERS score, RBC volume was associated with increased mortality risk (HR 1.013, 95% CI 1.004-1.022, p = .0043), but platelet and plasma volume were not associated with mortality.

CONCLUSIONS

RBC, but not platelet or plasma volume, is associated with mortality in neonates on ECMO. Our findings refute previous studies demonstrating an association between platelet volume and mortality for neonates on ECMO.

Utility of Routine Head Ultrasounds in Infants on Extracorporeal Life Support: When is it Safe to Stop Scanning?

Intracranial hemorrhage (ICH) can be a devastating complication of extracorporeal life support (ECLS); however, studies on the timing of ICH detection by head ultrasound (HUS) are from 2 decades ago, suggesting ICH is diagnosed by day 5 of ECLS. Given advancements in imaging and critical care, our aim was to evaluate if the timing of ICH diagnosis in infants on ECLS support has changed. Patients <6 months old undergoing ECLS 2011-2020 at a tertiary care children's hospital were included. Primary outcome was timing of ICH diagnosis on HUS. Seventy-four infants underwent ECLS for cardiac (54%) or pulmonary (46%) indications. Venoarterial ECLS was most common (88%). Median ECLS duration was 6 days (range 1-26). Sixteen patients were diagnosed with ICH (21.6%), at a median of 2 days postcannulation (range 1-4). Nearly all were <4 weeks old at cannulation (93.8%). In conclusion, one-fifth of infants developed ICH diagnosed by HUS while on ECLS, all within the first 4 days of ECLS, consistent with previous literature. Despite advances in critical care and imaging technology, the temporality of ICH diagnosis in infants on ECLS is unchanged.

Hemostatic complications and systemic heparinization in pediatric post-cardiotomy veno-arterial extracorporeal membrane oxygenation failed to wean from cardiopulmonary bypass

BACKGROUND

Hemostatic complications and the need for large amounts of blood products are major obstacles during veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Additionally, the occurrence of coagulopathy after cardiopulmonary bypass (CPB) affects systemic heparinization in pediatric post-cardiotomy patients. This study compares hemostatic complications in pediatric post-cardiotomy VA-ECMO patients for failure to wean from CPB with those who received post-cardiotomy VA-ECMO for other indications, while also exploring the relationship between different stages-hemostatic complications and the timing of systemic heparinization.

METHODS

We retrospectively analyzed 146 pediatric patients who received post-cardiotomy VA-ECMO support (CPB-ECMO, n=96 vs. non-CPB-ECMO, n=50) from January 2005 to June 2020. Patients were divided into survivors (n=46) and non-survivors (n=50) according to in-hospital mortality in the CPB-ECMO group. We compared clinical outcomes between the groups, then examined the associations between the timing of systemic heparinization after ECMO implantation and different stages-hemostatic complications, in the CPB-ECMO group.

RESULTS

We found that the risk of early bleeding was significantly increased in patients who failed to wean from CPB. The presence of early bleeding was accompanied by the higher demand for blood products transfusion in the CPB-ECMO group, and for treatment the patients received a longer delayed continuous heparin infusion. As a result of using delayed systemic heparinization to avoid early bleeding, early hemolysis increased in the CPB-ECMO group. A delayed systemic heparinization of 9.5 hours showed the best Youden index results and the overall greatest accuracy in predicting early hemolysis.

CONCLUSIONS

A direct transition from CPB to ECMO in pediatric post-cardiotomy patients significantly increases early bleeding. Delayed systemic heparinization to reduce early bleeding has good discrimination for predicting early hemolysis in the CPB-ECMO group. Coagulopathy is complex in pediatric post-cardiotomy VA-ECMO patients who failed to wean from CPB, and, as such, it is extremely important to monitor coagulation-related indicators in multiple dimensions to determine the timing of systemic heparinization.

Rescue venovenous extracorporeal membrane oxygenation for the deterioration of acute respiratory distress syndrome in pediatric liver transplantation

BACKGROUND

Twenty percent of pediatric patients with BA develop ACLF with increased mortality while awaiting LT. Respiratory complications are common in pediatric ACLF and are associated with increased morbidity and mortality. ARDS is the most severe manifestation of acute respiratory failure with considerable risk of mortality.

METHODS

A 5-month-old girl with post-Kasai BA preoperatively experienced ARDS from RSV infection while awaiting LT. She developed decompensated liver failure with shock, acute kidney injury, coagulopathy, and pulmonary hemorrhage after several episodes of sepsis over the course of 1 month in the PICU. At this stage, RSV was not detected in the patient's tracheal aspirate by real-time polymerase chain reaction. She underwent living donor LT to manage her pre-existing critical state. Following reperfusion during LT, her pre-existing ARDS rapidly deteriorated, which was alleviated by intraoperative VV ECMO.

RESULTS

Severe respiratory acidosis improved rapidly following ECMO, and LT was completed uneventfully. The patient was successfully weaned off ECMO on POD 3.

CONCLUSIONS

This is the first pediatric case rescued by the intraoperative application of ECMO during LT. Our case and cumulative evidence suggest that VV ECMO can serve as rescue therapy for perioperative refractory respiratory failure in pediatric LT.

Mortality prediction in pediatric postcardiotomy veno-arterial extracorporeal membrane oxygenation: A comparison of scoring systems

Background

Pediatric postcardiotomy veno-arterial extracorporeal membrane oxygenation (VA-ECMO) patients have high mortality and morbidity. There are currently three scoring systems available to predict mortality: the Pediatric Extracorporeal Membrane Oxygenation Prediction (PEP) model, Precannulation Pediatric Survival After VA-ECMO (Pedi-SAVE) score, and Postcannulation Pedi-SAVE score. These methods provide risk stratification scores for pediatric patients requiring ECMO for cardiac support. However, comparative validation of these scoring systems remains scarce. We aim to assess the ability of these models to predict outcomes in a cohort of pediatric patients undergoing VA-ECMO after cardiac surgery, and identify predictors of in-hospital mortality.

Methods

A retrospective analysis of 101 children admitted to Fuwai Hospital who received VA-ECMO from January 1, 2010 to December 31, 2020 was performed. Patients were divided into two groups, survivors (n = 49) and non-survivors (n = 52) according to in-hospital mortality. PEP model and Pedi-SAVE scores were calculated. The primary outcomes were the risk factors of in-hospital mortality, and the ability of the PEP model, Precannulation Pedi-SAVE and Postcannulation Pedi-SAVE scores to predict in-hospital mortality.

Results

Postcannulation Pedi-SAVE score accessing the entire ECMO process had the greatest area under receiver operator curve (AUROC), 0.816 [95% confidence interval (CI): 0.733–0.899]. Pre-ECMO PEP model could predict in-hospital mortality [AUROC = 0.691 (95% CI: 0.565–0.817)], and Precannulation Pedi-SAVE score had the poorest prediction [AUROC = 0.582(95% CI: 0.471–0.694)]. Lactate value at ECMO implantation [OR = 1.199 (1.064–1.351), P = 0.003] and infectious complications [OR = 5.169 (1.652–16.172), P = 0.005] were independent risk factors for in-hospital mortality.

Conclusion

Pediatric cardiac ECMO scoring systems, including multiple risk factors before and during ECMO, were found to be useful in this cohort. Both the pre-ECMO PEP model and the Postcannulation Pedi-SAVE score were found to have high predictive value for in-hospital mortality in pediatric postcardiotomy VA-ECMO.

A Comparison of Activated Partial Thromboplastin Time and Activated Coagulation Time for Anticoagulation Monitoring during Extracorporeal Membrane Oxygenation Therapy

BACKGROUND

 Unfractionated heparin is used to prevent coagulation activation in patients undergoing extracorporeal membrane oxygenation (ECMO) support. We designed this study to determine the preferable indicator for anticoagulation monitoring.

