CPR techniques that combine chest and abdominal compression and decompression - Hemodynamic insights from a spreadsheet model

Background-This study was done to elucidate mechanisms by which newer cardi opulmonary resuscitation (CPR) techniques, including interposed abdominal c ompression (IAC), active compression-decompression (ACD), and Lifestick CPR , augment systemic perfusion pressure and forward flow and to compare the 3 techniques in the same test system. Methods and Results-Mathematical models describing hemodynamics of the adul t human circulation during cardiac arrest and CPR were created and exercise d by use of spreadsheet software. Assumptions of the models are limited to normal human anatomy and physiology, the definition of compliance (volume c hange/pressure change), and Ohm's law (flow = pressure/resistance). Standar d CPR generates 1.3 L/min forward and 25 !nm Hg systemic perfusion pressure . In otherwise identical models, IAC-CPR generates 2.4 L/min and 45 mm Hg; ACD-CPR, 1.6 L/min and 30 mm Hg; and Lifestick CPR, which combines IAC and ACD, 3.1 L/min and 58 mm Hg, Augmented CPR techniques work by enhanced prim ing of either chest or abdominal pump mechanisms. Conclusions-Adjunctive maneuvers, combined with conventional chest compress ion, can produce substantial hemodynamic benefit in CPR by credible physiol ogical mechanisms.