Therapeutic monitoring of Anticoagulation on ECMO: A brief survey of UK practice Kate Howson Good afternoon. I’m one of the perfusionists at QE Hospital in Birmingham. I’m going to present the results of a short survey on anticoagulation on ECMO. I became interested in this topic after recently moving centres. I was a bit surprised by the different levels of perfusion involvement and I realised that some things I’d taken for granted (such as monitoring anti Xa levels) aren’t standard practice.

The Issue Mortality and morbidity still relatively high - haemorrhage and thromboembolic common contributory causes. Bleeding and coagulopathy the most frequent complication. Extremely complex management in a diverse group of patients. MDT approach, different levels of perfusion involvement. ELSO guidelines are broad. There is evidence that ECMO outcomes are getting better and have steadily improved, particularly over the past ten years following the experience of the H1N1 epidemic. In 2016 adult survival rates for respiratory ECMO reached 65%%. The improvement in outcomes is encouraging but adult mortality rates remain high. Haemorrhage and thromboembolic complications are one of the major causes of morbidity and mortality. Coagulopathy and bleeding are the most common ECMO complication. These factors are significant and mean it’s critical that we think about how we are managing anticoagulation. We don’t really know what the optimum method of monitoring anticoagulation is, a short survey can’t hope to answer that question. But I was interested in finding out what we are doing across the UK and seeing what the most common approaches are. I used the ELSO guidelines as a framework for this.

ELSO Guidelines 1. Activated Clotting Time (ACT) 2. Anti-Factor Xa Activity Levels (Anti-Xa) 3. Activated Partial Thromboplastin Time (APTT) 4. Thromboelastography (TEG) 5. Thromboelastometry (ROTEM) The Extracorporeal Life Support Organization guidelines recommend using these five tests. They acknowledge that it’s not practical to run all of these tests all of the time and but suggests that at least two or three of them are optimum practice.

Results 24 responses received 5 centres did not perform ECMO 15 centres were performing more than 5 annual ECMO runs 10 identified as respiratory centres Valerie very kindly emailed this survey to every cardiac centre and the response rate was 50%. I think this may reflects the limited ECMO experience of some centres. Of respondents 19 centres are performing ECMO, the majority of these were performing more than five runs a year. 10 respiratory centres replied.

Perfusion So how involved are we in monitoring? Almost half of respondents described limited involvement, over a third were very engaged – describing their involvement as regular or substantial. The three centres that reported no involvement were in the minority.

The Circuit The responses to this were quite evenly split but the majority reported no heparin coating.

Protocols We’re actually very organised here and almost everyone has a protocol and a separate bleeding protocol in place.

ACT monitoring Only two centres doesn’t use ACT monitoring, which surprised me a little bit. Of those that do one centre describes using a mixture of low and high range and one high range.

Tests used The majority of centres are using fibrinogen levels, platelet counts, Anti-Factor Xa and APPT. Around half are using TEG and only one ROTEM. Almost 40% are measuring D-Dimer levels, which I’m particularly interested in as we’ve just started monitoring this.

Test frequency: Not Bleeding

Test Frequency: Bleeding   

Conclusion The majority of centres are involved and consulted at least occasionally. No neat ideal practice – adaptable to circumstances. Following ELSO guidelines, lower uptake of anti Xa (53%). D-Dimer levels an interesting supplementary test used by 37% of respondents. The vast majority of us are involved in this in some capacity. Of course each of these tests has important limitations and it is important to recognise that the diversity of the patients mean that a test appropriate for one circumstance may not translate to another, for example respiratory patients and post cardiotomy patients are very different.

And Finally… Many thanks to everyone who took the time to respond to this survey. Finally I would like to thank everyone who took the time to respond and complete this survery. I’m very grateful for your time.

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