It’s increasingly clear that improved outcomes after an out-of-hospital cardiac arrest depend on having a host of protocols in place, rather than relying on one therapy or benchmark. Here’s a look at automated CPR devices in the treatment of sudden cardiac arrest.
Comparative data between manual chest compression and automated CPR are conflicting. The CIRC Trial hopes to change that. Sponsored by Zoll Medical, makers of the AutoPulse, the trial randomizes 5,000 patients who suffer out-of-hospital cardiac arrest to manual or automated CPR. It involves two European and three U.S. sites and will be completed by 2012. The first phase of the study involves field training for the automated device to ensure consistency across sites. Primary outcome is survival to hospital discharge.
“If it’s a positive trial, it will have a major impact in the prehospital—and hospital—settings,” says CIRC investigator Hans E. Luijten, MD, a cardiologist at the Heart-Lung Center of Nijmegen Medical Center, Netherlands.
Luijten is convinced of the value of automated CPR. He has learned that a large proportion of patients who do not have return of spontaneous circulation (ROSC) in the prehospital setting have a fresh MI or pulmonary embolism. The literature shows that treating arrest patients who do regain circulation improves chances of survival. “We have taken it a step further,” Luijten says. “Even though these patients do not have return of their circulation, we take them to the cath lab with the AutoPulse running.”
In a study presented at the 2009 EuroPCR Congress, Luijten reported that four of 16 patients without ROSC who received mechanical CPR before and/or during PCI survived (25 percent) and all four survivors had good neurological outcomes after a year of follow-up. “The survival rate for patients without ROSC and undergoing manual CPR is about 10 percent, and less than 10 percent of those will have intact neurological function,” Luijten says. “Our study is encouraging and suggests the strategy is worthwhile.” Factors in the study predictive of non-survival include a pH less than 7.1 and/or a first lactate level greater than 8.
Keith G. Lurie, MD, a staff cardiologist at St. Cloud Hospital in Minneapolis and a professor of internal and emergency medicine at the University of Minnesota, in 2002 published the first paper detailing a natural mechanism within the body that increases circulation to the heart and brain. By creating a vacuum in the thorax during chest recoil, more blood is pumped to the heart, which results in more blood subsequently being pumped to the brain. Intracranial pressure also is simultaneously lowered. Out of this discovery came the ResQPod (Advanced Circulatory Systems), an impedance threshold device recommended by the American Heart Association that improves survival for patients experiencing sudden cardiac arrest and receiving CPR.
Today, the ResQPod is widely used in combination with automated CPR. In many counties in Minnesota, for example, the EMS personnel use the impedance threshold device with the Lucas (Physio-Control) mechanical CPR device with all cardiac arrest patients, Lurie says. Other major cities such as Austin, San Francisco and New Orleans have followed suit. “Fundamentally, there is this growing momentum to adopt a new approach for cardiac arrest patients,” he says.
Lurie first used the combination on a 46-year-old woman who had had a second cardiac arrest in the rescue helicopter in 2007. St. Cloud Hospital had just deployed the Lucas device in its emergency department after years of using the impedance device with manual CPR. After 49 minutes of the combination treatment, the woman stabilized, had her LAD opened in the cath lab and was cooled down. When she awoke, her neurological functions were intact.
“In the past, we would never recommend transport to the cath lab of a patient with refractory cardiac arrest. But now we can do so in a very stable manner,” Lurie says.
Luijten agrees with Lurie and concludes that ongoing CPR is not a contra-indication for acute coronary angiography and/or PCI and that automated CPR generates high aortic blood pressure not attainable with manual