Clinical Investigations Clinical evaluation of an inspiratory impedance threshold device during standard cardiopulmonary resuscitation in patients with out-of-hospital cardiac arrest*

An inspiratory impedance threshold device (ITD) has recently been demonstrated to enhance vital organ perfusion and neurologically intact survival rates in animals in cardiac arrest during standard cardiopulmonary resuscitation (CPR) (1– 4). The ITD is a small, 35-mL device that can attach to a variety of airway adjuncts, including a facemask and endotracheal tube (Fig. 1). By selectively impeding inspiratory gas exchange during the decompression phase of CPR, the ITD lowers intrathoracic pressure and enhances venous blood return to the heart. Building on animal studies, we tested the hypothesis that the ITD would increase short-term survival rates in patients receiving CPR for treatment of out-ofhospital cardiac arrest, even when applied late in resuscitation.