PRESS RELEASE
FOR IMMEDIATE RELEASE
November 17, 2014
Data Presented at the AHA Shows Use of an Impedance Threshold Device
with High Quality CPR Increased Survival to Hospital Discharge
from Out of Hospital Cardiac Arrest
[November 17, 2014, Minneapolis, MN] An analysis of data from the Resuscitation Outcomes Consortium
(ROC) Trial presented at the American Heart Association (AHA) Scientific Sessions in Chicago showed that
the quality of CPR confounded the results of the trial.1 The ROC PRIMED Trial, published in the New
England Journal of Medicine in 2011, compared conventional manual CPR with an active or sham
impedance threshold device (ITD) and initially reported no difference in outcomes.2 A new analysis of the
data from the trial presented by Dr. Demetris Yannopoulos, MD, of the University of Minnesota, showed
that there was an interaction between CPR quality and the use of the active ITD, confounding the results
of the trial. It also showed that use of an ITD combined with high quality CPR increased survival to
hospital discharge from out of hospital cardiac arrest for patients in the study. Lead author Demetris
Yannopoulos presented the abstract, titled The Effect of CPR Quality: A Potential Confounder of
CPR Clinical Trials, in a podium presentation at the AHA’s Resuscitation Science Symposium on
November 15th. The authors expect full results to be published in 2015.
The authors analyzed data from the ROC Trial to see whether of the quality of CPR had an interaction
with the intervention of an ITD, therefore confounding the results of the study. Their analysis showed
that when high quality CPR was performed, neurologically-intact survival in the active ITD group was
actually 75% higher than when a sham ITD was used. High quality CPR was defined as a compression
rate of 80-120/min, a depth of 4-6 cm, and a compression fraction of >50%, all consistent with AHA
guidelines at the time of the study.
The abstract concluded:
Overall, a total of 848 and 827 patients in the active and sham ITD groups had documented
“quality CPR” performed. Including all presenting rhythms, use of an active ITD increased
survival to hospital discharge with a modified Rankin Scale Score (MRS) ≤3 compared to
sham (61/848 [7.2%] versus 34/827 [4.1%], respectively; p=0.006, OR: 1.8, 95% CI: 1.17,
2.78). There was significant interaction between the active and sham ITD and compression rate,
depth and fraction.
Lead author, Dr. Demetris Yannopoulos, an internationally renowned researcher in the field of
resuscitation and Robert K Eddy Endowed Chair for Cardiovascular Resuscitation at the University of
Minnesota, commented, “The ROC PRIMED Trial was a landmark study that is helping us better
understand CPR and the ITD. Recently published data showed a strong correlation between compression
rates and survival when an active ITD is used. This analysis further explores the relationship between
high quality CPR and the ITD, and our findings are consistent with other published data showing that use
of an ITD with high quality CPR improves survival from out of hospital cardiac arrest.”
The impedance threshold device (ITD) was developed by a University of Minnesota researcher and is
used widely by hospitals and EMS systems to improve perfusion during CPR. An ITD regulates pressure in
the chest to reduce intracranial pressure and maximize the blood drawn into and pushed out of the heart
with each chest compression if the patient is receiving cardiopulmonary resuscitation (CPR). Use of an
ITD in cardiac arrest has been supported by multiple clinical trials and shown to improve survival. The
ROC PRIMED Trial was the first large randomized trial of the device to show neutral results. 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.3-10
The University of Minnesota is a leading research center in the field of resuscitation. Researchers like Dr.
Yannopoulos are finding unique ways to increase neurologically intact survival from cardiac arrest, which
kills thousands of people every day in the United States.
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Yannopoulos et al. The effect of CPR quality: a potential confounder of CPR clinical trials. Circulation XXXXXXXX
Aufderheide et al. A trial of an impedance threshold device in cardiac arrest. NEJM 2011;365:798-806.
Lurie KG, Voelckel WG, Zielinski T, et al. Improving standard cardiopulmonary resuscitation with an inspiratory impedance
threshold valve in a porcine model of cardiac arrest. Anesth Analg 2001;93:649-655.
4. Lurie KG, Mulligan KA, McKnite S, et al. Optimizing standard cardiopulmonary resuscitation with an impedance threshold valve.
Chest 1998;113(4):1084-1090.
5. Pirrallo RG, Aufderheide TP, Provo TA, et al. Effect of an inspiratory impedance threshold device on hemodynamics during
conventional manual cardiopulmonary resuscitation. Resuscitation 2005;66:13-20.
6. Lick CJ, Aufderheide TP, Niskanen RA, et al. Take Heart America: a comprehensive, community-wide, systems-based approach
to the treatment of cardiac arrest. Crit Care Med. 2011;39(1):26-33.
7. Aufderheide TP, Alexander C, Lick C, et al. From laboratory science to six emergency medical service systems: new
understanding of the physiology of cardiopulmonary resuscitation increases survival rates after cardiac arrest. Crit Care Med
2008; 36(11):S397-S404.
8. Aufderheide TP, Yannopoulos D, Lick CJ, et al. Implementing the 2005 American Heart Association guidelines improves
outcomes after out-of-hospital cardiac arrest. Heart Rhythm. 2010;9(10):1357-1364.
9. Thigpen K, Davis SP, Basol R, et al. Implementing the 2005 American Heart Association guidelines, including use of an
impedance threshold device, improves hospital discharge rate after in-hospital cardiac arrest. Respir Care. 2010;55(8):10141019.
10. Hinchey PR, Myers JB, Lewis R, et al, for the Capitol County Research Consortium. Improved out-of-hospital cardiac arrest
survival after the sequential implementation of the 2005 AHA guidelines for compressions, ventilations and induced
hypothermia: the Wake County experience. Ann Emerg Med. 2010;56(4):358-361.
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