METHODS

 We conducted a retrospective study and divided the patients into an activated coagulation time (ACT)-target group and an activated partial thromboplastin time (aPTT)-target group. The correlations between ACT, aPTT, and the heparin dose were explored.

RESULTS

 Thirty-six patients were included (19 aPTT-target and 17 ACT-target patients); a total of 555 matched pairs of ACT/aPTT results were obtained. The correlation between the ACT and aPTT measurements was Spearman's Rank Correlation Coefficient (rs) = 0.518 in all 555 pairs. The Bland-Altman plot showed data points outside the displayed range (51.2-127.7), suggesting that the agreement between ACT and aPTT was poor. The aPTT group had fewer heparin dose changes (2.12 ± 0.68 vs. 2.57 ± 0.64, p = 0.05) and a lower cumulative heparin dose (317.6 ± 108.5 vs. 396.3 ± 144.3, p = 0.00) per day than the ACT group. There was no difference in serious bleeding (9 vs. 5; p = 0.171) or embolism events (3 vs. 3; p = 1.0) or in the red blood cell and fresh frozen plasma transfusion volumes between the ACT- and aPTT-target groups. Similarly, there was no significant difference in the ECMO duration (9 [4-15] days vs. 4 [3-14] days; p = 0.124) or length of ICU hospitalization (17 [5-32] days vs. 13 [4-21] days; p = 0.451) between the groups.

CONCLUSION

 The correlation between ACT and aPTT and the heparin dose was poor. The aPTT group had fewer daily heparin dose changes and a lower cumulative heparin dose per day than the ACT group, with no more bleeding and thrombotic events. Therefore, we recommend aPTT rather than ACT to adjust heparin dose in the absence of better monitoring indicators.

Bleeding and thrombotic events in patients with severe COVID-19 supported with extracorporeal membrane oxygenation: a nationwide cohort study

PURPOSE

To describe bleeding and thrombotic events and their risk factors in patients receiving extracorporeal membrane oxygenation (ECMO) for severe coronavirus disease 2019 (COVID-19) and to evaluate their impact on in-hospital mortality.

METHODS

The ECMOSARS registry included COVID-19 patients supported by ECMO in France. We analyzed all patients included up to March 31, 2022 without missing data regarding bleeding and thrombotic events. The association of bleeding and thrombotic events with in-hospital mortality and pre-ECMO variables was assessed using multivariable logistic regression models.

RESULTS

Among 620 patients supported by ECMO, 29% had only bleeding events, 16% only thrombotic events and 20% both bleeding and thrombosis. Cannulation site (18% of patients), ear nose and throat (12%), pulmonary bleeding (9%) and intracranial hemorrhage (8%) were the most frequent bleeding types. Device-related thrombosis and pulmonary embolism/thrombosis accounted for most of thrombotic events. In-hospital mortality was 55.7%. Bleeding events were associated with in-hospital mortality (adjusted odds ratio (adjOR) = 2.91[1.94-4.4]) but not thrombotic events (adjOR = 1.02[0.68-1.53]). Intracranial hemorrhage was strongly associated with in-hospital mortality (adjOR = 13.5[4.4-41.5]). Ventilation duration before ECMO ≥ 7 days and length of ECMO support were associated with bleeding. Thrombosis-associated factors were fibrinogen ≥ 6 g/L and length of ECMO support.

CONCLUSIONS

In a nationwide cohort of COVID-19 patients supported by ECMO, bleeding incidence was high and associated with mortality. Intracranial hemorrhage incidence was higher than reported for non-COVID patients and carried the highest risk of death. Thrombotic events were less frequent and not associated with mortality. Length of ECMO support was associated with a higher risk of both bleeding and thrombosis, supporting the development of strategies to minimize ECMO duration.

Comparison of the Efficacy of ECMO With or Without IABP in Patients With Cardiogenic Shock: A Meta-Analysis

OBJECTIVE

Studies on extracorporeal membrane oxygenation (ECMO) with and without an intra-aortic balloon pump (IABP) for cardiogenic shock (CS) have been published, but there have been no meta-analyses that compare the efficacy of these two cardiac support methods. This meta-analysis evaluated the outcomes of these two different treatment measures.

METHODS

The PubMed, Embase, Cochrane Library, Web of Science, and Clinical Trials databases were searched until March 2022. Studies that were related to ECMO with or without IABP in patients with CS were screened. Quality assessments were evaluated with the methodological index for nonrandomized studies (MINORS). The primary outcome was in-hospital survival, while the secondary outcomes included duration of ECMO, duration of ICU stay, infection/sepsis, and bleeding. Revman 5.3 and STATA software were used for this meta-analysis.

RESULTS

In total, nine manuscripts with 2,573 patients were included in the systematic review. CS patients who received ECMO in combination with IABP had significantly improved in-hospital survival compared with ECMO alone (OR = 1.58, 95% CI = 1.26-1.98, P < 0.0001). However, there were no significant differences in the duration of ECMO (MD = 0.36, 95% CI = -0.12-0.84, P = 0.14), duration of ICU stay (MD = -1.95, 95% CI = -4.05-0.15, P = 0.07), incidence of infection/sepsis (OR = 1.0, 95% CI = 0.58-1.72, P = 1.0), or bleeding (OR = 1.28, 95% CI = 0.48-3.45, P = 0.62) between the two groups of patients with CS.

CONCLUSION

ECMO combined with IABP can improve in-hospital survival more effectively than ECMO alone in patients with CS.

The Changing Landscape of Anticoagulation in Pediatric Extracorporeal Membrane Oxygenation: Use of the Direct Thrombin Inhibitors

Bleeding and thrombosis frequently occur in pediatric patients with extracorporeal membrane oxygenation (ECMO) therapy. Until now, most patients are anticoagulated with unfractionated heparin (UFH). However, heparin has many disadvantages, such as binding to other plasma proteins and endothelial cells in addition to antithrombin, causing an unpredictable response, challenging monitoring, development of heparin resistance, and risk of heparin-induced thrombocytopenia (HIT). Direct thrombin inhibitors (DTIs), such as bivalirudin and argatroban, might be a good alternative. This review will discuss the use of both UFH and DTIs in pediatric patients with ECMO therapy.

Development and Blood Compatibility of a Stable and Bioactive Metal-Organic Framework Composite Coating for Blood-Circulation Tubing

Medical devices that require substantial contact between blood and a foreign surface would be dramatically safer if constructed from materials that prevent clot formation and coagulation disturbance at the blood-biomaterial interface. Nitric oxide (NO), an endogenous inhibitor of platelet activation in the vascular endothelium, could provide anticoagulation at the blood-surface interface when applied to biomaterials. We investigated an application of a copper-based metal-organic framework, H₃[(Cu₄Cl)₃(BTTri)₈-(H₂O)₁₂]·72H₂O where H₃BTTri = 1,3,5-tris(1H-1,2,3-triazole-5-yl)benzene] (CuBTTri), which has been shown to be an effective catalyst to generate NO from S-nitrosothiols that are endogenously present in blood. A method was developed to apply a CuBTTri composite coating to Tygon medical tubing used for extracorporeal lung support devices. The stability and activity of the coating were evaluated during 72 h dynamic saline flow testing (1.5-2.5 L/min, n = 3) with scanning electron microscopy imaging and inductively coupled mass-spectroscopy analysis. Compatibility of the coating with whole blood was assessed with a panel of hemocompatibility tests during 6 h circulation of swine donor blood in an ex vivo circulation loop constructed with CuBTTri tubing or unmodified Tygon (1.5 L/min blood flow rate, n = 8/group). Thrombus deposition and catalytic activity of the CuBTTri tubing were assessed following blood exposure. The coating remained stable during 72 h saline flow experiments at clinically relevant flow rates. No adverse effects were observed relative to controls during blood compatibility testing, to include no significant changes in platelet count (p = 0.42), platelet activation indicated by P-selectin expression (p = 0.57), coagulation panel values, or methemoglobin fraction (p = 0.18) over the 6 h circulation period. CuBTTri within the coating generated NO following blood exposure in the presence of biologically relevant concentrations of an NO donor. CuBTTri composite coating was stable and blood compatible in this pilot study and requires further investigation of efficacy using in vivo models conducted with clinically relevant blood flow rates and study duration.

