With promising animal data, ongoing investigation across three continents and variations already hitting the streets in South Florida, the next important innovation in CPR could be right around the corner. It’s called heads-up CPR, and it entails, among other aspects, elevating the patient’s head during resuscitation to allow gravity to help improve blood flow in and out of the brain.
“There’s such a long history of poor survival for adult cardiac arrest despite all the things we’ve done,” says Ken Scheppke, MD, medical director for Palm Beach County Fire Rescue, one of the agencies already putting the idea into practice, “that when something comes along like this—it’s simple, but there’s a good, clear-cut sense that it should help physiologically—I think we should keep trying new ideas to improve care for that segment of the population.”
With human trials yet to come, this implementation—by a half-dozen agencies in Palm Beach County and two in Broward—lays important groundwork by demonstrating safety and feasibility. It’s part of a new medical direction team’s new management formula that has helped steadily increase PBCFR’s all-rhythm ROSC rate from 16% in 2014 to now over 40%, including 48% in May.
Elevation of the head, though, is just one piece of the plan.
The idea started with a conversation about elevators. In South Korea, where many people live in high-rise apartments, it can be hard for emergency crews to conduct CPR while bringing cardiac arrest patients down those small compartments. To solve this some advocates designed a type of wheeled, foldable stretcher-cart. On a trip to that country in late 2013, University of Minnesota cardiologist Keith Lurie, MD, saw a prototype.
“They had a manikin on the stretcher,” Lurie says, “and when they got to the elevator, they were doing CPR, and they put the manikin’s feet up. I said, ‘You’re going to kill people with that! You need to do just the opposite—you need easy-chair CPR.’”
Their curiosity piqued, a group including Lurie, South Korean colleague Sang Do Shin, MD, PhD, and French emergency physician Guillaume Debaty, MD, gathered at UM’s labs soon after to study the question further in a pig model. They quickly confirmed that using a feet-up/head-down position during resuscitation yielded a high intracranial pressure and low cerebral perfusion pressure, while with a head-up/feet-down position, ICP plummeted and CPP increased.
Sedated on a tilt table, the pigs underwent six minutes of untreated ventricular fibrillation, then CPR using Physio Control’s LUCAS device for automated chest compressions and ZOLL’s ResQPOD impedance threshold device (ITD) to enhance hemodynamics. They received the combination supine, at a 30-degree head-up tilt (HUT) and then at a 30-degree head-down tilt (HDT). Other angles were tried on other pigs. Microspheres measured organ blood flow.
Coronary perfusion pressure was 19±2 mmHg at 0º; 30±3 at 30º HUT; and 10±3 at 30º HDT.
Cerebral perfusion pressure was 19±3 at 0º; 35±3 at 30º HUT; and 4±4 at 30º HDT.
Brain blood flow was 0.19±0.04 ml/min(-1)/g(-1) at 0º; 0.27±0.04 at 30º HUT; and 0.14±0.06 at 30º HDT.
As HUT angles increased from 0–50º, ICP fell steadily, cerebral perfusion pressure increased linearly, and coronary perfusion pressure remained constant.
Their conclusion: “During CPR, HDT decreased brain flow whereas HUT significantly lowered ICP and improved cerebral perfusion. Further studies are warranted to explore this new resuscitation concept.”1
Additional experiments used a device to elevate just the pigs’ heads and shoulders and compared that position vs. supine, as well as true active compression/decompression (ACD) CPR (see sidebar) plus ResQPOD flat vs. head-up.
“What we observed with the standard-CPR animals was that there was actually a small increase in the coronary and cerebral perfusion pressures, but after 20 minutes we couldn’t resuscitate any of the pigs in either of the groups,” says Lurie. “By contrast, at the end of 20 minutes with the head and shoulders up, using ACD and ITD, we saw much higher cerebral and coronary perfusion pressures.”
Some of that data’s been presented, and more will be. “Now,” adds Lurie, “we’re in the process of determining whether this can be applied to humans with something other than a Pelican case.”
