Catheter directed thrombolysis for a pulmonary arterial thrombus on VA ECMO in a child - a case report

INTRODUCTION

Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) as a bridge to cardiac transplantation is considered a high risk support strategy in the paediatric population.

METHODS

We describe the case of a 12 year old boy who required V-A ECMO support for rapidly deteriorating cardiomyopathy and developed a massive pulmonary embolus (PE) peri-cannulation. Subsequent investigations were also positive for heparin induced thrombocytopenia.

RESULTS

We elected to treat the PE with ultrasound accelerated catheter directed thrombolysis using the advantages of this minimally invasive targeted method to try and resolve the PE and avoid a cerebral haemorrhage, both of which would have taken the patient off the urgent transplant list.

CONCLUSION

The PE resolved in 24 h and he went on to receive a cardiac transplant and have a favourable outcome.

Review of anticoagulation considerations in extracorporeal membrane oxygenation support

Since its first success in 1975, extracorporeal membrane oxygenation (ECMO) has been used with increasing frequency for pulmonary and cardiopulmonary bypass. Use in adults has increased exponentially since the early 2000s, but despite thousands of international cannulations using both veno-arterial (VA) and veno-venous (VV) ECMO, there are still significant hemocompatibility-related adverse events. Current management of anticoagulation has been based on the Extracorporeal Life Support Organization guidance published in 2014 with recent updates published in 2022. Despite this guidance, there is still limited international consensus on how to manage anticoagulation in ECMO. For this review, we completed a comprehensive search of multiple electronic databases to identify studies pertaining to anticoagulation of adult patients on VV or VA-ECMO. The highest priority was given to sources that were prospective, randomized, controlled studies, but in the absence of such resources, observational studies, retrospective uncontrolled studies, and case series/reports were considered for inclusion. This document serves to provide a comprehensive review of the current understanding of management pertaining to anticoagulation relating to ECMO.

Prevalence and outcomes of patients developing heparin-induced thrombocytopenia during extracorporeal membrane oxygenation

Objectives

Unfractionated heparin (UFH) is the commonly used anticoagulant to prevent clotting of the ECMO circuit and thrombosis of the cannulated vessels. A side effect of UFH is heparin-induced thrombocytopenia (HIT). Little is known about HIT during ECMO and the impact of changing anticoagulation in ECMO patients with newly diagnosed HIT. The aim of the study was to determine the prevalence, complications, impact of switching anticoagulation to argatroban and outcomes of patients developing heparin-induced thrombocytopenia (HIT) during either veno-venous (VV) or veno-arterial (VA) ECMO.

Methods

Retrospective observational single centre study of prospectively collected data of consecutive patients receiving VV ECMO therapy for severe respiratory failure and VA ECMO for circulatory failure from January 2006 to December 2016 of the Medical intensive care unit (ICU) of the University Hospital of Regensburg. Treatment of HIT on ECMO was done with argatroban.

Results

507 patients requiring ECMO were included. Further HIT-diagnostic was conducted if HIT-4T-score was ≥4. The HIT-confirmed group had positive HIT-enzyme-linked-immunosorbent-assay (ELISA) and positive heparin-induced-platelet-activation (HIPA) test, the HIT-suspicion group a positive HIT-ELISA and missing HIPA but remained on alternative anticoagulation until discharge and the HIT-excluded group a negative or positive HIT-ELISA, however negative HIPA. These were compared to group ECMO-control without any HIT suspicion. The prevalence of HIT-confirmed was 3.2%, of HIT-suspicion 2.0% and HIT-excluded 10.8%. Confirmed HIT was trendwise more frequent in VV than in VA (3.9 vs. 1.7% p = 0.173). Compared to the ECMO control group, patients with confirmed HIT were longer on ECMO (median 13 vs. 8 days, p = 0.002). Different types of complications were higher in the HIT-confirmed than in the ECMO-control group, but in-hospital mortality was not different (31% vs. 41%, p = 0.804).

Conclusion

HIT is rare on ECMO, should be suspected, if platelets are decreasing, but seems not to increase mortality if treated promptly.

