Impedance threshold device

An inspiratory impedance threshold device is a valve used in cardiopulmonary resuscitation (CPR) to decrease intrathoracic pressure and improve venous return to the heart. The valve is a part of a mask or other breathing device such as an endotracheal tube, and may open at high or low pressures (called "cracking pressures")^{[citation needed]}

Impedance threshold device
Specialty	Cardiology

Overview

ITDs are still in the early phases of clinical use, but preliminary investigational studies have suggested a potential benefit in achieving return of spontaneous circulation (ROSC) and early improvement after cardiopulmonary arrest in humans.^[1] More recently, the Resuscitation Outcomes Consortium (ROC) Prehospital Resuscitation Impedance Valve and Early Versus Delayed Analysis (PRIMED) study (n=8718) failed to demonstrate improved outcomes with the use of an impedance threshold device (ITD) as an adjunct to conventional CPR when compared with use of a sham device.

Quality of cardiopulmonary resuscitation (CPR) was a deciding factor, with ITD increasing survival when in combination with "acceptable" CPR quality, but decreasing survival when CPR quality was not "acceptable".^[2] This negative high-quality study prompted a Class III: No Benefit recommendation regarding routine use of the ITD.^[3]

ITD use may only be beneficial if the cardiac arrest is witnessed and the response time is rapid.^[4]