Abstract 13264: Varying Ventilation Strategies During Cardiac Arrest Has Minimal Impact on Hemodynamics

Abstract

Introduction: Prolonged duty cycle ventilation and hyperventilation are associated with reduced venous return during CPR. Meanwhile, the 30:2 compressions-ventilation method requires pauses in compressions, which could also negatively affect hemodynamics. We investigated the effect of varying ventilation strategies on hemodynamics in a swine model of cardiac arrest. Hypothesis: Continuous ventilations with a short duty cycle, as compared to longer duty cycles and standard 30:2 ventilation, would be associated with improvements in hemodynamics. Methods: CPR was performed on eight domestic swine (~30 kg) using standard physiological monitoring. Blood flow was measured in the inferior vena cava (IVC). Ventricular fibrillation (VF) was electrically induced. Mechanical chest compressions (CC) were started after four minutes of VF. CC were delivered at a rate of 100 compressions per minute and a depth of 2” for a total of 12 min. Animals were intubated and mechanically ventilated throughout the experiment. Three ventilation strategies were tested: 1) continuous ventilator-driven ventilation (CV-DV) at a rate of 6 breaths per minute and a 0.20 duty cycle, 2) CV-DV at a rate of 6 breaths per minute and a 0.50 duty cycle, and 3) standard 30:2 at a 0.20 duty cycle. All tidal volumes were calculated as 7 ml/kg. PEEP was set to zero for all ventilations. Results: Across 12 minutes of CPR, aortic pressure and coronary perfusion pressure was greater with CV-DVs of 0.20 and 0.50 duty cycle as compared to 30:2 (Table). Overall net flow in the IVC was not different among ventilation strategies. Conclusions: As compared to the 30:2 method, CV-DVs at 0.20 and 0.50 duty cycles produced small increases in blood pressures but no changes in venous return. Further research is needed to determine if hemodynamics can be improved by synchronizing continuous ventilations to CC and if this association reflects elimination of the interruptions in chest compressions.