HEROES V-V-HEmorRhagic cOmplications in Veno-Venous Extracorporeal life Support-Development and internal validation of multivariable prediction model in adult patients

BACKGROUND

During extracorporeal life support (ECLS), bleeding is one of the most frequent complications, associated with high morbidity and increased mortality, despite continuous improvements in devices and patient care. Risk factors for bleeding complications in veno-venous (V-V) ECLS applied for respiratory support have been poorly investigated. We aim to develop and internally validate a prediction model to calculate the risk for bleeding complications in adult patients receiving V-V ECLS support.

METHODS

Data from adult patients reported to the extracorporeal life support organization (ELSO) registry between the years 2010 and 2020 were analyzed. The primary outcome was bleeding complications recorded during V-V ECLS. Multivariable logistic regression with backward stepwise elimination was used to develop the predictive model. The performance of the model was tested by discriminative ability and calibration with receiver operating characteristic curves and visual inspection of the calibration plot.

RESULTS

In total, 18 658 adult patients were included, of which 3 933 (21.1%) developed bleeding complications. The prediction model showed a prediction of bleeding complications with an AUC of 0.63. Pre-ECLS arrest, surgical cannulation, lactate, pO₂ , HCO₃ , ventilation rate, mean airway pressure, pre-ECLS cardiopulmonary bypass or renal replacement therapy, pre-ECLS surgical interventions, and different types of diagnosis were included in the prediction model.

CONCLUSIONS

The model is based on the largest cohort of V-V ECLS patients and reveals the most favorable predictive value addressing bleeding events given the predictors that are feasible and when compared to the current literature. This model will help identify patients at risk of bleeding complications, and decision making in terms of anticoagulation and hemostatic management.

New Trends, Advantages and Disadvantages in Anticoagulation and Coating Methods Used in Extracorporeal Life Support Devices

The use of extracorporeal life support (ECLS) devices has significantly increased in the last decades. Despite medical and technological advancements, a main challenge in the ECLS field remains the complex interaction between the human body, blood, and artificial materials. Indeed, blood exposure to artificial surfaces generates an unbalanced activation of the coagulation cascade, leading to hemorrhagic and thrombotic events. Over time, several anticoagulation and coatings methods have been introduced to address this problem. This narrative review summarizes trends, advantages, and disadvantages of anticoagulation and coating methods used in the ECLS field. Evidence was collected through a PubMed search and reference scanning. A group of experts was convened to openly discuss the retrieved references. Clinical practice in ECLS is still based on the large use of unfractionated heparin and, as an alternative in case of contraindications, nafamostat mesilate, bivalirudin, and argatroban. Other anticoagulation methods are under investigation, but none is about to enter the clinical routine. From an engineering point of view, material modifications have focused on commercially available biomimetic and biopassive surfaces and on the development of endothelialized surfaces. Biocompatible and bio-hybrid materials not requiring combined systemic anticoagulation should be the future goal, but intense efforts are still required to fulfill this purpose.

Heparin-induced thrombocytopenia in extra-corporeal membrane oxygenation: epidemiology, outcomes, and diagnostic challenges

To describe the prevalence of heparin-induced thrombocytopenia (HIT) in patients on extracorporeal membrane oxygenation (ECMO) and to explore ways to improve the diagnostic accuracy of the HIT enzyme-linked immunosorbent assay (ELISA). Retrospective review of all patients needing ECMO between September 2011 and September 2020 who underwent evaluation for HIT while on ECMO. The diagnosis of HIT required a confirmatory serotonin release assay (SRA). Various break points for the optical density (OD) that defines a positive HIT ELISA were examined to estimate their utility as screening tests for HIT. Patient outcomes served as a secondary endpoint. Among 417 ECMO patients, 162 (38.8%) had a HIT ELISA. Of these, 114 (70.4%) had a subsequent SRA. Although the HIT ELISA was positive at an OD ≥ 0.4 in 1/3^rd of subjects, only 15 subjects met criteria for HIT by SRA. Hence, the prevalence of HIT equaled 3.6%. At an OD ≥ 0.4 the ELISA had both poor specificity (71.7%) and accuracy (74.6%). Changing the definition of the ELISA to an OD ≥ 1.2 improved both specificity and accuracy with only a limited impact on sensitivity. Nearly 60% of those with HIT developing during ECMO died. HIT is infrequent in persons requiring ECMO. However, HIT remains associated with substantial mortality. The HIT ELISA as currently implemented performs poorly as a screening test and likely results in the unnecessary overuse of alternatives to unfractionated heparin. Altering the definition of a positive OD improves the HIT ELISA’s accuracy.

