Acute oxygenator failure: a new presentation of heparin-induced thrombocytopenia in a patient undergoing venovenous extracorporeal membrane oxygenation support

Improving ECMO therapy: Monitoring oxygenator functionality and identifying key indicators, factors, and considerations for changeout

INTRODUCTION

The optimal timing for extracorporeal membrane oxygenation (ECMO) circuit change-out is crucial for the successful management of patients with severe cardiopulmonary failure. This comprehensive review examines the various factors that influence the timing of oxygenator replacement in the ECMO circuit. By considering these factors, clinicians can make informed decisions to ensure timely and effective change-out, enhancing patient outcomes and optimizing the delivery of ECMO therapy.

METHODOLOGY

A thorough search of relevant studies on ECMO circuits and oxygenator change-out was conducted using multiple scholarly databases and relevant keywords. Studies published between 2017 and 2023 were included, resulting in 40 studies that met the inclusion criteria.

DISCUSSION

Thrombosis within the membrane oxygenator and its impact on dysfunction were identified as significant contributors, highlighting the importance of monitoring coagulation parameters and gas exchange. Several factors, including fibrinogen levels, pre and post-membrane blood gases, plasma-free hemoglobin, D-dimers, platelet function, flows and pressures, and anticoagulation strategy, were found to be important considerations when determining the need for an oxygenator or circuit change-out. The involvement of a multidisciplinary team and thorough preparation were also highlighted as crucial aspects of this process.

CONCLUSION

In conclusion, managing circuit change-outs in ECMO therapy requires considering factors such as fibrinogen levels, blood gases, plasma-free hemoglobin, D-dimers, platelet function, flows, pressures, and anticoagulation strategy. Monitoring these parameters allows for early detection of issues, timely interventions, and optimized ECMO therapy. Standardized protocols, personalized anticoagulation approaches, and non-invasive monitoring techniques can improve the safety and effectiveness of circuit change-outs. Further research and collaboration are needed to advance ECMO management and enhance patient outcomes.

Propofol Safety in Anticoagulated and Nonanticoagulated Patients During Extracorporeal Membrane Oxygenation

Sedation management during extracorporeal membrane oxygenation(ECMO) is a common challenge encountered by treating intensivists. Data about the safety of propofol use during ECMO has been contradictory. We aimed to investigate associated risks of propofol use on oxygenator lifespan and to explore the effect of propofol use on oxygenator membranes when therapeutic anticoagulation was omitted. Adult respiratory ECMO patients who received propofol were retrospectively compared with those who did not, and outcomes were assessed by means of duration of oxygenator functionality before requiring an exchange, and number of exchanges during propofol use and/or ECMO support. Out of the 63patients included in the analysis, 46%received propofol during ECMO as part of sedation regimen. The use of propofol was not found to be associated with an increased incidence of oxygenator failure when compared with cohorts who did not receive propofol (21% propofol arm vs. 6% control, p = 0.13). When analyzed for anticoagulation omission effects, propofol did not increase the risk of oxygenator failure (p = 0.63). The only predictor that statistically predicted the risk of oxygenator failure was development of heparin-induced thrombocytopenia (HIT) during ECMO. The results of this study further support the previously reported safety of propofol utilization during respiratory ECMO even in the absence of anticoagulation.

The clinical correlates of vaccine-induced immune thrombotic thrombocytopenia after immunisation with adenovirus vector-based SARS-CoV-2 vaccines

We are at a critical stage in the COVID-19 pandemic where vaccinations are being rolled out globally, in a race against time to get ahead of the SARS-CoV-2 coronavirus and the emergence of more highly transmissible variants. A range of vaccines have been created and received either emergency approval or full licensure. To attain the upper hand, maximum vaccine synthesis, deployment, and uptake as rapidly as possible is essential. However, vaccine uptake, particularly in younger adults is dropping, at least in part fuelled by reports of rare complications associated with specific vaccines. This review considers how vaccination with adenovirus vector-based vaccines against the SARS-CoV-2 coronavirus might cause rare cases of thrombosis and thrombocytopenia in some recipients. A thorough understanding of the underlying cellular and molecular mechanisms that mediate this syndrome may help to identify methods to prevent these very rare, but serious side effects. This will also help facilitate the identification of those at highest risk from these outcomes, so that we can work towards a stratified approach to vaccine deployment to mitigate these risks.

Suspected heparin-induced thrombocytopenia in a COVID-19 patient on extracorporeal membrane oxygenation support: a case report

Background

Extracorporeal membrane oxygenation (ECMO) support can be life-saving in critically ill COVID-19 patients. However, there are many complications associated with this procedure, including Heparin-induced thrombocytopenia (HIT.) Despite its rarity in ECMO cases, HIT can lead to devastating consequences and is difficult to manage.