Early Levosimendan Administration Improved Weaning Success Rate in Extracorporeal Membrane Oxygenation in Patients With Cardiogenic Shock

Background

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) has been increasingly used in patients with refractory cardiogenic shock (CS) or out-of-hospital cardiac arrest. It is difficult to perform VA-ECMO weaning, which may cause circulatory failure and death. Levosimendan is an effective inotropic agent used to maintain cardiac output, has a long-lasting effect, and may have the potential benefit for VA-ECMO weaning. The study aimed to explore the relationship between the early use of levosimendan and the rate of VA-ECMO weaning failure in patients on VA-ECMO support for circulatory failure.

Methods

All patients who underwent VA-ECMO in our hospital for CS between January 2017 and December 2020 were recruited in this cohort study and divided into two groups: without and with levosimendan use. Levosimendan was used as an add-on to other inotropic agents as early as possible after VA-ECMO setting. The primary endpoint was VA-ECMO weaning success, which was defined as survival without events for 24 h after VA-ECMO withdrawl. The secondary outcomes were cardiovascular and all-cause mortality at the 30-day and 180-day follow-up periods post-VA-ECMO initialization.

Results

A total of 159 patients were recruited for our study; 113 patients were enrolled in the without levosimendan-use group and 46 patients were enrolled in the levosimendan-use group. In levosimendan-use group, the patients received levosimendan infusion within 24 h after VA-ECMO initialization. Similar hemodynamic parameters were noted between the two groups. Poorer left ventricular ejection fraction and a higher prevalence of intra-aortic balloon pumping were observed in the levosimendan group. An improved weaning rate (without vs. with: 48.7 vs. 82.6%; p < 0.001), lower in-hospital mortality rate (without vs. with: 68.1 vs. 43.5%; p = 0.007), and 180-day cardiovascular mortality (without vs. with: 75.3 vs. 43.2%; p < 0.001) were also noted. Patients administered with levosimendan also presented a lower rate of 30-day (without vs. with: 75.3 vs. 41.3%; p = 0.034) and 180-day (without vs. with: 77.0 vs. 43.2%; p < 0.001) all-cause mortality.

Conclusion

Early levosimendan administration may contribute to increasing the success rate of VA-ECMO weaning and may help to decrease CV and all-cause mortality.

Successful use of ECMO in the treatment of acute respiratory distress syndrome associated with SARS-CoV-2 in two pediatric cases

SARS-CoV-2 infection, in the vast majority, affects adult patients. The severity of COVID-19 and mortality are directly correlated with the increasing age of patients and the number of comorbidities. However, with the further development of the COVID-19 pandemic, severe cases of COVID-19 have been reported in children. About 0.8-1% of sick children require hospitalization in an intensive care unit. The main syndromes that cause disease severity and mortality in children are acute respiratory distress syndrome, multisystem inflammation syndrome and multiple organ failure. The rapid development of severe respiratory failure and hypoxemia in respiratory distress syndrome leads to the use of various methods of respiratory therapy, and in case of their ineffectiveness to extracorporeal membrane oxygenation (ECMO). In our report, we present two clinical cases of successful use of ECMO in children with COVID-19, who developed severe ARDS.

Eliminate Unnecessary Laboratory Work to Mitigate Iatrogenic Anemia and Reduce Cost for Patients on Extracorporeal Membrane Oxygenation

Laboratory testing is a helpful tool for clinicians, but can be costly and harmful to patients. A quality improvement project was initiated to reduce laboratory testing for patients receiving extracorporeal membrane oxygenation (ECMO) in a pediatric intensive care unit (PICU) at a tertiary care center. Preliminary data was gathered to demonstrate preimplementation practice, cost, and patient need for packed red blood cell (pRBC) transfusions. A new protocol was created by an interprofessional team based on best practice and benchmarking with high-performing organizations. The project was evaluated using two comparison groups, pre- and postimplementation for anyone receiving ECMO therapy in the PICU. The average laboratory tests per ECMO day decreased by 52% (128.4 vs. 61.1), cost per case decreased by 14.7%, pRBC transfusions decreased from 100% to 85%, length of stay (LOS) decreased by 8 days, and mortality rates decreased by 9.5%. The revised pediatric ECMO laboratory testing guidelines were successfully implemented and reduced laboratory cost without adverse effects on mortality rates or LOS.

Extracorporeal Membrane Oxygenation in Critically Ill Children

Neonatal and pediatric extracorporeal membrane oxygenation (ECMO) has evolved over the past 50 years. Advances in technology, expertise, and application have increased the number of centers providing ECMO with expanded indications for use. However, increasing the use of ECMO in recent years to more medically complex critically ill children has not changed overall survival despite increased experience and improvements in technology. This review focuses on ECMO history, circuits, indications and contraindications, management, complications, and outcome data. The authors highlight important areas of progress, including unintubated and awake patients on ECMO, application during the COVID-19 pandemic, and future directions.

Hemostasis in Pediatric Extracorporeal Life Support: Overview and Challenges

Extracorporeal membrane oxygenation (ECMO) and ventricular assist devices (VADs) are increasingly used in critically ill children. Despite improvements in mechanical design and clinical management, thromboembolic and hemorrhagic events remain significant causes of morbidity and mortality related to the use of both devices. Choice of anticoagulant agents and assays for monitoring continue to present challenges in management. In this review, we describe the incidence and risk factors for thrombosis and hemorrhage, the different types of anticoagulants currently in use, the assays available for monitoring anticoagulation, and management of thromboembolic and bleeding complications in children on mechanical circulatory support (MCS). We conclude by emphasizing the areas that need further study to minimize the risk for thrombosis and hemorrhage in the use of ECMO and VAD in children.

Risk Factors and Outcomes for Patients with Bleeding Complications Receiving Extracorporeal Membrane Oxygenation: An Analysis of the Chinese Extracorporeal Life Support Registry

OBJECTIVE

Bleeding is a severe complication of patients supported with extracorporeal membrane oxygenation (ECMO). This study aimed to analyze the occurrence, risk factors, and clinical outcomes of patients on ECMO with bleeding complications.

METHODS

ECMO cases reported to the multicenter ECMO registry database of the Chinese Society of Extracorporeal Life Support (CSECLS) from January 2017 to December 2020 were enrolled. General information, ECMO indications, application, complications, and patient outcomes were collected and analyzed.

RESULTS

A total of 6541 ECMO patients from 112 centers were enrolled. Overall, 1185 patients (18.1%) presented with one of the following bleeding complications, including 82 cases (1.3%) with severe bleeding during ECMO catheterization, 462 cases (7.1%) with bleeding at the ECMO cannulation site, 200 cases (3.5%) with bleeding at the surgical site, 180 cases (2.8%) with cerebral hemorrhage, 99 cases (1.5%) with pulmonary hemorrhage, 200 cases (3.5%) with gastrointestinal hemorrhage, 82 cases (1.3%) with ECMO withdrawal, and 118 (1.8%) deaths due to severe bleeding. Extracorporeal cardiopulmonary resuscitation (ECPR) patients had the highest incidence of bleeding complications (22.4%), followed by those on circulatory support (18.7%) and respiratory support (15.4%) (p<0.001). Multivariate analysis showed that pediatric patients (odds ratio [OR] 1.509, p<0.001), patients receiving renal replacement therapy (OR 1.932, p<0.001), and patients receiving central ECMO cannulation (OR 3.023, p<0.001) were independent risk factors for all bleeding complications, while peripheral cannulation (OR 0.712, p<0.001) was an independent protective factor. Patients with any bleeding complication had significantly higher in-hospital mortality than patients without (61.9% vs. 46.3%, p<0.001).

