Abstract 13530: New Insights Into CPR Optimization Through a Flow per Compression Analysis of Chest Compression Generated Blood Flow

Introduction: During cardiac arrest and CPR, the two primary pumps of the cardiovascular circuit (the right and left ventricles) are supplanted by a single pump, the chest compression. In pre-clinical experiments, blood flows are reported as the amount of flow per minute (L/min). Characterizing flow on a per minute basis is highly dependent on chest compression (CC) rate. Analysis of flow generated by each compression (“cardiac output” in L/comp) could reveal important information relevant to lung perfusion and how the circuit as a whole is responding to CPR. Hypothesis: It was hypothesized that increasing CC rate would improve per minute blood flow but reduce flow on a per compression basis. Methods: CPR was performed on nine domestic swine (~30 kg) using standard monitoring. Flow was measured in the right common carotid and abdominal aorta. Ventricular fibrillation was electrically induced. Mechanical CC were started after ten minutes of untreated VF. CC were delivered at rates of 50, 75, 100, 125, or 150 compressions per minute (cpm) and a depth of 2” for a total of 54 min. CC rates were changed every 2 min and were randomized. Results: Mean blood flows are shown in L/min (solid line) and L/comp (dashed line) in Figure 1 for minutes 0-10 and 10-20. Across all rates, per minute flows were strongly rate dependent in minutes 0-10, favoring fast rates, and were weakly rate dependent in minutes 10-20, favoring rates near 100 CPM. Across all rates, per compression flow had a weaker rate dependence in minutes 0-10, favoring rates less than 100 CPM, but during minutes 10-20 had a strong rate dependence, also favoring rates less than 100 CPM. Conclusions: While CC rates greater than 100 cpm may provide more total blood flow early during CPR, analysis of blood flow per compression indicates that they can become detrimental after 10 minutes of ongoing CPR. During a prolonged resuscitation, a longer time after a given compression might be needed for venous refill thereby favoring rates of 100 cpm or less.