New University of Minnesota analysis shows strong partnership between CPR and a common assist device may result in better outcomes for patients

Thursday, November 20, 2014

Research was presented at the annual meeting for the American Heart Association in Chicago

New analysis shows the use of an impedance threshold device (ITD) in partnership with quality CPR may lead to better outcomes for patients experiencing cardiac events. The analysis was presented at the American Heart Association (AHA) Scientific Sessions in Chicago on November 15, 2014. 

The analysis is a second look from the Resuscitation Outcomes Consortium (ROC) PRIMED Trial, which was published in the New England Journal of Medicine in 2011. This new analysis was led by Demetris Yannopoulos, M.D., research director for interventional cardiology at the University of Minnesota Medical School and the medical director of the Minnesota Resuscitation Consortium. He is also the Robert K. Eddy Endowed Chair for Cardiovascular Resuscitation at the University of Minnesota.

The initial study sought to determine if an ITD, designed to cover the mouth during CPR and increase circulation, can help provide better CPR practice and, consequently, better outcomes for patients experiencing respiratory failure. Researchers employed a blinded model in which the working ITD was administered to some patients and others were treated with a device that looked identical to the ITD but did not perform the intended function. Researchers in the 2011 study reported no difference in outcomes based on the active or sham device. 

“The ROC PRIMED Trial was a landmark study in helping to better understand CPR and the ITD,” said Yannopoulos. “Still, the PRIMED study did not account for the quality of the CPR being performed in partnership with the ITD. We suspected the quality of CPR may make a difference when employing the ITD to help revive a patient.” 

This led the team to revisit the findings. Analysis of the ROC PRIMED data by Yannopoulos and his team shows there is indeed an interaction between CPR quality, the ITD and the primary endpoint of survival to hospital discharge with good neurological function, in contradiction with the results of the initial trial. According to the new analysis, the pairing increased survival to hospital discharge for cardiac arrest patients by a relative 75%. High quality CPR was defined as a compression rate of 80-120 compressions per minute, with a depth of 4-6 centimeters and a compression fraction of >50%, all consistent with AHA guidelines at the time of the study. 

“Our analysis showed when high quality CPR was performed, neurologically-intact survival in the active ITD group was actually 75% higher than when the sham device was used,” said Yannopoulos.

About the ITD

The impedance threshold device (ITD) was conceived at the University of Minnesota by Keith G. Lurie, M.D., and is used widely by hospitals and emergency medical service systems to improve blood pressure and perfusion during CPR. An ITD regulates pressure in the chest to reduce intrathoracic and intracranial pressure and maximize the blood drawn into and pushed out of the heart with each chest compression. These new data further validate that Intrathoracic Pressure Regulation (IPR) Therapy provided by the ITD improves hemodynamics and survival when used with high quality CPR.