Everything ECMO – Part One

Most of the following post is taken from the recent Sydney HEMS ECMO Education day with some taken from an earlier ECMO education day and amalgamated into a huge amount of notes.

ECMO in New South Wales

Associate Professor Paul Forrest, a Cardiothoracic Anaesthetist and ECMO Specialist from RPA Hospital kicked off the day with an overview of the evolution and current state of ECMO services in NSW. He has a full uploaded presentation here you might be interested in or you can watch the full video below.

There are agreed statewide indications for ECMO – clicking on the link will take you to the document.

How does it work in NSW?

Who goes on the mission?

  • ECMO team: Surgeon/anaesthetist or intensivist, medical perfusionist +/- technician
  • Retrieval team: Doctor and paramedic/nurse

Where do patients go for ECMO?

Patients are routed to St Vincent or RPA as per the Medical Retrieval Unit who oversees the mission.

When did the service start?

The initial service commenced prior to the H1N1 outbreak – this paper in JAMA Oct 12 2009 describes how the service was utilised during the outbreak. 68 patients were treated with ECMO for a median of 10 days (IQR 7-15 days) with 48 surviving to ICU discharge (32 to hospital discharge, 16 still inpatients) at the time of publication.

How is ECMO undertaken during retrieval?

The Cardiohelp pump is used with a customised footplate. When an ECMO team is tasked for a retrieval mission, the team will come with four custom packed retrieval packs of their own.

58% of ECMO transfers are transported by road, 27% by fixed wing and 15% by helicopter.

How successful is ECMO in NSW?

Feb 2016 figures: 68% survival to discharge overall, 72% in resp subgroup and 60% for cardiac subgroup

LearnECMO: Sean Scott & the St Vincent Team

The St Vincent’s team, headed up by the wonderful Sean Scott,  joined us for an ECMO themed sim. Learning was centred around an interactive simulation, the retrieval of a 55 year old patient from a smaller hospital in conjunction with the ECMO team.

Our role in these missions as the retrieval team: to take care of the patient, while the ECMO team takes care of the ECMO machine and pipes (“it’s not about the plumbing”). The full talk is shown in the video below.

ECMO Basics

The Two Types of ECMO

ECMO is basically a heart and a lung – a pump and an oxygenator. Where you plug in the pipes determines the sort of support you (the patient) get(s).

VV – oxygenation, no cardiovascular support

VA – also generates a blood pressure, essentially a cardiopulmonary bypass machine

We should consider ECMO as a bridge; generally it is used as a bridge to recovery but sometimes to a decision (further resuscitation? Transplant?) or definitive intervention (treatment of cause of cardiac arrest).

Why (when) VV?

This is effectively lung bypass, used when the “lungs don’t work” – there are many causes, for example:

  • ARDS
  • Airway problems (can’t be intubated eg airway injury)
  • Bad asthma

Needs to be a potentially reversible cause

Why (when) VA?

This is effectively heart and lung bypass, used for support in circulatory failure – cardiogenic shock is the most common/obvious reason (although the underlying cause may be MI, overdose etc.)

Trauma? – has been used in hypotensive trauma patients

Sepsis? – jury is out on whether this is a good idea (how reversible are the processes involved?)!

How does it work?

Most common is femoral/femoral VV cannulation

Fem/fem – two cannulae in IVC, one draining and one returning – can’t use two multistage cannulae (recirculation – when blood doesn’t actually flow through the circulation – is very high)

Fem/jug placement avoids this

What about in Cardiac Arrest?

Now features in the 2015 ALS guidelines under “consider” (extracorporeal CPR)

2CHEER (the study into LUCAS plus ECMO for out-of-hospital VF arrest) is ongoing in Sydney

However, it doesn’t “consider” all the logistical work involved in getting people onto ECPR

ECPR means we should add a few new links to the chain of survival – mechanical CPR on scene, ECMO in ED, straight to cath lab

Common patient scenario – refractory VF, PEA or asystole but after ECMO perfuses the coronaries, ROSC may occur quickly.

ECMO remains on after ROSC (the flow may be dropped a little) – the patient is usually in cardiogenic shock so needs the ongoing support.

How has ECPR been achieved?

Pit crew concept – everyone has defined roles, printed on role cards which they wear

This video shows how this is trained for through simulation.

LUCAS is used as a bridge to ECMO, ECMO is used as a bridge to intervention.

The target of ECPR is maintenance of cerebral perfusion while reversible causes are addressed.

Prehospital Training for 2CHEER was key, with a strong focus on changing the dynamics of arrest calls.

