A Trial of an Impedance Threshold Device in Out-of-Hospital Cardiac Arrest

Patients with out-of-hospital cardiac arrest were assigned to the use of either an impedance threshold device (ITD) or a sham ITD. There was no significant difference between the two groups in survival to hospital discharge with satisfactory functional status. Standard cardiopulmonary resuscitation (CPR), defined as manual chest compressions with rescue breathing, can be lifesaving but provides only a relatively small fraction of normal cardiac output, even when performed correctly. 1 , 2 One proposed strategy to augment cardiac output during CPR is the use of an impedance threshold device (ITD). 3 – 5 The ITD is designed to enhance venous return and cardiac output during CPR by increasing the degree of negative intrathoracic pressure (Fig. 1 in the Supplementary Appendix, available with the full text of this article at NEJM.org). This effect is achieved by preventing the passive inflow of air into the chest . . .