CONCLUSION

Up to 18.1% of ECMO patients in the CSECLS registry experienced bleeding complications, which was associated with higher in-hospital mortality, especially in patients who received ECPR, patients on circulatory support, and pediatric patients, which should arouse the attention of clinicians.

Viscoelastic Testing in Pediatric Mechanical Circulatory Support

Pediatric mechanical circulatory support can be lifesaving. However, managing anticoagulation is one of the most challenging aspects of care in patients requiring mechanical circulatory support. Effective anticoagulation is even more difficult in pediatric patients due to the smaller size of their blood vessels, increased turbulent flow, and developmental hemostasis. Recently, viscoelastic testing (VET) has been used as a qualitative measure of anticoagulation efficacy in patients receiving extracorporeal membrane oxygenation (ECMO) and ventricular assist devices (VAD). Thromboelastography (TEG®) and thromboelastometry (ROTEM®) provide a global qualitative assessment of hemostatic function from initiation of clot formation with the platelet-fibrin interaction, platelet aggregation, clot strength, and clot lysis. This review focuses on the TEG®/ROTEM® and important laboratory and patient considerations for interpretation in the ECMO and VAD population. We summarize the adult and pediatric ECMO/VAD literature regarding VET values, VET-platelet mapping, utility over standard laboratory monitoring, and association with outcome measures such as blood product utilization, bleeding, and thrombosis.

Risk factors for hemolysis with centrifugal pumps in pediatric extracorporeal membrane oxygenation: Is pump replacement an answer?

INTRODUCTION

Hemolysis during pediatric extracorporeal membrane oxygenation (ECMO) is associated with increased risk for renal failure and mortality.

OBJECTIVES

We aim to describe risk factors for hemolysis in pediatric ECMO supported by centrifugal pumps.

METHODS

We conducted an analysis of retrospective data collected at an academic children's hospital from January 2017 to December 2019.

MEASUREMENTS AND RESULTS

Plasma-free hemoglobin (PFH) levels were measured daily, and hemolysis was defined as PFH>50 mg/dL. Of 46 ECMO runs over 528 ECMO days, hemolysis occurred in 23 (58%) patients over a total of 40 (8%) ECMO days. In multivariable logistic regression models, VA-ECMO (aOR=4.69, 95% CI: 1.01-21.83) and higher hemoglobin (aOR = 1.38, 95% CI: 1.06-1.81) were independently associated with hemolysis. There were also non-significant trends toward increased risk for hemolysis with higher rotational pump speed (aOR=2.39, 95% CI: 0.75-7.65), higher packed red blood cell transfusions (aOR=1.15, 95% CI: 0.99-1.34), and higher cryoprecipitate transfusions (aOR=2.01, 95% CI: 0.83-4.86). Isolated pump exchanges that were performed in 12 patients with hemolysis led to significant decreases in PFH levels within 24 h (89 vs 11 mg/dL, p<0.01).

CONCLUSIONS

Hemolysis is common in pediatric ECMO using centrifugal pumps. Avoidance of high pump speeds and conservative administration of blood products may help to mitigate the risk for hemolysis. Furthermore, pump exchange may be an effective first-line treatment for hemolysis.

Passive high-frequency microrheology of blood

Indicative of various pathologies, blood properties are under intense scrutiny. The hemorheological characteristics are traditionally gauged by bulk, low-frequency indicators that average out critical information about the complex, multi-scale, and multi-component structure. In particular, one cannot discriminate between the erythrocytes contribution to global rheology and the impact of plasma. Nevertheless, in their fast stochastic movement, before they encounter each other, the erythrocytes probe the subtle viscoelasticity of their protein-rich environment. Thus, if these short time scales can be resolved experimentally, the plasma properties could be determined without having to separate the blood components; the blood is practically testing itself. This microrheological description of blood plasma provides a direct link between the composition of whole blood and its coagulability status. We present a parametric model for the viscoelasticity of plasma, which is probed by the erythrocytes over frequency ranges of kilohertz in a picoliter-sized volume. The model is validated both in vitro, using artificial hemo-systems where the composition is controlled, as well as on whole blood where continuous measurements provide real-time information. We also discuss the possibility of using this passive microrheology as an in vivo assay for clinically relevant situations where the blood clotting condition must be observed and managed continuously for diagnosis or during therapeutic procedures at different stages of hemostatic and thrombotic processes.

Consensus Statement: Hemostasis Trial Outcomes in Cardiac Surgery and Mechanical Support

BACKGROUND

Research evaluating hemostatic agents for the treatment of clinically significant bleeding has been hampered by inconsistency and lack of standardized primary clinical trial outcomes. Clinical trials of hemostatic agents in both cardiac surgery and mechanical circulatory support, such as extracorporeal membrane oxygenation and ventricular assist devices, are examples of studies that lack implementation of universally accepted outcomes.

METHODS

A subgroup of experts convened by the National Heart, Lung, and Blood Institute and the US Department of Defense developed consensus recommendations for primary outcomes in cardiac surgery and mechanical circulatory support.

RESULTS

For cardiac surgery the primary efficacy endpoint of total allogeneic blood products (units vs mL/kg for pediatric patients) administered intraoperatively and postoperatively through day 5 or hospital discharge is recommended. For mechanical circulatory support outside the perioperative period the recommended primary outcome for extracorporeal membrane oxygenation is a 5-point ordinal score of thrombosis and bleeding severity adapted from the Common Terminology Criteria for Adverse Events version 5.0. The recommended primary endpoint for ventricular assist device is freedom from disabling stroke (Common Terminology Criteria for Adverse Events AE ≥ grade 3) through day 180.

CONCLUSIONS

The proposed composite risk scores could impact the design of upcoming clinical trials and enable comparability of future investigations. Harmonizing and disseminating global consensus definitions and management guidelines can also reduce patient heterogeneity that would confound standardized primary outcomes in future research.

Extracorporeal membrane oxygenation in children receiving haematopoietic cell transplantation and immune effector cell therapy: an international and multidisciplinary consensus statement

Use of extracorporeal membrane oxygenation (ECMO) in children receiving haematopoietic cell transplantation (HCT) and immune effector cell therapy is controversial and evidence-based guidelines have not been established. Remarkable advancements in HCT and immune effector cell therapies have changed expectations around reversibility of organ dysfunction and survival for affected patients. Herein, members of the Extracorporeal Life Support Organization (ELSO), Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) Network (HCT and cancer immunotherapy subgroup), the Pediatric Diseases Working Party of the European Society for Blood and Marrow Transplantation (EBMT), the supportive care committee of the Pediatric Transplantation and Cellular Therapy Consortium (PTCTC), and the Pediatric Intensive Care Oncology Kids in Europe Research (POKER) group of the European Society of Pediatric and Neonatal Intensive Care (ESPNIC) provide consensus recommendations on the use of ECMO in children receiving HCT and immune effector cell therapy. These are the first international, multidisciplinary consensus-based recommendations on the use of ECMO in this patient population. This Review provides a clinical decision support tool for paediatric haematologists, oncologists, and critical care physicians during the difficult decision-making process of ECMO candidacy and management. These recommendations can represent a base for future research studies focused on ECMO selection criteria and bedside management.