Put LUCAS on early, decision for eligibility early, transport early (with definitive airway if possible)

BatPhone activation to the ECMO centre is essential for team preparation

Clear role development and allocation with role cards (A5)

This training is not particularly frequent – one a month or so – which is helpful for refreshing and framing behaviour.

Should everyone get ECPR?!

No! There are STOP criteria – although in practical terms it is advised that processes continue until there is a reason to stop

  • >70yrs
  • Unwitnessed
  • >10mins without BLS
  • >60mins since collapse
  • Initial rhythm asystole
  • Organ failure or malignancy
  • No prospect of reversal

How do you echo with all this going on?

Transoesophageal Echo is used to guide cannula placement

There is a strict 90mins cutoff – if the patient has not been (ECMO) cannulated by 90mins from arrest time, efforts should stop (in reality this means the patients need to arrive in ED at 60mins from arrest time). No cases in the Sydney registry have not achieved this as yet!

Anticoagulation/Antiplatelets and Clots

5,000 units of heparin are given when the cannnulae go in. An extra (approx.) 7,000 units are given with the pump (which is primed with 10,000 units, there is some loss during connection).

The venous line is connected first due to risk of clots – they would then be sucked into unit, not into brain (as would occur if arterial line placed first).

What if the cause of arrest is a SAH?

VF arrests can occur with SAH – 15-20% of patients on ECMO end up with ICH (pre or resultant), CT brain is deferred until after definitive cardiac intervention, which may be >24h.

What about for massive PE?

The team aims to get the patient onto ECMO on then thrombolyse – there is a potential for catheter directed lysis. Half dose used thrombolysis has been used as per MOPETT until now but radiology support for catheter directed is now available.

Who is suitable for eCPR after out-of-hospital arrest?

  • Patients <65
  • Witnessed VF arrest
  • Bystander CPR

In-hospital, the team might be more lenient with rhythm (but would still need to know there’s a reversible cause)

Who is not suitable?

  • Elderly
  • Comorbidities e.g. liver, renal failure, severe respiratory disease
  • Advanced malignancies
  • Advanced care directive
  • See STOP criteria

What are the common complications?

Usually complications occurring immediately are related to cannulation – bleeding, haematoma, kinked wires, femoral nerve damage, arterial injury.

In standard elective VA ECMO, clinicians would put in a backflow cannula from arterial cannula to perfuse the distal limb. Smaller cannulae are used in ECPR to facilitate distal perfusion; after angiography, a backflow cannula is sited.

Longer term complications include: bleeding/clotting, infection plus the complications of a long ICU stay

Making ECPR happen in the Emergency Department

What happens in the Precannulation phase?

(this is essentially a checklist for the ED Consultant)

  • High quality CPR
  • LUCAS
  • Airway secure
  • EtCO2
  • Expose and shave groins
  • IV access
  • Cath lab aware

What happens in the Cannulation phase?

Can stop LUCAS but priority is excellent ongoing CPR

Defibrillation is not necessary during the cannulation phase

What happens Post-Cannulation?

  • Stop LUCAS
  • Defibrillate (three shocks max)
  • Get ejection fraction from echo
  • Expedite transfer to cath lab

Cannulation issues

Immediate term: difficulty getting access, wrong vessels (VV in arrest, AA), haematoma formation – surgical backup (for cutdown) and TOE confirmation can be helpful

Checklists are available and helpful e.g. suck down (insufficient volume to fill venous drainage cannula) – see more info in part two

What’s the Evidence for all this?

It’s not awesome as yet – there are not many RCTs.

The paper by Kim et al in Resuscitation (2012) was a review comparing conventional care with ECMO – suggests better neurologically intact survival

CHEER

(CPR, hypothermia, ECMO and early reperfusion)

This study took place in Melbourne (hypothermia was dropped) – there’s a great review of this paper over at The Bottom Line.

CESAR

(Conventional ventilator support vs ECMO for Severe Adult Respiratory Failure)

This study looked at the benefits of referral to and treatment in an ECMO centre – the authors found a survival benefit with NNT 7

Notably although 90 were randomised to ECMO, only 70 went onto ECMO

You can find another great review over at the Bottom Line.

Where can I find out more?

On ECMO

LearnECMO.com

Loads of resources over at IntensiveCareNetwork.com

ED ECMO

On the literature

ECMO literature summaries – Life in the Fast Lane

About Natalie May

EM and PEM-trained UK doctor working in Prehospital & Retrieval Medicine in Australia. Evolving medical education interest, running enthusiast, karaoke queen. Here for the #FOAMed.
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