Harnessing biphasic changes in intrathoracic pressure to improve cardiac arrest outcomes

Understanding the physiology of blood flow to the brain and heart during cardiopulmonary resuscitation (CPR) is an essential first step in improving outcomes after cardiac arrest Over the past 20 years much has been learned about the importance of carefully modulating pressures inside the thorax to optimize perfusion to the heart and brain during CPR. When compressions are too fast, too slow, too deep, or too shallow, outcomes are worsened. Full chest wall recoil is also essential to refill the heart after each compression. Furthermore, changes in intrathoracic pressure are immediately transmitted to the brain: elevated thoracic pressures increase intracranial pressure and thus reduce brain perfusion. The opposite is also true. New devices such as the impedance threshold device (ITD) have been designed to harness the recoil of the chest during CPR and thereby lower intrathoracic pressures. The small vacuum that develops with conventional CPR is augmented by the ITD during conventional CPR, active compression-decompression (ACD) CPR, and when CPR is delivered by automated chest compression devices. Use of the combination of ACD CPR plus the ITD has been shown to significantly improve short- and long-term outcomes, with favorable brain function, after cardiac arrest This approach is synergistic with advances in therapeutic hypothermia, mechanical means to provide continuous chest compressions, and other improvements in post-resuscitation care. It is now time to move away from conventional CPR with a pair of hands and utilize new approaches.