Airway Emergencies Due to Anterior Mediastinal T-Lymphoblastic Lymphoma Managed With Planned Extracorporeal Membrane Oxygenation and Endotracheal Stent: A Case Report and Literature Review

Anterior mediastinal tumors can occasionally cause acute respiratory failure by compressing the trachea and bronchi. In such cases, sedative muscle relaxants during tracheal intubation can cause fatal complete tracheal obstruction. We encountered a 15-year-old male patient with T-lymphoblastic lymphoma (T-LBL) of the anterior mediastinum. For his airway emergency due to the stenosis extended from the lower part of the trachea to the tracheal bifurcation, venovenous (VV) extracorporeal membrane oxygenation (ECMO) was introduced from the femoral vein under local anesthesia. After a short period of tracheal intubation management, an endotracheal stent (ES) was immediately placed in the lower trachea. We performed a needle biopsy, and he was diagnosed with T-LBL. Following the diagnosis, chemotherapy was introduced. The ES was able to secure sufficient tracheal diameter, and ECMO and ventilation were promptly discontinued. In the case of tracheal stenosis from the lower part of the trachea due to anterior mediastinal tumor, depending on the degree of stenosis, VV ECMO can be considered. Moreover, ES can lead to early weaning from VV ECMO and a ventilator.

Coagulation in pediatric extracorporeal membrane oxygenation: A systematic review of studies shows lack of standardized reporting

Objectives

Extracorporeal membrane oxygenation (ECMO) involves complex coagulation management and frequent hemostatic complications. ECMO practice between centers is variable. To compare results between coagulation studies, standardized definitions and clear documentation of ECMO practice is essential. We assessed how study population, outcome definitions, and ECMO-, coagulation-, and transfusion-related parameters were described in pediatric ECMO studies.

Data sources

Embase, Medline, Web of Science, Cochrane Library and Google Scholar.

Study selection

English original studies of pediatric ECMO patients describing hemostatic tests or outcome.

Data extraction

Eligibility was assessed following PRISMA guidelines. Study population, outcome and ECMO-, coagulation, and transfusion parameters were summarized.

Data synthesis

A total of 107 of 1312 records were included. Study population parameters most frequently included (gestational) age (79%), gender (60%), and (birth) weight (59%). Outcomes, including definitions of bleeding (29%), thrombosis (15%), and survival (43%), were described using various definitions. Description of pump type, oxygenator and cannulation mode occurred in 49%, 45%, and 36% of studies, respectively. The main coagulation test (53%), its reference ranges (49%), and frequency of testing (24%) were the most prevalent reported coagulation parameters. The transfusion thresholds for platelets, red blood cells, and fibrinogen were described in 27%, 18%, and 18% of studies, respectively.

Conclusions

This systematic review demonstrates a widespread lack of detail or standardization of several parameters in coagulation research of pediatric ECMO patients. We suggest several parameters that might be included in future coagulation studies. We encourage the ECMO community to adopt and refine this list of parameters and to use standardized definitions in future research.

Bivalirudin versus heparin in adult and pediatric patients with extracorporeal membrane oxygenation therapy: a systematic review and meta-analysis

BACKGROUND

Our study sought to investigate the efficacy and safety of bivalirudin versus those of unfractionated heparin (UFH) in patients undergoing extracorporeal membrane oxygenation (ECMO).

METHODS

PubMed, EMBASE and Cochrane Library were searched for studies enrolling ECMO patients on bivalirudin and UFH (from inception till July 2021). Meta-analysis was conducted. The I² statistic and p value were used in measuring heterogeneity, and random effects or fixed-effect model was adopted. The Newcastle-Ottawa Scale was used for the risk of bias assessment. Sensitivity and subgroup analyses were undertaken. We performed Egger's test to evaluate publication bias.

RESULTS

Fourteen eligible retrospective observational studies with 1501 subjects were identified. Compared with UFH, bivalirudin significantly reduced the risk of in-circuit thrombosis (OR = 0.44, 95% CI [0.31-0.61], p = 0.000), thrombosis (OR = 0.61, 95% CI [0.45-0.83], p = 0.002) and hospital mortality (OR = 0.78, 95% CI [0.61-0.99], p = 0.04) and had a positive impact on survival ECMO (OR = 1.50, 95% CI [1.04-2.16], p = 0.032). Decrease in risk of bleeding (OR = 0.36, 95% CI [0.14-0.91], p = 0.031) associated with bivalirudin was observed. Sources of heterogeneity were identified, and sensitivity analysis revealed similar results.

CONCLUSION

Our meta-analysis suggested that bivalirudin was associated with the decreased risk of in-circuit thrombosis, thrombosis, hospital mortality and bleeding in patients on ECMO and improved survival ECMO, indicating the superiority of bivalirudin to UFH in terms of efficacy and safety.

Risk Factors Associated With Bleeding in Children With Cardiac Disease Receiving Extracorporeal Membrane Oxygenation: A Multi-Center Data Linkage Analysis

Background: Bleeding is a common complication of extracorporeal membrane oxygenation (ECMO) for pediatric cardiac patients. We aimed to identify anticoagulation practices, cardiac diagnoses, and surgical variables associated with bleeding during pediatric cardiac ECMO by combining two established databases, the Collaborative Pediatric Critical Care Research Network (CPCCRN) Bleeding and Thrombosis in ECMO (BATE) and the Extracorporeal Life Support Organization (ELSO) Registry.

Methods: All children (<19 years) with a primary cardiac diagnosis managed on ECMO included in BATE from six centers were analyzed. ELSO Registry criteria for bleeding events included pulmonary or intracranial bleeding, or red blood cell transfusion >80 ml/kg on any ECMO day. Bleeding odds were assessed on ECMO Day 1 and from ECMO Day 2 onwards with multivariable logistic regression.

Results: There were 187 children with 114 (61%) bleeding events in the study cohort. Biventricular congenital heart disease (94/187, 50%) and cardiac medical diagnoses (75/187, 40%) were most common, and 48 (26%) patients were cannulated directly from cardiopulmonary bypass (CPB). Bleeding events were not associated with achieving pre-specified therapeutic ranges of activated clotting time (ACT) or platelet levels. In multivariable analysis, elevated INR and fibrinogen were associated with bleeding events (OR 1.1, CI 1.0–1.3, p = 0.02; OR 0.77, CI 0.6–0.9, p = 0.004). Bleeding events were also associated with clinical site (OR 4.8, CI 2.0–11.1, p < 0.001) and central cannulation (OR 1.75, CI 1.0–3.1, p = 0.05) but not with cardiac diagnosis, surgical complexity, or cannulation from CPB. Bleeding odds on ECMO day 1 were increased in patients with central cannulation (OR 2.82, 95% CI 1.15–7.08, p = 0.023) and those cannulated directly from CPB (OR 3.32, 95% CI 1.02–11.61, p = 0.047).

Conclusions: Bleeding events in children with cardiac diagnoses supported on ECMO were associated with central cannulation strategy and coagulopathy, but were not modulated by achieving pre-specified therapeutic ranges of monitoring assays.

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.

Antimicrobial Prophylaxis and Anticoagulation Therapy in Pediatric ECMO: A Survey Study

OBJECTIVE

The purpose was to characterize antimicrobial and anticoagulation therapies used in health systems with children receiving extracorporeal membrane oxygenation (ECMO).

METHODS

An anonymous electronic survey assessing health system demographics and antimicrobial and anticoagulation therapies during ECMO was distributed to the American College of Clinical Pharmacy Pediatric Practice and Research Network and the Pediatric Pharmacy Association Critical Care Special Interest Group. The primary objective was to identify the number of respondents using antimicrobial prophylaxis for ECMO cannulation and ECMO runs. Secondary objectives included the first- and second-line anticoagulants and anticoagulation laboratory parameters. Additionally, the antimicrobial regimens and the dosing and administration of antithrombin III (AT III) with systemic anticoagulation were collected. Descriptive statistics were employed.

