Everything ECMO – Part Two

Natalie Kruit on Troubleshooting ECMO Retrieval

This second post from the Sydney HEMS ECMO education days summarises a great session by Retrieval Doctor and all-round legend Natalie Kruit on Troubleshooting in ECMO Retrieval.

What’s the role of the Retrieval Doctor?

As mentioned in Part One, the retrieval doctor is essentially there to look after the patient as a whole, while the separate ECMO team will oversee the function of the ECMO pump.

The first thing to know as a retrieval doctor is that the pump is primed with crystalloid – there is approx. 1L in circuit in total – so we should expect patients to be a bit unstable after transition onto pump!

VV ECMO

There is an access line in or near vena cava – this draws blood into the pump. This is the negative pressure part of the circuit.

Blood drains into centrifugal pump, is oxygenated and is returned to the right atrium.

VV ECMO inclusion criteria

The Murray score is used for this: for a score >3 – consider referral to ECMO centre

Murray score: VV ECMO inclusion criteria

Pathologies that will do well: asthma, ARDS. The longer they’ve been on a ventilator, the less likely they are to do well on ECMO.

What can you as the retrieval doctor do?

  • Optimise
  • Sedate and paralyse
  • Find best available vent
  • Recruit and PEEP
  • Diurese
  • HRCT
  • Right radial arterial line for sampling etc

Troubleshooting 1: Access Insufficiency

This occurs when the vein the cannula is sitting in is collapsing around the cannula.

  • Sucking down onto cannula
  • “Kicking” of the line
  • Fluctuating circuit flows

Causes: hypovolaemia, anything altering venous return (eg coughing, sedation bolus, increased abdominal pressures)

Treatments: drop the revs, give volume, remove obstruction, consider and exclude tamponade

Ventilation strategies on VV ECMO

Once on VV ECMO – target lung protective ventilation: rest the lungs, minimise alveolar strain

Reduce FiO2 (target around 0.6 if possible: O2 toxicity, diffusion atelectasis from reabsorption), reduce the RR, increase PEEP (prevent alveolar closing and opening – maintain alveolar opening), smaller TVs (4mls/kg or even lower) (letting the ECMO circuit do the oxygenation)

Troubleshooting 2: Bleeding on ECMO

Caused by

  • Fibrinolysis
  • Circuit driven fibrinolysis
  • Mucosal bleeding initially
  • Strong correlation with mortality
  • Heparin resistance

Targets: Platelets >50, Fibrinogen >1.0, INR <2.0, APTT 1.5x normal

If bleeding: TXA, FFP, platelets (prepare to do an ECMO circuit change as may clot) – don’t give protamine (you will get clots and that is maximum badness!

Troubleshooting 3: Hypoxia

When SpO2 increasing on ECMO machine, the patient becoming hypoxic – this suggests recirculation (blood not getting to the patient)

Shunting on VV ECMO

The circuit may not be able to capture full cardiac output, so some deoxygenated blood is circulating. Preferentially this seems to go to the brain and heart. This can happen in someone whose circulation is hyperdynamic (eg sepsis, morbid obesity). The drainage cannula is a good determinant of flow (a bigger drainage cannula gives better flows).

Cardiac output >ECMO flow (if you set flow at 5L/min and the patient is hyperdynamic at 10L/min, only half blood vol will be going through circuit and being oxygenated)

Treatment:

  • Increase ECMO flow (but you risk suckdown)
  • High flow configuration – consider a second access cannula (can add third access line in neck if in fem/fem configuration)
  • Increase O2 carrying capacity: transfuse if Hb is low
  • Check oxygenator (may be cause due to clots) – measure pre and post oxygenator O2. Look for delta P <50
  • Check for recirculation (see below)
  • Check ventilator settings

Troubleshooting 4: Recirculation

This occurs when the access line and drainage line are sitting too close together so the flow is bypassing patient altogether! Or if there is increased intrathoracic/intracardiac pressure (e.g. tamponade)

You may see a low arterial SaO2 and high access cannula SaO2.

Treatment:

  • CXR to check pipe position
  • Could withdraw appropriately to increase distance between drainage and return lines
  • Check for tamponade

VA ECMO

There are two different cannulation options for VA ECMO.

  • Central – directly cannulated via sternotomy
  • Peripheral – femoral vessels (blood from the femoral vein flows out to pump then back into femoral artery and pumped UP – this is non-physiological! Blood will be flowing against the normal flow direction – towards heart. This configuration needs a backflow cannula to ensure distal limb perfusion)

You’ll get some mixing of the deoxygenated blood from the ventricle with the oxygenated blood from the ECMO circuit – the more contractile the ventricle, the more distal the mixing point. There’s a nice interactive critical care case here that covers some of this.