Case presentation

In this report, we present a case of a COVID-19 patient on ECMO support who was diagnosed with HIT and required intensive treatment. Initially, HIT was only suspected due to newly-developed thrombocytopenia and oxygenator dysfunction, with thrombi observed later. Regarding his treatment, since there was no recommended replacement to heparin available to us at the time of diagnosis, we decided to use rivaroxaban temporarily. No adverse events were recorded during that period. The patient was able to make a full recovery.

Conclusion

HIT may jeopardize patient’s care during ECMO. As COVID-19 may bring about a surge in the number of patients requiring ECMO support, we need consented guidance to optimize treatment in this specific situation.

Acute renal failure due to bilateral renal vein thromboses: A rare complication of heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia type II is a rare but devastating complication of heparin exposure. We review a case of a 66-year-old female who underwent aortic valve surgery requiring venoarterial extracorporeal membranous oxygenation (ECMO) support postoperatively. She subsequently developed acute renal failure due to bilateral renal vein thromboses and thrombocytopenia and was found to have platelet factor 4/heparin antibodies and was diagnosed with heparin-induced thrombocytopenia (HIT). She was transitioned to nonheparin anticoagulation and her thrombocytopenia improved. Although a rare complication of anticoagulation, diagnosing HIT in a patient on ECMO requires a high index of suspicion and should be considered.

Anticoagulation with direct thrombin inhibitors during extracorporeal membrane oxygenation

Use of extracorporeal membrane oxygenation to support patients with critical cardiorespiratory illness is increasing. Systemic anticoagulation is an essential element in the care of extracorporeal membrane oxygenation patients. While unfractionated heparin is the most commonly used agent, unfractionated heparin is associated with several unique complications that can be catastrophic in critically ill patients, including heparin-induced thrombocytopenia and acquired antithrombin deficiency. These complications can result in thrombotic events and subtherapeutic anticoagulation. Direct thrombin inhibitors (DTIs) are emerging as alternative anticoagulants in patients supported by extracorporeal membrane oxygenation. Increasing evidence supports DTIs use as safe and effective in extracorporeal membrane oxygenation patients with and without heparin-induced thrombocytopenia. This review outlines the pharmacology, dosing strategies and available protocols, monitoring parameters, and special use considerations for all available DTIs in extracorporeal membrane oxygenation patients. The advantages and disadvantages of DTIs in extracorporeal membrane oxygenation relative to unfractionated heparin will be described.

Heparin-induced thrombocytopenia during extracorporeal life support: incidence, management and outcomes

Background

Heparin-induced thrombocytopenia (HIT) is a severe antibody-mediated reaction leading to transient prothrombosis. However, its incidence in patients on extracorporeal life support (ECLS) is not well described. The aim of this systematic review was to report the incidence of HIT in patients on ECLS, as well as compare the characteristics and outcomes of HIT in patients undergoing veno-arterial extracorporeal membrane oxygenation (VA-ECMO) and veno-venous ECMO (VV-ECMO).

Methods

An electronic search was performed to identify all studies in the English literature examining outcomes of patients with HIT on ECLS. All identified articles were systematically assessed using specific inclusion and exclusion criteria. Random effects meta-analysis as well as univariate analysis was performed.

Results

Of 309 patients from six retrospective studies undergoing ECLS, 83% were suspected, and 17% were confirmed to have HIT. Due to the sparsity of relevant retrospective data regarding patients with confirmed HIT on ECLS, patient-based data was subsequently collected on 28 patients from case reports and case series. Out of these 28 patients, 53.6% and 46.4% of them underwent VA-ECMO and VV-ECMO, respectively. Patients on VA-ECMO had a lower median platelet count nadir (VA-ECMO: 26.0 vs. VV-ECMO: 45.0 per µL, P=0.012) and were more likely to experience arterial thromboembolism (VA-ECMO: 53.3% vs. VV-ECMO: 0.0%, P=0.007), though there was a trend towards decreased likelihood of experiencing ECLS circuit oxygenator thromboembolism (VA-ECMO: 0.0% vs. VV-ECMO: 30.8%, P=0.075) and thromboembolism necessitating ECLS device or circuit exchange (VA-ECMO: 13.3% vs. VV-ECMO 53.8%, P=0.060). Kaplan-Meier survival plots including time from ECLS initiation reveal no significant differences in survival in patients supported on VA-ECMO as compared to VV-ECMO (P=0.300).

Conclusions

Patients who develop HIT on VA-ECMO are more likely to experience more severe thrombocytopenia and arterial thromboembolism than those on VV-ECMO. Further research in this area and development of standardized protocols for the monitoring, diagnosis and management of HIT in patients on ECLS support are warranted.