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Five Questions With: Louis Gonzales on Mechanical CPR Studies

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When Jolife AB, the original parent company of LUCAS, brought the device to the U.S., a 2009 feasibility study was conducted with the help of a U.S. consultant. Focusing on how well it functioned and fit patients, the study landed in the city of Austin, Texas. Twelve of the 42 City of Austin Fire Department stations with the highest number of cardiac arrest cases (60 to 75 per month) participated in this feasibility study—it wasn’t a clinical trial—and kept the devices once it was completed.

Three years following the feasibility study, Louis Gonzales, MPH, CPPS, CPHQ, LP and Clinical Quality & Patient Safety Specialist at Austin/Travis County Office of the Medical Director, first observed a flattening of the EMS System’s cardiac arrest survival rate data. A 2014 statistical analysis of the past four years of cardiac arrest data identified an association between the presumed use of a mechanical CPR device and overall survival. Though the research team could not completely explain this negative association, the mechanical CPR device remained in use for “manpower” reasons. A quality improvement effort including scripted mechanical CPR initiation was implemented to address potentially lengthy “hands-off” time.

A December 2016 study by Buckler and colleagues prompted the Austin/Travis County EMS System’s Office of the Medical Director to further evaluate the impact of mechanical CPR on survival to discharge. The team couldn’t believe the quality of outcomes was decreasing when mechanical CPR was implemented based on the initial crude data analysis. Although the 2017 study received some criticism after the online publication in the American Journal of Emergency Medicine, Gonzales believes the message is crucial to revealing why we must continuously challenge and evaluate current practices to ensure the safety of both patients and providers.

EMS World: What did the recent study findings say about patient outcomes associated with mechanical CPR?

Louis Gonzales: We are CARES (Cardiac Arrest Registry to Enhance Survival) participants, so when CARES added the data element for mechanical CPR use, we adopted that immediately. Around 2013, we looked at rough data which made us concerned that there may be a difference in outcomes when the LUCAS is used and not used. Our numbers were really small at the time, so it was more like a hypothesis. We were initially hypothesizing that we would have improved outcomes [in terms of survival to discharge] because that's what we were hearing from the field. We kept tracking the data and identified a year or two later that the trend was actually going in the other direction. There appeared to be a lower likelihood of survival when mechanical CPR was used. It did not make sense to us. It was so well-received by the fire department.

We worked with our System Medical Director, Dr. Paul Hinchey, on organizing re-training for the fire department. In that 2015 quality improvement effort, Dr. Hinchey created a training program with an emphasis on high-quality CPR, whether it's manual or mechanical. About a year later in 2016, we were able to do another crude data analysis. Again, it looked like we had worse outcomes with the LUCAS. The theory is that it’s caused by the interruption in compressions by placing the device on, even though we practiced it in the classroom. It's just different in the real world.

What was the conclusion of the study?

We hired a statistician to crunch the numbers and what we found was a person has roughly one third less of a chance of survival if they receive mechanical CPR instead of manual CPR. Though we recognized our findings were simply indicating an association and not a direct cause and effect relationship, the findings were very difficult for many to accept.

In 2017, I looked at the crude numbers using end-of-year cardiac arrest reports. I sent the statistician the numbers to re-run the data. I don't know how many different ways we looked at it. Could it be certain airway devices that were complicating the survival rate? Was it the medications we were giving? Were the ones with manual CPR surviving because they got early resuscitation before mechanical CPR could even be put on?

We excluded a number of cases to make these more similar in terms of looking at risk of survival. We excluded early survivors [meaning they got a pulse back quickly] because that could actually favor manual CPR. We need more research, but the study raises questions. Why would mechanical CPR be associated with less optimal outcomes?

How did the Austin Fire Department adjust its practices according to the results of the study?

We were criticized early on with the results when the electronic paper came out because EMS providers thought we were saying that LUCAS causes harm. That’s not what we’re saying. The crux of the paper is that even after this quality improvement effort and changes to the indications for the LUCAS application, the findings remained the same. Before, it was ‘If it’s there, you use it.’ We changed it to ‘Only use it [LUCAS] for transport or if you have limited or exhausted resources.’

Early on we changed the manual CPR protocols. We let the crews do their compressions on a manikin and what we found was the first compressor’s quality of compressions slowly decreased in that second minute. We changed compressors so that the rested person will have good quality for the second minute of the compressions. Dr. Hinchey changed it to where our pit crew has two people who are compressors only. That's how we arrived at our protocol for a 2-minute cycle with one minute done by each compressor. Our focus was on the perfusion aspect. It allows us to minimize interruptions in compressions, so they only get interrupted by the AEDs when they’re analyzing.

Did the department eventually limit its use of the LUCAS because of the protocol changes?

We did seem to decrease use of the LUCAS, but Dr. Mark Escott, our current medical director, felt this was from a patient safety concern. How could we continue to use it as we were using it with the data we had? It wasn't perfect data, but it was our data. Others might have been able to show something different, but our data was based on our firefighters and their performance.

Our LUCAS devices are being phased out now because of the cost. They cost about $12,000 a piece and to keep all of them calibrated cost nearly $100,000 a year for a device that we didn't have the data to show benefit for survival. The only real benefit was provider safety during transport.

After the protocol change, we were finding that the LUCAS was being used no more than a half-dozen times a month. We want the paramedics to have the autonomy to make decisions that make sense. If they're doing it just because it's easier, that's not a good reason. But even when they decide to transport, we want them to give high-performance manual CPR a chance first. We try to work most of our cardiac arrests on scene and either resuscitate them or don’t transport.

What was the take-away message with these findings?

If you have a low probability of benefit, are you putting these providers and the public at risk? You have to explain to your crews that when evidence lacks, we choose treatments based on what seems to make the most sense. Things change as we learn new science, so don't get stuck on new interventions. We often don’t like that concept because we want to find something like the LUCAS—we're looking for a magical device and there are no magical devices. With the LUCAS, it's most likely not the device but the human aspect of being able to put it on the patient. That part competes with our “don't interrupt CPR” objective. So far, what we know works best is high quality CPR and defibrillation if they're in a shockable rhythm.

Louis Gonzales, MPH, CPPS, CPHQ, LP is the Clinical Quality & Patient Safety Specialist at Austin/Travis County Office of the Medical Director. He was trained as a paramedic in the Seattle Medic One Program 27 years ago.


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