If the lungs are not working and the heart is starting to recover and therefore has some recovering ejection fraction, the heart will preferentially eject to coronary and cerebral circulations (so check the ECG for signs of cardiac ischaemia) – it’s also helpful to have a  SpO2 probe on right hand to see differential hypoxia early.

Troubleshooting 1: Differential hypoxia (AKA harlequin syndrome)

In this scenario the heart is pumping (so there is a native cardiac output) and that is picking up and distributing deoxygenated blood that we can’t capture with ECMO flow. You may see demarcation of skin tone change across the trunk and/or the ECG may show ischaemic changes. There’s a nice diagram here which comes from this open access paper  in Circulation (clicking the link will download the PDF).

Treatment:

  • try to treat the lungs (eg bronchoscopy, increase the PEEP, add a venous catheter so some oxygenated blood is going to right heart)

Patient selection for VA ECMO

  • Patients unable to wean from bypass (post cardiotomy)
  • Awaiting heart transplant
  • RV failure
  • Overdose
  • AMI with multi-organ failure
  • Cardiomyopathy/myocarditis

When severe end organ damage  has occurred (e.g. AST/ALT very high, lactate >10 and not clearing) we have missed the boat!

Ventilation strategies on VA ECMO

We are aspiring to the least damaging lung ventilation

  • Maintain PEEP (aeration)
  • Measure SpO2 and PaO2 right arm
  • Minimise RV afterload and strain – avoid hypercapnia, hypoxia and complete lung collapse

Haemodynamic Management

  • Discuss haemodynamic goals with ECMO specialist
  • Inotropes to maintain ejection fraction
  • Maintain perfusion pressure for end organ perfusion
  • Promote forward flow: maintain MAP 65mmHg ideally (less than 90mmHg)

Troubleshooting 2: Loss of pulsatility

Causes:

  • Tamponade
  • Myocardial depression
  • LV failure
  • Access insufficiency will be the first sign – blood is stuck in lungs not getting to circuit

You shouldn’t need to give a fluid bolus – so if doing this, consider LV failure is evolving (dilating LV with inability to pump out)

Offloading the LV – may need to decompress by creating a vent between L and circuit, R heart – there’s potential to use impella to suck blood out directly

Retrieval Final Checks Before Departure

  • Adequate oxygen and power supply
  • Confirm haemodynamic goals with ECMO specialist
  • All taps have stopcocks on
  • Access line dark, return line bright
  • Circuit flows stable
  • Lines secured, away from snag hazards
  • Patient sedated and paralysed

If you work for Sydney HEMS, take a look at the new ECMO class available through the virtual learning environment.

A/Prof Paul Forrest: VA ECMO in Sepsis

A/Prof Forrest talked a little bit about VA ECMO in sepsis.

The key to the septic shock definition is MAP 60mmHg (or inotropes required to keep it here).

Most adults dying from sepsis do so in a high output state (increased cardiac output with decreased systemic vascular resistance): this paper from 1984 looked at 20 patients with severe septic shock – 50% had moderate to severe decrease in left ventricular function. Notably they found the left ventricular ejection fraction had returned to normal within ten days in those who survived.

This leads us to consider whether low ejection fraction might be a good thing in patients with septic shock – this review by Vieillard-Baron et al from 2001 seems to support the hypothesis.

It’s possible, then, that the relationship between survival and non-survival depends on systemic vascular resistance in the context of vasoplegia – this allows for left ventricular ejection fraction to be maintained against lower resistance

There’s some evidence we might consider in paediatric patients:

MacLaren et al described their experiences with VA ECMO for septic shock in children.

They looked at 45 patients, of whom 21 survival (47%). In terms of central vs peripheral VA ECMO, survival proportions were 73% vs 44% and no survivors severely disabled. The authors felt that their data suggested that central configuration might provide a survival advantage.

The same team published a further paper in 2011: in this paper they studied 23 patients, 17  of whom survived to discharge (74%): they noted that a high lactate predicted worse survival.

As a result of this work, the American College of Critical Care Medicine’s paediatric sepsis guidelines published in 2017 include ECMO if the child has persistent catecholamine refractory shock.

For adults the data is lacking; literature only describes around 200 adults on VA ECMO when case series are combined and there are considerable different baseline characteristics between patient groups.

Cheng et al studied adult patients requiring ECMO for the management of sepsis in their paper on predictors of survival: they found that gram +ve sepsis does better than gram –ve or fungal.

There is also the possibility (in adult patients) of using V-AV ECMO: this is when a second return line is sited in the internal jugular (or similar) with the aim of providing oxygenated blood to the right heart. The femoral artery is part of a higher pressure circuit than the internal jugular line and it can be tricky to regulate flow between the two lines. As yet there is little data on this: this case series by Yeo published in Critical Care in 2016 reports a 50% survival with this technique for adults with severe ARDS and septic shock.

