Abstract 2659: Effect of an Automated Ventilator and the Impedance Threshold Device on Coronary Perfusion Pressure and Cerebral Blood Flow During Cardiopulmonary Resuscitation in Pigs
The impedance threshold device (ITD) increases coronary perfusion during CPR by lowering intrathoracic pressure during decompression. The effect of an automatic ventilator which cycles when expiratory flow drops to nearly zero (cycling on each decompression) on hemodynamics during CPR with or without the ITD has not been evaluated.
Methods and Results: The effects of
an automated pressure and flow limited ventilator (Oxylator®, limit 25 cm H2O and 30 l/min), each alone and
in combination, and
manual ventilation (control), during active compression decompression CPR (80 compressions/min) was assessed in 12 closed chest anesthetized pigs during ventricular fibrillation (VF).
After 2 minutes of VF, pigs were treated for 4 minutes with one of the 4 treatments and then defibrillated. Thus, each animal underwent 4 episodes of VF in balanced random order. Coronary perfusion pressure (CPP; aortic-right atrial pressure), LV pressure, and airway pressure, as well as relative cerebral blood flow (rCBF, laser Doppler Flowmetry) were measured at the end of each VF period. rCBF was reported as a ratio relative to the baseline for each VF episode. CPP was highest with the ITD, whereas cerebral blood flow estimate was highest after the Oxylator®. CPP: coronary perfusion pressure, AirPeakP: maximum airway pressure, AirMinP: minimum airway pressure, LVPP: left ventricular peak pressure, AOPP: aortic peak pressure, rCBF ratio to baseline, CSDE: cumulative successful defibrillation energy. * Manual + ITD vs. any other group, p<0.0001; Δ Manual or Manual + ITD vs. Oxylator or Oxylator + ITD, p<0.0001; † Oxylator vs. Manual or Oxylator + ITD, p=0.0018.
Conclusion: Despite a higher nadir of airway pressure during decompression, coronary perfusion pressure and brain blood flow are higher with the ITD or Oxylator® relative to manual ventilation during pressure and flow limited automated ventilation. The ITD achieves the highest coronary perfusion pressure during CPR.