Analysis of the 2020 EACTS/ELSO/STS/AATS Expert Guidelines on the Management of Adult Postcardiotomy Extracorporeal Life Support

Extracorporeal life support (ECLS), also known as extracorporeal membrane oxygenation (ECMO), increasingly is used in postcardiotomy (PC) shock to facilitate a bridge to sustained recovery, long-term mechanical support, or heart transplantation. Given increasing prevalence and complexity of PC-ECLS, a joint expert consensus guideline was created in 2020 for management of adult PC-ECLS by the European Association for Cardio-Thoracic Surgery (EACTS), the Extracorporeal Life Support Organization (ELSO), the Society of Thoracic Surgeons (STS), and the American Association of Thoracic Surgery (AATS). The aim of this analysis was to comprehensively review the expert consensus guidelines, with particular emphasis on PC-ECLS candidacy, timing, cannula configuration, left ventricular distention, anticoagulation, ECLS weaning, and intensive care unit complications. This analysis finds the expert consensus guideline to be timely, pertinent, and clinically valuable, although there remains the need for larger clinical trials to codify best practices.

Frequency of Thrombocytopenia and Heparin-Induced Thrombocytopenia in Patients Receiving Extracorporeal Membrane Oxygenation Compared With Cardiopulmonary Bypass and the Limited Sensitivity of Pretest Probability Score

OBJECTIVES

To ascertain: 1) the frequency of thrombocytopenia and heparin-induced thrombocytopenia; 2) positive predictive value of the Pretest Probability Score in identifying heparin-induced thrombocytopenia; and 3) clinical outcome of heparin-induced thrombocytopenia in adult patients receiving venovenous- or venoarterial-extracorporeal membrane oxygenation, compared with cardiopulmonary bypass.

DESIGN

A single-center, retrospective, observational cohort study from January 2016 to April 2018.

SETTING

Tertiary referral center for cardiac and respiratory failure.

PATIENTS

Patients who received extracorporeal membrane oxygenation for more than 48 hours or had cardiopulmonary bypass during specified period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Clinical and laboratory data were collected retrospectively. Pretest Probability Score and heparin-induced thrombocytopenia testing results were collected prospectively. Mean age (± SD) of the extracorporeal membrane oxygenation and cardiopulmonary bypass cohorts was 45.4 (± 15.6) and 64.9 (± 13), respectively (p < 0.00001). Median duration of cardiopulmonary bypass was 4.6 hours (2-16.5 hr) compared with 170.4 hours (70-1,008 hr) on extracorporeal membrane oxygenation. Moderate and severe thrombocytopenia were more common in extracorporeal membrane oxygenation compared with cardiopulmonary bypass throughout (p < 0.0001). Thrombocytopenia increased in cardiopulmonary bypass patients on day 2 but was normal in 83% compared with 42.3% of extracorporeal membrane oxygenation patients at day 10. Patients on extracorporeal membrane oxygenation also followed a similar pattern of platelet recovery following cessation of extracorporeal membrane oxygenation. The frequency of heparin-induced thrombocytopenia in extracorporeal membrane oxygenation and cardiopulmonary bypass were 6.4% (19/298) and 0.6% (18/2,998), respectively (p < 0.0001). There was no difference in prevalence of heparin-induced thrombocytopenia in patients on venovenous-extracorporeal membrane oxygenation (8/156, 5.1%) versus venoarterial-extracorporeal membrane oxygenation (11/142, 7.7%) (p = 0.47). The positive predictive value of the Pretest Probability Score in identifying heparin-induced thrombocytopenia in patients post cardiopulmonary bypass and on extracorporeal membrane oxygenation was 56.25% (18/32) and 25% (15/60), respectively. Mortality was not different with (6/19, 31.6%) or without (89/279, 32.2%) heparin-induced thrombocytopenia in patients on extracorporeal membrane oxygenation (p = 0.79).