Indications for VA ECMO in refractory septic shock

For paediatric patients – central VA ECMO seems the best option

For adult patients:

  • In the presence of severe ARDS: V-AV ECMO
  • In the absence of severe ARDS: VA ECMO

VA ECMO in septic shock

In summary, VA ECMO in septic shock seems to be good for:

  • Kids with or without CA
  • Adults with low cardiac output/high systemic vascular resistance state

but more evidence is needed.

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

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Combined Education and Clinical Governance Day Christmas Special -13th December

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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

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Clinical Governance Day – 29th November

The Physician Response Unit – An overview. Bill Leaning, Critical Care Paramedic, London Ambulance Service and London HEMS

We were privileged to hear from Bill Leaning via Skype, who spoke about the Physician Response Unit in London. Established nearly 20 years ago, it represents a productive collaboration between London’s Air Ambulance, Bart’s NHS trust and the London Ambulance Service. It’s vision of bringing the emergency department to patient’s homes is achieved by having senior emergency department doctors and paramedics travel by car to patients in the community. Community initiated treatment helps prevent unnecessary ED presentations and ambulance transfers. As well as the obvious benefit to the patient, the collegial relationship between the two clinicians gives each a valuable insight into the others role and skill set. The service has recently been remodeled to allow it to deliver community emergency care 24 hours a day, 7 days a week.

Leaning

The Anatomy of a Difficult Case. Dr James Moran – Retrieval Registrar, Sydney HEMS

Jamie discussed the value of reflecting on difficult cases and bravely used one of his own recent cases to illustrate the point. Indeed, the Australian Medical Council’s Code of Conduct recommends that “Maintaining and developing knowledge, skills and professional behavior……. requires self-reflection”. Although there is little guidance available on how to actually do this, there is no doubt that the ability to critically reflect on one’s performance and ask hard questions of yourself will inform your future practice for the better. Suggestions include keeping a reflective logbook, and formal peer review.

An update from the Institute of Trauma and Injury Management. Michael Dinh – NSW ITIM

The NSW Institute of Trauma and Injury Management (ITIM), an institute within the Agency for Clinical Innovation (ACI), is the body responsible for overseeing, coordinating and supporting the NSW trauma system. Clincial director, Dr Michael Dinh, spoke about the role of ITIM in influencing access, care, outcomes, education, research and quality of trauma care in the NSW region.

Dinh

Don’t forget there will be no Clinical Governance Day on the 27th December. The next meeting on the 13th December will be a combined Education Day and Clincial Governance Day. See you then.

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Clinical Governance Day – 29th November

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ECMO Education Day – Wed 15th November 2017

Not long to go until our ECMO Education Day this week…

If you intend to attend, you must REGISTER HERE

ECMO Flyer

 

We appreciate the kind sponsorship of this event from the following companies:

  • Stryker Medical ; Supply of the demonstration LUCAS 3 mechanical CPR equipment and kind provision of catering for the event.
  • Getinge Australia ; Supply of the demonstration Cardiohelp ECMO Machine.
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Clinical Governance Day – 1st November

Graphs and Gaffs

Matt Miller continued his ambitious mission to teach us all research methods in manageable 20 minute blocks. This month focussed on the use of graphs, using some amusing, published, graphs to illustrate how data can be misinterpreted if graphs are not presented correctly.

Key learnings were:

  • Take care with your Y axis.  It should include zero and the axis units need to be appropriate for the data being presented
  • If using two graphs for comparison, the scale should be the same
  • Make sure your graphs are not so busy that the message gets lost
  • When reading a paper, make sure you understand how the data has been presented before drawing any conclusions
  • Ensure you actually need a graph to illustrate a result. Sometimes text will do.

pie chart

Give PEEP a chance (or not)

Das Ragavan presented an update on the use of PEEP in patients with ARDS by reviewing the recently published randomised clinical trial from the ART group. In summary, in patients with moderate-severe ARDS, a ventilation strategy with lung recruitment and titrated PEEP compared with low PEEP increased 28 day all-cause mortality. Routine use of lung recruitment and PEEP titration in this patient group was not recommended.

A link to the paper can be found here:

https://jamanetwork.com/journals/jama/article-abstract/2654894

Blood Audit

A reminder from Karel Habig that the state wide “Code Crimson” pathway is now live.

Cover-image-Trauma-Code-Crimson-Pathway

This pathway aims to standardise the:

  • pre-hospital identification of a trauma ‘Code Crimson’
  • activation of a trauma ‘Code Crimson’ pathway by pre-hospital medical retrieval teams and the subsequent notification to a receiving trauma centre
  • procedures instituted by trauma centres following activation of a trauma ‘Code Crimson’ pathway.

The most relevant sections for our service list the criteria for activation and outline the activation procedure.

Cirtieria for code crimson

Capture

The entire pathway document can be found here.

https://www.aci.health.nsw.gov.au/__data/assets/pdf_file/0003/382917/Trauma-Code-Crimson-Pathway-Final-20170919.pdf

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