RESULTS

The questionnaire was completed by 38 respondents from 33 health systems; respondents practiced in the pediatric ICU (n = 20; 52.6%), cardiovascular ICU (n = 14; 36.8%), and neonatal ICU (n = 4; 10.5%). Twenty-eight (73.6%) respondents use antimicrobial prophylaxis during ECMO cannulation or ECMO runs, with most units using cefazolin monotherapy. Thirty-five (92.1%) respondents use heparin as the first-line anticoagulant and used a variety of laboratory tests including anti-factor Xa, activated clotting time, and activated partial thromboplastin time. The most common second-line anticoagulant was bivalirudin (n = 24; 63.2%). Thirty-six (94.7%) respondents use AT III with heparin, with most patients receiving AT III dosing calculated based on a formula for the desired AT III concentration.

CONCLUSIONS

The majority of respondents use antimicrobial prophylaxis, but variations in the regimens were noted. Heparin was the most common anticoagulant, but variations in laboratory monitoring and concomitant use of AT III were found.

Hirudotherapy for limb ischemia in the pediatric intensive care unit: A retrospective observational cohort

BACKGROUND

Acute limb ischemia due to microvascular malperfusion may be refractory to initial therapies. Medicinal leech therapy (hirudotherapy) has been attempted in plastic and reconstructive surgery to improve venous congestion in ischemic flaps; however, there are minimal reports related to ischemia secondary to arterial malperfusion. We evaluated a pediatric cohort from an academic intensive care unit with refractory limb ischemia in whom hirudotherapy was attempted to elucidate its use and outcomes.

METHOD

Institutional patient database was queried to identify pediatric patients (<18 years) who received hirudotherapy in the pediatric critical care unit and met inclusion/exclusion criteria. Patient charts were evaluated for indices including demographics, primary disease, coagulative status, vascular access, vasoactive medication dosing, bleeding, leech use, limb and mortality outcomes. Data was evaluated to identify trends or suspected impact on outcomes.

RESULTS

Hirudotherapy was used in 7 patients for limb ischemia, 5 with congenital heart disease, and 2 others with viremic shock. Time to leech application following recognition of ischemia averaged 3 days, with duration of use averaging 3.9 days. Five patients discontinued therapy due to bleeding. Mortality rate was 57%, all secondary to multiorgan failure. In 3 surviving patients, 4 of 5 treated limbs resulted in at minimum partial amputation. Vasoactive-inotropic score tended higher prior to leech application, suggesting a vasoconstrictive pathway for arterial malperfusion. No identifiable trends appeared associated with salvaged limb or adverse effects. Blood loss predictably increased with leech application, as did total transfusion requirement.

CONCLUSION

This case series establishes baseline data for use of hirudotherapy in critically ill children with acute limb ischemia caused by arterial malperfusion. Based on this retrospective cohort, we cannot recommend routine use of hirudotherapy for acute limb ischemia from arterial malperfusion in the pediatric intensive care unit. Application of leeches should be aligned with a protocol defining start and stop parameters, standardized leech utilization, and monitoring for adverse outcomes. Future study would benefit from consensus definitions of study outcomes, including perfusion recovery, tissue/limb salvage and bleeding manifestations. Additional prospective studies are needed prior to any standard or systematic recommendations for use.

Effect of Platelet Transfusions on Extracorporeal Life Support Oxygenator's Function

OBJECTIVE

Bleeding is a common complication of extracorporeal membrane oxygenation (ECMO), leading to increased mortality. Since one of its main complications is bleeding, platelet transfusions are frequently prescribed for children on ECMO. However, there is currently very little information on the effect of platelet transfusions on the function of the ECMO oxygenator. Our objective was to describe the effect of platelet transfusions on oxygenator function.

METHODS

In this retrospective study, we included all children (<18 years) who received ECMO support in our pediatric intensive care unit (PICU) between January 2017 and December 2019. Oxygenator function, measured before and after platelet transfusion, was assessed by post-oxygenator P _ECMO O₂ and the gradient in pre- post-oxygenator pressures (Delta Pressure).

RESULTS

Over 3 years, we analyzed 235 platelet transfusions from 55 children who received ECMO support. Thirty-two (80%) of children were on veno-arterial ECMO and majority of them were peripherally cannulated. When looking at all transfusions, the post-transfusion change in delta-pressure was 0.1 mmHg (p = 0.69) and post-membrane P _ECMO O₂ was 6 mmHg (p = 0.49). However, in the subgroup with the lowest quartile of pre-transfusion oxygenator function, the post-transfusion change in delta-pressure was -5.2 ± 2.7 mmHg (p < 0.001) and the post-transfusion change in P _ECMO O₂ was -118 ± 49 (p < 0.001). The area under the ROC curve for the pre-transfusion delta-pressure and P _ECMO O₂ to predict a worsening of the oxygenator function were 0.72 (95%CI 0.63-0.81) and 0.71 (95%CI 0.64-0.78), respectively. Using regression models, pre-transfusion delta-pressure and P _ECMO O₂ were the only independent factors associated with oxygenator function worsening (p < 0.001).

CONCLUSION

Our study suggests that overall, platelet transfusions do not seem to impact the ECMO oxygenator's function. However, in the subgroup of patients with the lowest pre-transfusion oxygenator function, platelet transfusions were independently associated with a worsening function. Future studies should investigate if this warrants adjustments of the anticoagulation strategy around the platelet transfusion, especially among patients with lower oxygenator function.

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.

Clinical Features and Risk Factors Analysis for Hemorrhage in Adults on ECMO

Background: The use of extracorporeal membrane oxygenation (ECMO) to support critically ill patients with cardiorespiratory dysfunction has increased over the last decades. However, hemorrhagic complications occur frequently during ECMO support, and this has a significant impact on morbidity and mortality. Thus, this study aimed to identify the risk factors for hemorrhage in patients receiving ECMO.

Methods: Our retrospective study included 60 patients, who were admitted to the Taihe Hospital in Shiyan City, Hubei Province, China from February 2017 to October 2020. About 18 patients developed hemorrhagic complications, and 42 patients did not demonstrate such complications. Data regarding patient demography, laboratory tests, and clinical manifestations prior to ECMO were collected to analyze their clinical features. Univariable and multivariable logistic analyses were used to explore the risk factors for hemorrhage in adults on ECMO. The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of the binary logistic model. The amount of blood transfusions was compared between the two groups, and the activated partial thromboplastin time (APTT), platelet count, and hemoglobin level before the initiation of ECMO.

Results: Logistic analysis showed that a longer duration of ECMO support, higher APTT, and lower platelet count prior to ECMO were independent risk factors for hemorrhage in adults on ECMO. In addition, we found that the cannula site was the most common bleeding site. Most bleeding events occurred within the first 3 days of ECMO therapy. After the ECMO initiation, APTT was prolonged while the platelet count and hemoglobin levels were decreased. The amount of blood transfusion was significantly higher in the hemorrhage group than in the non-hemorrhage group.

Conclusions: Clinicians should evaluate the risk of hemorrhage based on the coagulation function of patients, underlying disease, and the duration of ECMO support. In the first 3 days during ECMO support, special attention should be given to the cannula site, mucosal, and dermal regions, and digestive tract to detect any signs of hemorrhage. Moreover, increasing the platelet count transfusion threshold and accurately determining the amount of blood transfusion required may prevent bleeding events.

