Monday, November 17, 2014

Inspiratory Threshold Device Works if CPR is Adequate: New Evidence from ROC-PRIMED Trial

Re-Analysis of Data from the ROC-PRIMED Trial, presented at the AHA meeting in Chicago, shows that if CPR is done at the correct rate and depth, that the Inspiratory Threshold Device (ITD) improves survival from 4.1% to 7.2%. 

The ITD inhibits entry of air down the endotracheal tube for a fraction of a second, so that increased NEGATIVE pressure is created in the chest during recoil from chest compressions.  This negative pressure increases venous return, cardiac output, and coronary blood flow.

There are numerous laboratory experiments that prove this, and many studies in patients with hypotension from various causes (here is one study I conducted myself on spontaneously breathing hypotensive patients)

And don't forget the Landmark ResQTrial, in which the use of BOTH compression-decompression CPR and ITD increased survival by 50%.

More detail here:

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

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

MINNEAPOLIS/ST. PAUL (November 17, 2014) – 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 being 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 some patients were administered the working ITD and others were treated with a device that looked identical to the ITD but did not perform the intended function. Researchers 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.”

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. The new analysis also showed that use of an active ITD, combined with high quality CPR, 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 professor Keith G Lurie MD and is used widely by hospitals and EMS 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.


  1. How do I trial it in my ER? Do you use it?

  2. Michael,
    We use it on every patient. Our EMS system uses it on every patient. We have the hightest resuscitation rate in the country at Hennepin EMS.
    Steve Smith


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