CONCLUSIONS

Thrombocytopenia is already common at extracorporeal membrane oxygenation initiation. Heparin-induced thrombocytopenia is more frequent in both venovenous- and venoarterial-extracorporeal membrane oxygenation compared with cardiopulmonary bypass. Positive predictive value of Pretest Probability Score in identifying heparin-induced thrombocytopenia was lower in extracorporeal membrane oxygenation patients. Heparin-induced thrombocytopenia had no effect on mortality.

Intraoperative collection of autologous platelet-rich plasma from the cardiopulmonary bypass circuit upon initiation of extracorporeal circulation

Objectives

The aim of this study is to evaluate the possibility of the autologous platelet-rich plasma (PRP) collection from the cardiopulmonary bypass (CPB) circuit and to evaluate its effect on the aggregative function.

Methods

For seventy-two patients undergoing cardiac surgery with CPB, an autologous PRP was prepared using the Haemonetics Component Collection System® by drawing blood from the CPB circuit immediately after CPB was established. The blood samples were taken at three points for examination, A: beginning of surgery, B: immediately after heparin reversal with protamine following discontinuation of CPB, C: after the collected autologous PRP was returned to the patient. Platelet count and platelet aggregation ability were analyzed.

Results

The mean platelet count in autologous PRP was 5.5 (range: 3–14) units. Platelet count decreased by 115.0 (±27.3) × 1000/μl from A to B and increased by 27.3 ± 17.2 (× 1000/μl) from B to C.

When platelet aggregation was measured by Adenosine Diphosphate (ADP) 3.0 μM, it decreased by 42.6% ± 12.1% from A to B and increased by 8.7% ± 7.4% from B to C.

Conclusions

Autologous PRP can be safely collected by drawing blood from the CPB circuit, platelet count and aggregation ability significantly decreased after CPB including autologous PRP collection. Some improvement was detected in the number of the platelets count and platelet aggregation ability by administrating an autologous PRP even if autologous PRP is collected from CPB circuit.

Trial registration

UMI-CTR, UMIN000023776. Registered 1 October 2016.

A narrative review of antithrombin use during veno-venous extracorporeal membrane oxygenation in adults: rationale, current use, effects on anticoagulation, and outcomes

BACKGROUND

During extracorporeal membrane oxygenation, the large contact surface between the blood and the extracorporeal circuit causes a continuous activation of coagulation and inflammation. Unfractionated heparin, a glycosaminoglycan that must bind to antithrombin as a cofactor, is currently the standard anticoagulant adopted during extracorporeal membrane oxygenation. Antithrombin, beyond being a potent natural anticoagulant, acts in the cross-talk between coagulation and inflammatory system through anticoagulation and coagulation-independent effects.

OBJECTIVES

In this review, we describe, in the adult setting of veno-venous extracorporeal membrane oxygenation, the pathophysiological rationale for antithrombin use, the current practice of administration, and the effects of antithrombin on anticoagulation, bleeding, and outcomes.

DATA SOURCES

Studies on adults (18 years or older) on veno-venous extracorporeal membrane oxygenation published from 1995 to 2018 in order to evaluate the use of antithrombin.

RESULTS

In adults on veno-venous extracorporeal membrane oxygenation, antithrombin supplementation has a highly pathophysiological rationale since coagulation factor consumption, systemic inflammatory response syndrome, and endothelial activation are triggered by extracorporeal membrane oxygenation. Eleven articles are focused on the topic but among the authors there is no consensus on the threshold for supplementation (ranging from 70% to 80%) as well as on the dose (rarely standardized) and time of administration (bolus vs continuous infusion). Consistently, antithrombin is considered able to achieve better anticoagulation targets in or not in the presence of heparin resistance. The impact of antithrombin administration on bleeding still shows contrasting results.

CONCLUSION

Antithrombin use in veno-venous extracorporeal membrane oxygenation should be investigated on the threshold for supplementation, dose, and time of administration.