Putting It Into Practice
The Pelican case is the novel method of raising the head devised by the providers of Palm Beach County Fire Rescue. PBCFR also uses the LUCAS, ResQPOD and a scoop stretcher in bringing head-up CPR to the field.
Its crews place the patient on the LUCAS and scoop, then place a Pelican case on the stretcher before the patient. Then they raise the stretcher head and run the shoulder and waist straps through the scoop handles.
“When we rolled out our educational focus on resuscitation earlier this year, we challenged our paramedics to come up with a way to handle this new concept of heads-up CPR,” says Scheppke. “We’d been impressed with the preliminary laboratory data presented at this February’s Gathering of Eagles conference by [conference director and renowned emergency physician] Dr. Paul Pepe, who is one of Dr. Lurie’s fellow investigators in the lab. It was perfect timing—we’d just gotten approval from the University of Texas Southwestern Medical School to have Paul serve as our research and educational consultant. He met with our PBCFR team members and challenged us to find a feasible way of doing this, so we were primed, and this was one of the things our paramedics came back with.
“With the shape of the scoop and the shape of the LUCAS board, it sort of locks itself in place and keeps the LUCAS from migrating. It also makes the patient much more mobile. Then they discovered they could very simply raise the head by placing a Pelican box under the head of the scoop stretcher. So then we have continuous chest compressions going, with the angle we want for head-up CPR.”
Other Palm Beach County fire-rescue agencies trying heads-up CPR include those of West Palm Beach, the Town of Palm Beach, Palm Beach Gardens, Boynton Beach and Greenacres. In the next county south, Broward, Davie Fire Rescue and the Coral Springs Fire Department have joined them. The medical director for those services, Peter Antevy, MD, is also the associate medical director for PBCFR and worked closely with Scheppke and Pepe on the idea.
Some of those agencies use ZOLL’s AutoPulse instead of the LUCAS, and there are other slight differences in implementation. In Davie, for instance, the AutoPulse and patient are placed on a tarp, then moved to the stretcher, and the stretcher is angled to 30 degrees. No longboard is required, and it makes things logistically simpler.
“There are going to be differences in how this is rolled out; we have to understand that,” says Antevy. “We’re still learning about this concept and thinking through the process, but it’ll be pretty interesting to see where it all settles. We now have almost all of Palm Beach County and small pockets of Broward County doing it, which will give us data back, like a small field trial. If we can get some good data out even before a randomized trial, that may speed up the whole process.”
“What these guys are doing in South Florida is developing excellent groundwork for a controlled clinical trial,” says Pepe, MD, MPH, a tenured professor of emergency medicine at UT Southwestern and a veteran of two dozen clinical trials in the out-of-hospital setting. “And with the dramatic concomitant rise in resuscitation rates at PBCFR, this groundbreaking initiative will also make ensuing grant applications to conduct the clinical trial all the more attractive.”
Good Blood to the Brain
Why does heads-up CPR seem to work? Basically, standard supine chest compressions increase arterial and venous pressures simultaneously, reducing the possibility of a cerebral perfusion gradient.
When you compress the chest in conventional CPR, it sends an aortic pressure wave to the brain that provides blood pressure and, theoretically, blood flow. But you’re also creating a backward-moving pressure wave on the venous side. This works against venous return and increases ICP.
“Think about a turkey baster,” explains Pepe. “You suck something in, then you squirt it out. Well, in this situation, it’s a closed system, and as you squeeze the chest, you’re simultaneously squirting things out on both the venous and arterial sides into a fixed space. So you’re likely pounding the brain in a way that creates increased intracranial pressure from both sides.”
Elevating the head uses gravity to help offset that venous pressure component and helps to drain the brain, and the automated compressions and ITD help enhance flow further.
“By simply elevating the head, we cause the venous drainage to be accelerated because of gravity,” says Lurie. “And with the ITD and ACD combination, blood is actually pulled out of the brain during the decompression phase. So the ICP falls, and then during the subsequent compression phase, there’s a lot less resistance to more forward flow. So you increase cardiac preload, and you deliver more good blood to the brain without the resistance.”
