Article : Does Use of an Impedance Threshold Device...

Does Use of an Impedance Threshold Device During CPR Make a Difference?

In a randomized study, the device provided no survival benefit during out-of-hospital cardiac arrest.

The goal of cardiopulmonary resuscitation (CPR) is to establish and enhance cardiac output. Therefore, it seems rational that lowering intrathoracic pressure should promote venous return and improve circulation. The impedance threshold device (ITD) prevents inflow of air to the chest during chest recoil without impeding active ventilation and, thereby, prevents intrathoracic pressure from rising. In a cluster-randomized study, 9933 patients with nontraumatic out-of-hospital cardiac arrest at 10 Resuscitation Outcomes Consortium sites in the U.S. and Canada received standard CPR by emergency medical services (EMS) responders with use of an active ITD or a sham device placed within 5 minutes. The study was government funded, and ITDs were supplied by the manufacturer.

The primary outcome was the rate of discharge from hospital with satisfactory neurological function as measured by the modified Rankin score. Discharge status did not differ significantly between the group of patients who received the active device and those that received the sham device (5.8% and 6.0%). Neither intrathoracic pressure nor chest recoil was measured.


Aufderheide TP et al. A trial of an impedance threshold device in out-of-hospital cardiac arrest. N Engl J Med 2011 Sep 1; 365:798.