17th July 2014  The CESAR Study

Presented By Dr Rita Bertuetti

In the last few months we have referred five trauma patients for ECMO at Papworth. These were all referred for respiratory failure and consideration of VV-ECMO. Awareness, and indeed use, of VV-ECMO has increased substantially since the 2009 H1N1 pandemic.

This week’s paper, the CESAR study (associated editorial), is possibly going to be the only large RCT on ECMO for respiratory failure. The worldwide experience gained during H1N1 has changed the therapeutic landscape so much that it is hard to see that the questions CESAR tried to address still apply, isn’t it? Would we, or any other ICU, ever never need to send someone to Papworth to make sure they got protective lung ventilation and diuretics?

It is very easy to be bewitched by VV-ECMO. It is absolutely wonderful, you start with a hypoxic, hypercarbic, acidotic patient being ventilated to death and after a 30 minute percutaneous procedure you reverse all of the physiological derangements while simultaneously removing iatrogenic harm from ventilation. Moreover, if you think that VV-ECMO is exciting wait until you see a new mum turn up to ED near arrest with a peripartum cardiomyopathy and go on to VA-ECMO as a bridge to LVAD to then go home and wait for transplant, it is not surprising that the national newspapers have taken an interest.

It is probably exactly this attraction which should force us to think very carefully every time we refer for ECMO. The data we have, in the UK at least, suggests that ECMO is safe and associated with better outcomes than conventional ventilation for isolated respiratory failure but trauma patients rarely have isolated respiratory failure.

In common with many of the studies we have discussed recently, CESAR does not really tell us what to do with trauma patients. Indeed there is legitimate debate about the utility of ECMO in patients with respiratory failure following trauma. This is perhaps where we need to focus our efforts – working out where ECMO sits in the trajectory of trauma intensive care medicine.

Broadly, there are three groups of trauma patients with respiratory failure:

1. TBI patients who have developed neurogenic cardio-respiratory failure – a complex process including stress induced cardiomyopathy and neurogenic pulmonary oedema.

2. Patients who have developed a trauma associated thoracic syndrome which includes contusions but also involves an ARDS-type process, TRALI, fluid overload and cardiac dysfunction.

3. Perhaps the simplest group are the patients who develop isolated respiratory failure due to infection, in complex trauma these are probably very rare cases.

This is almost certainly an over simplification but we do not really have any good guides about when to initiate ECMO in these groups. It is almost certain that the decisions are different between these groups. We also wonder whether the triggers, especially in TBI, should be set at a lower threshold than for isolated respiratory failure given the profound interactions between the brain, heart and lungs. It is these questions which set the challenges for us and Papworth to tease out over the next few years.

Looking to the future, however, we probably need to ask whether it is sensible to move TBI patients from neurocritical care units to cardiothoracic ICUs to permit ECMO when this takes patients away from neurosurgeons, neuroradiologists, and multimodal neuromonitoring. Co-localisation is clearly the optimal answer but this will be a long time in coming in many parts of the UK.

How should we address this?

What about patients at risk of haemorrhage, for example unfixed pelvic fractures?

There is a wealth of information about ECMO on the internet, some links are below. As a tangental issue, It is also interesting to see that mechanical cardiac support in the form of venous-arterial-ECMO is also rapidly moving from a peri-operative rescue therapy for heart failure to a first line treatment for cardiac arrest (ECMO-CPR).

Our friends in Papworth have written a good primer to all of the issues surrounding the various forms of ECMO while Guy Glover and colleagues in London have recently described the post-H1N1 ECMO services in England.

This cohort study from France and associated editorial illustrate the current state of the evidence.

An nice editorial on CESAR which is interesting because it was written after CESAR was published but before the full effect of the H1N1 was felt around the world. This editorial also demonstrates the historical journey ECMO has taken which has only accelerated post-H1N1.

NEJM review.

A recent, comprehensive review in Critical Care and some guidelines from France.

Current Opinion in Critical Care review of the evidence following the H1N1 pandemic.

Critical Care Journal Club on CESAR.

The Bottom Line on CESAR.