Abstract 114: Chest Compression Release Velocity Does Not Affect Net Forward Flow but Does Affect Hydrodynamic Power in the Inferior Vena Cava
Introduction: Research has suggested that chest compression (CC) release velocity or waveform impacts CPR effectiveness. However, a detailed investigation of the impact of changes in CC waveform on blood flows and pressures during prolonged CPR has not been thoroughly investigated.
Methods: CPR hemodynamics in eight domestic swine (∼30 Kg) were studied using standard physiological monitoring. Flow probes were placed on the abdominal aorta, the inferior vena cava (IVC), the right renal artery and vein, the right common carotid and external jugular. Ventricular fibrillation (VF) was electrically induced. Mechanical CC were started after ten minutes of untreated VF. CC release was changed so that sternal recoil lasted 100 ms, 200 ms, or 300 ms. 54 min of CC were delivered at a rate of 100 per minute and at a depth of 1.25 in. Transitions between waveforms occurred every 2 min and were randomized.
Results: Analyses of the recorded hydrodynamic power (power = flow*pressure) indicated that there was a significant difference in the amount of energy each CC waveform transferred to the blood in the IVC (100 ms = 0.022±0.008, 200 ms = 0.020±0.008, 300 ms = 0.018±0.006 watts, p < 0.001 for all comparisons between waveforms). This difference was observed throughout the duration of testing. No significant differences were found between the amounts of net forward flow generated by each CC waveform in any vessel. Significant to and fro blood flow (sloshing) was observed during all chest compressions, regardless of CC waveform.
Conclusions: CC release velocity does not have a significant effect on net forward flow during a chest compression, but does have a significant effect on the amount of hydrodynamic power transferred to the blood in the IVC. Further research is required to determine how best to take advantage of the power difference between waveforms.
- © 2012 by American Heart Association, Inc.