The LINC trial

I wouldn’t regard myself as a total nihilist when it comes to cardiac arrest but I’m usually not on the optimistic side. I work in a typical inner city setting where outcomes from OOHCA are on the poor side. I suspect are numbers are polluted by the fact that our local EMS system only occasionally stops CPR on scene. We get a lot of patients transported with (manual) CPR in progress. Most of these patients have not responded to a substantial period of ACLS and are simply dead and typically I stop resus as soon as they arrive.

There are of course some very important exceptions to this, the people who we know have a more favourable outcomes: bystander CPR, short down times, reversible causes, VF/VT, younger age etc… These are the people where the mantra of maximally aggressive care goes into action. Thus there’s a stark contrast in my practice between the patients who appear to me to be obviously dead and don’t need ACLS – they need a death certificate – and the patients for whom ACLS is simply not enough, or at the very least it doesn’t account for the nuances needed in advanced critical care.

The FOAMed sphere is full of advanced resuscitation resources from some of the best resuscitationists in the world. That’s where I’ve learned most of my critical care.

All this is just an introduction to the LINC trial. It’s been out for a while and I’ve linked to some of the other FOAMed reviews out there but I figured I’d throw in my own two cent.

METHODS

  • industry sponsored RCT
  • Sweden, Netherlands and UK
  • excluded those with an inappropriate body size so we don’t know how many this will be applicable to
  • the LUCAS protocol had a slightly different protocol with 3 mins v 2 mins. It has been suggested that was due to rescuer fatigue in the manual group. But either way it shows that the two groups were not treated the same. The mechanical group also got an extra DCC 90 secs after the LUCAS was put on.
  • outcome was survival at 4 hrs which is a bit soft
  • CPC outcome was done from the notes which is open to some biases
  • those with ROSC got hypothermia for all rhythms though I don’t think this was pre hospital
  • they assumed a 25% 4 hr survival which seems a touch high but then they weren’t measuring good neuro survival here as a primary outcomes

RESULTS

  • 2500 pts 30% VF/VT
  • 23% survival for both groups
  • in those that survived there was about a 35% PCI rate.
  • 8% surviving to hospital discharge with good outcome (CPC 1&2)
  • it is interesting to note that you either died or you did well. There weren’t many survivors with bad outcomes. Which is perhaps the most important finding of the whole study. They were virtually all CPC 1. It may be that when a poor outcome was anticipated (say at day 3 post arrest) then aggressive treatment was withdrawn and the patient succumbed.

THOUGHTS

This is a remarkably negative study from a strictly EBM point of view. So any routine (ie for every single cardiac arrest) use is hard to justify given the cost of implementing this device in all EDs and all EMS crews.

Good, coordinated, team CPR is hard to do well and like most things you only get really good at it when you practice. A lot. Like most EDs I’ve worked in we don’t practice, we do our ACLS courses but we don’t practice as a group to deal with all the small logistic factors that turn a straightforward resus into a chicken bomb. We use the LUCAS in certain cases  – the exceptions where I think continuing CPR will allow an intervention or produce a positive outcome – an every time I do I’ve noticed a better atmosphere in the room. As the team leader (as well as the interventionalist – it’s usually just me and my nurses and some very junior docs who can’t even put an IO in) it allows me a bit more cognitive space as I don’t need to keep an eye to monitor the rate and quality of the CPR.

If ECLS becomes a mainstream possibility (which in this country seems unlikely) then mechanical CPR is likely to have even more of a role. The key is of course patient selection. The heart too good to die is fairly rare. For most patients I look after, cardiac arrest is the natural course of age and massive comorbidity.

The logistic factors that give you an advantage (freeing up hands and cognitive space) for those long and infrequent resus cases that makes me glad that we still have one in the resus room.

References:

Hallstrom Al, Rea TD, Sayre MR, Christenson J, Anton AR, Mosesso VN, et al. Manual Chest Compression vs Use of an Automated Chest Compression Device During Resuscitation Following Out-of-Hospital Cardiac Arrest: A Randomized Trial. JAMA. American Medical Association; 2006 Jun 14;295(22):2620–8.

Rubertsson S, Lindgren E, Smekal D, Östlund O, Silfverstolpe J, Lichtveld RA, et al. Mechanical Chest Compressions and Simultaneous Defibrillation vs Conventional Cardiopulmonary Resuscitation in Out-of-Hospital Cardiac Arrest. JAMA. 2013 Nov 17.

FOAMed Reviews:

Rory Spiegel at EMLit of Note

ALIEM

LITFL CCC

ScanCrit

Image Credit Wikimedia Commons

About Andy Neill

EM Reg/Resident based near Dublin. Former anatomy lecturer, theology student and occasional musician @andyneill | + Andy Neill | Contact

Comments

  1. Great little review. I’ve added commentary to our further reading at http://www.wikem.org/wiki/EBQ:LINC_Trial#Further_Reading

  2. Hi Andy, great post.

    It is interesting to see another negative trial on mechanical CPR devices. To my knowledge there has yet to be a compelling study that demonstrates any benefit in their routine use. However this has not seemed to have dimmed the enthusiasm for these devices.

    I appreciate that there is probably a niche for them to be used as a bridge to ED ECMO and PCI in very select patient populations (such as our own feasability study here in Melbourne, CHEER)

    It seems (at this very early stage of the game) that there will be great potential in this approach to achieve some great outcomes. However it is an extraordinarily resource intensive approach. Use of the mechanical devices themselves is actually quiet a logistically challenging process if one wants to do it to ensure absolutely minimum interruptions to CPR (which should be the goal) and will not reduce the number of personnel at the scene. I can only imagine that the hospital side of things also sucks up a huge number of resources as well.

    I wonder what would happen if we were to channel those resources (dollars) into public CPR and Public Access Defibrillation, the two interventions that seem to provide the most bang for the buck currently?

    I’m sure ECMO as a bridge to PCI will gain momentum, and it certainly seems like it has the potential to save lives. I just hope that we don’t lose sight of where we need to be committing scarce healthcare dollars.

    Oh, and also alarmed to hear of crews putting themselves at risk doing CPR on a corpse whilst driving to hospital… Should I come over and sort them out a bit?!

    Cheers,
    Robbie

    • Cheers Robbie. Great point on providing more Defibs and CPR, as you say that’s where the real advantages are. Hard to justify a LUCAS over a defib.

      I don’t want to think how they’re doing CPR in the back of the bus but the transport times are virtually all <5mins so at least it’s brief

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