Despite the practice of standard closed-chest standard cardiopulmonary resuscitation for more than four decades, survival rates for patients in cardiac arrest remain dismally low. In recent years, several new cardiopulmonary resuscitation (CPR) techniques and devices have been developed to improve upon the relative inefficiencies of standard CPR. One technique, active compression-decompression (ACD) CPR, is based upon the concept that lowering intrathoracic pressure during the CPR decompression phase enhances venous return by 'priming the pump' for the next compression phase. ACD CPR can significantly improve short- and long-term survival rates over standard CPR if performed by well-trained rescue personnel. Building upon ACD CPR, an inspiratory impedance threshold valve has more recently been developed that further decreases decompression phase intrathoracic pressure. The ITV(TM) and ACD CPR in combination provide even greater benefit over standard CPR or ACD CPR alone. These devices are becoming more widely accepted and used. (C) 2000 Lippincott Williams and Wilkins, Inc.