If you make a study on interventions on dead people, you don’t expect much. Well, the Alfred in Melbourne did such a study – and got a resurrection rate of over 50%! Their intervention group was people in refractory cardiac arrest – which basically means you’re dead. The majority of patients in the CHEER trial had been in cardiac arrest for well over 40 mins. That’s when most of us start thinking about throwing in the towel and call the time. But not in the Alfred. Not on Steve Bernard’s watch.
Cardiac arrest and ECMO
ScanCrit is a big believer in ECMO in general, and there’s more and more evidence mounting that ECMO is doing good for cardiac arrest patients. We already wrote on this back in 2011 when the first big Asian studies came out on in-hopsital cardiac arrest.
Recently, the Japanese SAVE-J prospective, observational multi-centre study came out on OHCA and showed a greatly increased survival when prolonged cardiac arrest patients were put on VA-ECMO. And they backed it with impressive numbers: 260 OHCA patients on VA-ECMO between 2008-2012 were included! And 6 month survival with good neurological outcome went from 2,5% in the control group to over 11% in the ECMO group – a quadrupled rate of survival!
So ECMO is certainly a key intervention in this patient group. But the Alfred hospital wanted to see what happened if you put all known aggressive interventions into one bundle and went all-in on these patients.
The CHEER study
The Alfred did this as a prospective pilot study looking at aggressive interventions bundle in refractory CA, looking for survival with Cerebral Performance Categories, CPC, 1-2 at discharge.
They included both in-hospital cardiac arrests and out-of-hospital cardiac arrests, 15 IHCA and 11 OHCA. 26 patients in all.
Of all these rather dead patients, they took the ones with the biggest theoretical chance of making it. The IHCA at the doctor’s discretion, and for OHCA they included patients between 18-65 (in the actual study this turned out to be 38-60) with initiated CPR within 10 mins, an initial rhythm of VF and arrest of a presumed cardiac origin. They offered these IHCA & OHCA patients a full-on resuscitation bundle (or is it a resurrection bundle?) of aggressive interventions:
- Mechanical CPR with Autopulse
- Therapeutic hypothermia
- Early revascularisation
And in this study, the bundle was a great success. The bundle also included doing the basics right, as outlined in the inclusion criterias: Witnessed cardiac arrest with early initiation of good CPR, and picking the right patients – the ones with a potential for survival and intact brains. So, of course, the inclusion criteria made for a kind of survival bias – but a realistic bias. In real life, this is the group you would offer this bundle.
Focus and interventions
Another critisism would be the rather small number of patients included: 26. While this number was enough to power the study, it’s a quite small group, so the confidence interval of the survival rate is likely to be quite big. Still, an average survival rate of 54% in a group of prolonged cardiac arrest is such an out of the ball park home run that quarreling over the exact figure makes no sense.
It can also be hard to make out exactly what interventions made the biggest difference – but like our sepsis trials have shown, it’s more about having aggressive focus on the issue and doing your basic things right, rather than one or two miracle interventions. For cardiac arrest survival, it is the whole chain of survival that makes the difference.
In cardiac arrest we’re focusing on CPR, but even if this effort is done to increase the chance of restarting the heart, it is really for trying to preserve the brain. Cardio-cerebral-resuscitation. Pure survival numbers doesn’t mean much if they’re all vegetables. In the CHEER study, as in most ECMO studies, they went for good neurological outcome. Meaning CPC 1-2 or similar scoring systems.
In the CHEER trial ALL survivours had a CPC of 1-2! Meaning ALL survivors had good neurological outcome! This is very impressive. Earlier trials have increased CPC 1-2 survivors, but also increased CPC 3-4 survivors, which has been a slight critisism of ECMO CPR – you’re also saving bodies with dead brains. Although I think this is insignificant compared to the large increase in CPC 1-2 in these earlier studies, it’s uplifting to see that results of mostly CPC 1-2 can be achieved. It remains to be seen if these impressive numbers can be replicated – again and again.
We’ve written on mechanical CPR before. How it doesn’t really give better compressions or better outcomes per se, but it facilitates interventions like transportation. Human CPR during transport is probably more for show than providing actual brain perfusion. With mechanical CPR like Autopulse or LUCAS, you can keep good CPR going during transport, and hopefully keep those neurons alive. And for this, mechanical CPR is essential to the chain used in the CHEER study.
The shiny ECMO machine
Talking about the importance of the whole resuscitation chain, I still don’t believe we could have gotten these numbers without the advances in ECMO treatment. That’s where the show stopped earlier: We could do all the basics right. You could have a previously healthy young man with witnessed cardiac arrest and early initiation of good CPR – but if you couldn’t get the heart restarted, you’d soon have to call it. Without ROSC, it was game over. With ECMO, we don’t need ROSC. With ECMO we get ROC. Return Of Circulation.
The whole package
But in addition to the ECMO wonder machine, the focus on aggressively treating this patient group made a big difference, too. The bundle includes many interventions, including the dedication and action from the resus team. So even if the CHEER trial isn’t the big shiny RCT on ECMO many are dreaming about, it does open new vistas just by showing us that a 54% survival rate with good neurological outcome is possible – even in a setting of prolonged cardiac arrest – if everything is done right. Now, that’s something to strive for!
The SAVE-J study:
Extracorporeal cardiopulmonary resuscitation versus conventional cardiopulmonary resuscitation in adults with out-of-hospital cardiac arrest: a prospective observational study, Resuscitation, 2014.