Thrombosis in Extracorporeal Membrane Oxygenation (ECMO) Circuits

Thrombosis in extracorporeal membrane oxygenation (ECMO) circuits remains a frequent complication. We characterize the location, extent, structure, and clinical implications of thrombi in 53 ECMO circuits from 46 pediatric patients. The tubing, pump, and oxygenator were examined for visible thrombi. Representative samples of thrombi were collected for histologic, immunofluorescence, and immunohistochemical analysis. Thrombi were found in 81% of ECMO circuits. The most clinically significant were inflow oxygenator membrane surface thrombi (11% of circuits), arterial tubing thrombi (30%), and venous tubing (26%) or connector thrombi (26%). Oxygenator membrane surface thrombi resulted in rapidly increasing delta pressure across the oxygenator over 1-2 days, oxygenator failure, and circuit replacement. Oxygenator membrane surface thrombi were associated with intravascular venous thrombosis and bacterial infection before starting ECMO. Arterial cannula/tubing thrombi led in one case to aortic and mesenteric artery thrombosis followed by bowel infarction. In 11% of cases, venous tubing thrombi grew large enough to break off and embolize to the pump, resulting in increased hemolysis. Antifibrinolytic therapy during ECMO was associated with an increased risk of pump thromboembolism. Other less clinically significant thrombi included pump axle thrombi with thrombus fragments trapped in the oxygenator (45%), and deep oxygenator membrane thrombi (15%). Examination of ECMO circuits after removal is a useful quality improvement tool that can elucidate the cause of circuit problems, indicate patients at increased risk of thrombosis, and suggest areas for possible improvements.

Neurological Outcome According to the Site of Cannulation in Septic Children Supported by Venoarterial Extracorporeal Membrane Oxygenation

The impact of cervical cannulation on neurologic outcome has not been yet studied among children receiving venoarterial extracorporeal membrane oxygenation (VA-ECMO) in the context of severe sepsis or septic shock. A retrospective cohort study was performed using the extracorporeal life support organization (ELSO) registry. A total of 559 children weighing less than 20 kg with a primary or secondary diagnosis of severe sepsis, septic shock or toxic shock syndrome were included between January 1, 2010, and December 31, 2019. Cervical cannulation was performed in 485 children (87%) and central cannulation in 74 children (13%). The prevalence of acute neurologic event (ANE) was 32%, including clinical and/or electroencephalographic seizures, cerebral infarction, cerebral hemorrhage, and/or brain death. In multivariable analysis, we did not find an association between cervical cannulation and greater/lesser odds of ANE during ECMO (adjusted odds ratio [aOR] = 1.39, 95% confidence interval [CI] 0.72-2.65; P = 0.326). Only pre-ECMO acidosis was independently associated with the development of ANE (pH < 6.99; aOR = 2.71, 95% CI 1.34-5.49; P = 0.006; pH 6.99 to <7.12; aOR = 2.57, 95% CI 1.37-4.82; P = 0.003). Thus, the site of cannulation appears not as a modifiable neurologic risk factor in this young septic population.

Analysis of Viscoelastic Testing in Pediatric Patients Using the Pediatric Extracorporeal Membrane Oxygenation Outcomes Registry

Use of viscoelastic tests (VETs), including thromboelastography (TEG) and rotational thromboelastometry (ROTEM), is increasing in the management of anticoagulation in extracorporeal membrane oxygenation (ECMO) patients. A retrospective review of data on 265 pediatric (<20 years old) ECMO patients who underwent VET and were submitted to the Pediatric ECMO Outcomes Registry (PEDECOR) was conducted to describe common coagulopathies in patients who underwent VET; associations between the VET parameters and traditional tests of coagulation; and comparisons in blood product usage in patients who underwent VET with those who did not. We calculated patient-level summary statistics and assessed differences between the groups using χ2 tests (categorical variables) and Kruskal-Wallis and Wilcoxon rank-sum tests (continuous variables). Viscoelastic test was utilized in 77% of patients in the analysis. Platelet dysfunction was the most common abnormality identified by TEG (30.8%) and ROTEM (9.7%). Bleeding patients who had VET performed received more cryoprecipitate transfusions than those who did not have VET (VET median = 9.7 ml/kg; interquartile range (IQR) = 4.3-22.0 ml/kg vs. no VET median = 5.1 ml/kg; IQR = 0-10.4 ml/kg; p = 0.0013). Given the growing use of VET in pediatric ECMO patients, further studies evaluating VET in managing complications as well as aiding in titration of anticoagulation therapy are needed.

A nationwide database analysis of demographics and outcomes related to Extracorporeal Membrane Oxygenation (ECMO) in congenital diaphragmatic hernia

PURPOSE

The aim of the study was to understand the use of Extracorporeal Membrane Oxygenation (ECMO) in congenital diaphragmatic hernia (CDH) and its outcomes.

METHODS

The 2016 Kid's Inpatient Database (KID) obtained from the national Healthcare Cost and Utilization Project (HCUP) was used to obtain CDH birth, demographic, and outcome data associated with ECMO use. Categorical variables were analyzed and odds ratios (OR) with 95% confidence intervals (CI) are reported for variables found to have significance (p < 0.05). Appropriate regressions were used for comparing categorical and continuous data using SPSS 25 for Macintosh.

RESULTS

The database contained 1189 cases of CDH, of which 133 (11.2%) received ECMO. The overall mortality of neonates with CDH was 18.9% (225/1189). Newborns with CDH on ECMO had a survival of 46% (61/133) compared to 85.5% without ECMO (903/1056) (OR 6.966, p < 0.001, 95% CI 4.756-10.204). ECMO increased length of stay from 24.6 to 69.8 days (OR 2.834, p < 0.001, 95% CI 2.768-2.903) and average cost from $375,002.20 to $1641,586.83 (OR 4.378, p < 0.001, 95% CI 3.341-5.735).

CONCLUSIONS

Increased length of stay, costs, and outcomes with ECMO use in CDH should prompt an examination of criteria necessitating ECMO.

Impact of Arterial Carbon Dioxide and Oxygen Content on Cerebral Autoregulation Monitoring Among Children Supported by ECMO

BACKGROUND

Cerebral autoregulation (CA) impairment is associated with neurological complications among children supported by extracorporeal membrane oxygenation (ECMO). Severe variations of arterial CO₂ (PaCO₂) and O₂ (PaO₂) tension after ECMO onset are common and associate with mortality and poor neurological outcome. The impact of gas exchange on CA among critically ill patients is poorly studied.

METHODS

Retrospective analysis of data collected prospectively from 30 children treated with veno-arterial or veno-venous ECMO in the PICU of Nantes University Hospital, France. A correlation coefficient between the variations of regional cerebral oxygen saturation (rSO₂) and the variations of mean arterial blood pressure (MAP) was calculated as an index of CA (cerebral oxygenation reactivity index, COx). Cox-MAP plots were investigated allowing determining lower limit of autoregulation (LLA) and upper limit of autoregulation (ULA) limits of autoregulation. Age-based normal blood pressure was used to adjust the MAP, LLA, and ULA data from each patient and then reported as percentage (nMAP, nLLA, and nULA, respectively). RSO₂, COx, nMAP, nLLA, and nULA values were averaged over one hour before each arterial blood gas (ABG) sample during ECMO run.

