In this episode Zack and Joe discuss the CHEER Trial (mechanical CPR, Hypothermia, ECMO, and Early Revascularization) and follow up with Dr. Stephen Bernard with a few more questions about ECMO at the Alfred. Just days after we published our initial interview With Dr. Stephen Bernard from the Alfred Hospital in Melbourne, Australia, the CHEER Trial was published.
Background: Recently, we reviewed two big papers in the ECPR (Extracorporeal Cardiopulmonary Resuscitation) World: 1.) The Chen Trial (Lancet 2008): a large prospective observational study of in-house arreest (IHCA), out of Taiwan, that showed 32.6% (ECPR) benefit vs. 17% (non-ECPR); and 2.) The Save-J Trial (Resuscitation 2014): a large prospective observational study of Out-of-Hospital cardiac arrest (OHCA) that showed a 11.2% (ECPR) benefit vs. 2.6% (non-ECPR). Indeed these numbers are impressive! We all know that we need a randomized, controlled trial (RCT) but until then the guys at the Alfred Hospital in Melbourne, Australia decided to up the ante and published the initial findings of this pilot study. That study was called CHEER. This amounts to a hyper-aggressive, bundled protocol that begins on the street (EMS) and ends in the cath lab, whereafter world-class critical care has resulted in some remarkable initial numbers.
This is a single-center, prospective, pilot study that was done over 32 months. The primary outcome measure was short and long-term outcomes at CPC 1 or 2 (excellent neurologic outcome). The guys down-under generated inclusion criteria to capture the most salvageable patients who suffered out-of-hospital cardiac arrest (OHCA), combined those with in-hospital cardiac arrest (IHCA) patients and applied the CHEER algorithm:
- CPR (using the Zoll Autopulse)
- Hypothermia (initiated intra-arrest with iced saline)
- ECMO (cannulation in the ED by intensivists)
- Early Revascularization (aka a trip to the cath lab)
And all this was begun in the prehospital setting. Since the EMS system in their neighborhood is a single-provider system, they were able to get support from Zoll Pharmaceuticals to supply all of their rigs with their mechanical chest compression device – the Zoll Autopulse. Patients who met inclusion criteria were met by EMS, put on the Autopulse, and transported to the Alfred. EMS also began intra-arrest cooling by rapid infusion of iced saline at 30cc/kg. On arrival to their Emergency Department, intensivists met the patient and began the cannulation process. Once on ECMO the patients were immediately brought to the cath lab for revascularization. IHCA patients received the identical protocol, obviously minus the limo ride to the hospital.
In 2014 this amounts to a super-aggressive bundle therapy that just makes us salivate over here in the US. Initiating intra-arrest cooling and mechanical chest compressions in the pre-hospital setting is formidable goal for us.
Their results: 26 patients were entered into the protocol (11 with OHCA, 15 with IHCA). The median age was 52 years. ECMO was established in 24 (2 patients in the OHCA arm were pushed through the protocol but didn’t actually go on pump; one was cannulated but achieved ROSC prior to going to cath lab and therefore was not put on bypass, and the other patient had a failed cannulation attempt but was taken to the cath lab anyway (presumably on Autopulse) and survived. Both OHCA patients and IHCA arrest patients were grouped together in their outcome data. ROSC (return of spontaneous circulation) was achieved in 25 (96%) patients. 13/24 (54%) were able to be weaned from ECMO support and survival to hospital discharge with full neurological recovery (CPC score 1) occurred in 14/26 (54%). These are remarkable initial results that higher than what we’ve seen in larger studies.
- Why such good outcomes? The patient-oriented outcomes in this pilot study are remarkable. Why are their numbers so much higher than much larger studies we’ve seen in the past? Was it the small sample size? Was it because they grouped the OHCA and IHCA arrest patients into their outcome measures (with IHCA outcomes historically known to be much better)? Was it the bundle?
- Which therapy really made the difference? Was this the result of aggressive pre-hospital cooling? Was it the result of a “load-and-go” EMS policy with proper use of the mechanical chest compression device? Was it rapid deployment of ECPR? Likely, its all of these. Like much in the resuscitation world, its likely the bundle (the CHEER) followed by excellent critical care at their ECMO facility. But we can’t say for sure.
- Mechanical chest compression devices (ie the Zoll Autopulse or the LUCAS2 by Physio-Control). 3 studies so far have basically shown no benefit of these devices over good quality human CPR. But most resuscitationists who have used these devices believe in their utility. I believe in their utility. Many of the reasons are less tangible than the patient-oriented outcomes measured in those papers. One of those intangibles is highlighted in this study: patients can be safely and rapidly transported to the ED with excellent ongoing chest compressions, and rescue personal can be safely strapped into their harnesses during transport.
Study after study has shown that the single biggest key to the success of ECPR is the time to initiation of bypass. So in this trial, the rapid transport with Autopulse and rapid activation of the ECMO team optimized this interval. But we believe the success of this study would not have been possible without ECMO as the final bridge that could make all this happen. To highlight this concept, on October 14, 2012 Austrian skydiver Felix Baumgartner jumped from the Red Bull Stratos capsule 24 miles above New Mexico, USA and broke 3 World Records: a.) Exit Altitude (24.2145 miles) b.) Maximum Vertical Speed (843.6 mph) and c.) Vertical Distance of Freefall (119,431 ft). And he broke the sound barrier.
Advancements in technology, human transport, a willingness to push the envelope, and huge set of balls, made that happen. But that couldn’t have been done without a relatively simple device that has been around for decades that allowed Baumgartner to land on his feet: the parachute – a device that “bridges” the skydiver from potential free fall-death to soft landing with proper deployment. ECMO can be thought of as one such device.
Update 10/25/2014 Hot off the press: Google Senior Vice-President Alan Eustace one-upped Baumgartner on October 24th when he jumped 135,890 ft from a helium balloon to become the World-record holder for highest parachute jump. Additionally, Eustace used no corporate funding and did not use a capsule, opting instead to be carried into the stratosphere in a space suit alone. Here are some photos of that:
- Check out Part 1 of our interview with Dr. Bernard
- Check out INTENSIVE, The Alfred’s educational website and blog
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