“To help our folks conceptualize it, I told them to remember when they were kids and would hang upside down on monkey bars,” says Scheppke. “When you do that, you feel all the blood rush to your head. But you can only fit so much in the head, and if your head’s filled with venous blood, how are you going to fit the arterial blood in there? So it made sense to them that if you drain that venous blood out, now there’s room for the arterial blood. It’s a quick way to visualize how this drops the ICP and gives you better arterial flow.”
This idea is still new, and work toward fleshing it out continues on several fronts. In Minnesota they’re examining survival benefits in an animal model and working toward study on human cadavers, as well as developing a device to facilitate raising the patient’s head and shoulders. Shin in South Korea and Debaty in France continue their research, and collaborations with Pepe have begun as well. A body of data builds in South Florida, paving the way for human clinical trials.
A possible concern is that tilting the entire body upward for too long could lead to blood pooling in the abdomen and legs, decreasing the volume available to circulate. That’s something to watch for as study continues. Everything else, though, appears pretty positive so far.
“Probably the most important physiologic reason this may work is that pressures are transferred almost instantaneously from the right heart to the brain,” says Lurie. “If the pressure in the right heart is high, then the ICP is high. And if pressure in the right heart—the right atrium in particular—is low, then ICP is low.
“When you do CPR, right heart pressures go up and down with each compression/decompression phase. But when you elevate the head, the right heart pressures are overall much lower. If you elevate the feet, the right heart pressures are overall much higher. So that relationship between the heart and the brain on the venous side, we believe, is fundamental to improving neurologic outcomes.
“One of the reasons I think ACD-ITD works is because we now know we lower intracranial pressures because we’re lowering right-sided pressures. We’ve for years thought about getting higher arterial pressures and better arterial blood flow to the brain; we’ve forgotten about this relationship between the right side of the heart and venous pressure. That concept is fundamental to all methods of CPR, and we make it strikingly better with this head-up concept.”
Active compression/decompression CPR (ACD CPR) is more than just automated compressions. It actively re-expands the chest during the decompression phase by use of ZOLL’s ResQPUMP. With this device, a suction cup on the chest lifts the thorax as the rescuer pulls up holding the handle. This extra lifting force enhances the intrathoracic vacuum during chest wall recoil, resulting in more blood being returned to the heart. This enhanced preload then leads to increased cardiac output on the subsequent chest compression. For more: www.advancedcirculatory.com/resqcpr-system/.
A new combination of resuscitation tools originally approved by the FDA in March is now coming to market after its commercial sale was greenlighted in June.
The ResQCPR system from ZOLL combines the ResQPUMP ACD CPR device and the ResQPOD ITD 16. It’s designed to deliver intrathoracic pressure regulation (IPR) therapy during cardiac arrest resuscitation. IPR therapy regulates pressure in the chest to enhance perfusion when blood flow is low.
In a clinical trial, use of the ResQCPR system increased one-year survival rates by 49% over patients who received conventional CPR. It is the only CPR device, the company notes, with an approved indication to increase the likelihood of survival.
1. Debaty G, Shin SD, Metzger A, Kim T, Ryu HH, Rees J, McKnite S, Matsuura T, Lick M, Yannopoulos D, Lurie K. Tilting for perfusion: head-up position during cardiopulmonary resuscitation improves brain flow in a porcine model of cardiac arrest. Resuscitation, 2015 Feb; 87: 38–43.
2. Debaty G, Shin SD, Metzger A, Ryu HH, Kim T, Rees J, McKnite S, Matsuura T, Lick M, Yannopoulos D, Lurie KG. Abstract 88: Gravity-Assisted Head-up Cardiopulmonary Resuscitation Improves Cerebral Blood Flow and Perfusion Pressures in a Porcine Model of Cardiac Arrest. Resuscitation Science Symposium, Session VII: Best Original Resuscitation Science Poster Session.