RESULTS

Thirty children (median age 4.8 months [Interquartile range (IQR) 0.7-39.1], median weight 5 kg [IQR 4-15]) experiencing 31 ECMO runs were included in the study. Three hundred and ninety ABGs were analyzed. The highest values of COx were observed on day 1 (D1) of ECMO. The relationship between COx and PaCO₂ was nonlinear, but COx values tended to be lower in case of hypercapnia compared to normocapnia. During the whole ECMO run, a weak but significant correlation between PaCO₂ and nULA was observed (R = 0.432, p = 0.02). On D1 of ECMO, this correlation was stronger (R = 0.85, p = 0.03) and a positive correlation between nLLA and PaCO₂ was also found (R = 0.726, p < 0.001). A very weak negative correlation between PaO₂ and nULA was observed within the whole ECMO run and on D1 of ECMO (R =  -0.07 p = 0.04 and R =  -0.135 p =  <0.001, respectively). The difference between nULA and nLLA representing the span of the autoregulation plateau was positively correlated with PaCO₂ and negatively correlated with PaO₂ (R = 0.224, p = 0.01 and R =  -0.051, p = 0.004, respectively).

CONCLUSIONS

We observed a complex relationship between PaCO₂ and CA, influenced by the level of blood pressure. Hypercapnia seems to be globally protective in normotensive or hypertensive condition, while, in case of very low MAP, hypercapnia may disturb CA as it increases LLA. These data add additional arguments for very cautiously lower PaCO₂, especially after ECMO start.

Coagulation complications after conversion from roller to centrifugal pump in neonatal and pediatric extracorporeal membrane oxygenation

BACKGROUND/PURPOSE

Coagulation complications are frequent, unwanted occurrences in extracorporeal membrane oxygenation (ECMO) treatment, possibly influenced by the pump in the ECMO-circuit. We hypothesized that fewer complications would occur with a smaller, heparin-coated ECMO system with a centrifugal pump (CP) than with one with a roller pump (RP) and that after conversion, complication rates would decrease over time.

METHODS

This single-center, retrospective chart study included all first neonatal and pediatric ECMO runs between 2009 and 2015. Differences between groups were assessed with Mann-Whitney U tests and Kruskal-Wallis tests. Determinants of complication rates were evaluated through Poisson regression models. The CP group was divided into three consecutive groups to assess whether complication rates decreased over time.

RESULTS

The RP group comprised 90 ECMO runs and the CP group 82. Hemorrhagic complication rates were significantly higher with the CP than with the RP, without serious therapeutic consequences, while thrombotic complications rates were unaffected. Intracranial hemorrhage rates and coagulation-related mortality rates were similar. Gained experience with the CP did not improve complication rates or survival over time.

CONCLUSIONS

Although the CP seems safe, it does not seem beneficial over the RP. Further research is warranted on how pump type affects coagulation, taking into account the severity and implications of coagulation complications.

LEVEL OF EVIDENCE

Level III.

Recommended primary outcomes for clinical trials evaluating hemostatic blood products and agents in patients with bleeding: Proceedings of a National Heart Lung and Blood Institute and US Department of Defense Consensus Conference

ABSTRACT

High-quality evidence guiding optimal transfusion and other supportive therapies to reduce bleeding is needed to improve outcomes for patients with either severe bleeding or hemostatic disorders that are associated with poor outcomes. Alongside challenges in performing high-quality clinical trials in patient populations who are at risk of bleeding or who are actively bleeding, the interpretation of research evaluating hemostatic agents has been limited by inconsistency in the choice of primary trial outcomes. This lack of standardization of primary endpoints or outcomes decreases the ability of clinicians to assess the validity of endpoints and compare research results across studies, impairs meta-analytic efforts, and, ultimately, delays the translation of research results into clinical practice. To address this challenge, an international panel of experts was convened by the National Heart Lung and Blood Institute and the US Department of Defense on September 23 and 24, 2019, to develop expert opinion, consensus-based recommendations for primary clinical trial outcomes for pivotal trials in pediatric and adult patients with six categories in various clinical settings. This publication documents the conference proceedings from the workshop funded by the National Heart Lung and Blood Institute and the US Department of Defense that consolidated expert opinion regarding clinically meaningful outcomes across a wide range of disciplines to provide guidance for outcomes of future trials of hemostatic products and agents for patients with active bleeding.

Bivalirudin May Reduce the Need for Red Blood Cell Transfusion in Pediatric Cardiac Patients on Extracorporeal Membrane Oxygenation

We retrospectively compared anticoagulation with heparin and bivalirudin for 32 consecutive children under 18 years old during extracorporeal membrane oxygenation (ECMO) in our pediatric cardiac intensive care unit (PCICU). Between September 2015 and January 2018, 14 patients received heparin, 13 venoarterial (VA), and 1 venovenous (VV). From February 2018 to September 2019, 18 received bivalirudin (all VA). The mean (standard deviation [SD]) percentage of time with therapeutic activated partial thromboplastin time and activated clotting time was bivalirudin 54 (14%) and heparin 57 (11%), p = 0.4647, and percentage of time supratherapeutic was bivalirudin 18 (10%) and heparin 27 (12%), p = 0.0238. Phlebotomy-associated blood loss per hour of ECMO was double in the heparin compared with bivalirudin group 1.08 ml/h (0.20 ml/h), compared with 0.51 ml/h (0.07 ml/h), p = 0.0003, as well as interventions to control bleeding. Packed red blood cell (PRBC) transfusions significantly correlated with higher blood loss in the heparin group (Pearson correlation coefficient = 0.49, p = 0.0047). Overall amount of blood product utilization was not different between the groups. Survival to ECMO decannulation was 89% for bivalirudin and 57% for heparin, p = 0.0396, although 6 month survival was not significantly different (67% versus 57%, p = 0.5809). Heparin may increase the need for PRBC transfusions and strategies to attenuate bleeding when compared with bivalirudin for children receiving ECMO in PCICU.

Use of rotational thromboelastometry to predict hemostatic complications in pediatric patients undergoing extracorporeal membrane oxygenation: A retrospective cohort study

BACKGROUND

The incidence of hemostatic complications in pediatric patients undergoing extracorporeal membrane oxygenation (ECMO) is high. The optimal anticoagulation strategy in children undergoing ECMO is unknown.

OBJECTIVES

To study the association between hemostatic complications, coagulation tests, and clinical parameters in pediatric patients undergoing ECMO and their effect on survival.

METHODS

We performed a retrospective cohort study of pediatric patients undergoing centrifugal pump ECMO. Collected data included patient characteristics, risk factors, and coagulation test results. Statistical analysis was done using logistic regression analysis for repeated measurements. Dependent variables were thrombosis and bleeding, independent variables were rotational thromboelastometry (ROTEM), activated partial thromboplastin time (aPTT) and antifactor-Xa assay (aXa) results, ECMO duration, age <29 days, sepsis and surgery.

RESULTS

Seventy-three patients with 623 ECMO days were included. Cumulative incidences of thrombosis and bleeding were 43.5% (95% confidence interval [CI], 26.0%-59.8%) and 25.4% (95% CI, 13.4%-39.3%), respectively. A lower maximum clot firmness of intrinsic ROTEM (INTEM; odds ratio [OR], 0.946; 95% CI, 0.920-0.969), extrinsic ROTEM (OR, 0.945; 95% CI, 0.912-0.973), and INTEM with heparinase (OR, 0.936; 95% CI, 0.896-0.968); higher activated partial thromboplastin time aPTT; OR, 1.020; 95% CI, 1.006-1.024) and age <29 days (OR, 2.900; 95% CI, 1.282-6.694); surgery (OR, 4.426; 95% CI, 1.543-12.694); and longer ECMO duration (OR, 1.149; 95% CI, 1.022-1.292) significantly increased thrombotic risk. Surgery (OR, 2.698; 95% CI, 1.543-12.694) and age <29 days (OR 2.242, 95% CI 1.282-6.694) were significantly associated with major bleeding. Patients with hemostatic complications had significantly decreased survival to hospital discharge (P = .009).

CONCLUSION

The results of this study help elucidate the role of ROTEM, aPTT, anti-factor Xa, and clinical risk factors in predicting hemostatic complications in pediatric patients undergoing ECMO.