An Impedance Threshold Device in Out-of-Hospital Cardiac Arrest

To the Editor: Aufderheide et al. (Sept. 1 issue) 1 report on the logistically challenging, cluster-randomized Resuscitation Outcomes Consortium Prehospital Resuscitation Impedance Valve and Early Versus Delayed Analysis (ROC PRIMED; ClinicalTrials.gov number, NCT00394706) trial; they compared the use of an active impedance threshold device (ITD) with that of a sham device in patients with out-of-hospital cardiac arrest. The study was conducted concurrently with a companion study of early rhythm versus later rhythm analysis. Patients were typically enrolled in both studies, which potentially delayed placement of the ITD. Use of the ITD did not improve survival with favorable neurologic function. The interpretation . . .