Abstract 34: The Effects of an Automatic Low Pressure Ventilation Device versus Manual Ventilation During Cardiopulmonary Resuscitation in a Porcine Model of Cardiac Arrest
Background: The Oxylator® is an automatic, pressure powered, flow triggered ventilation device which delivers pressure and flow limited gas when expiratory flow falls to < 2 L/min (approximately 2 cmH2O of airway PEEP). The effects of this device on hemodynamics and gas exchange during CPR have not been evaluated.
Methods: Twelve Yorkshire pigs (35–45 kg) each underwent 3 episodes of 30 second untreated VF followed by 5 minutes of CPR: 90 piston driven mechanical chest compressions/min and three different ventilation types in balanced random order:
manual ventilation with an Ambu® bag (12 breaths/min),
OxylatorP15F20 (max. pressure 15 cmH2O, constant flow 20 L/min) and
OxylatorP20F30 (max. pressure 20 cmH2O, constant flow 30 L/min).
Aortic, right atrial, esophageal (to estimate pleural pressure) and airway pressures were continuously recorded. ETCO2 and O2 saturation were measured every minute. Arterial blood gases were collected before induction of VF (baseline) and at the end of each 5 minute CPR episode. The animals were then defibrillated with 200J, 250J, 300J or 360J × 3 times, as needed. VF episodes were repeated at 20–30 minute intervals. There were no other therapeutic interventions before, during or after CPR.
Results: Coronary perfusion pressure (CPP, diastolic; aortic minus right atrial pressure), end-tidal CO2 (ETCO2), the partial pressure of CO2 (pCO2), the partial pressure of O2 (pO2), trough of esophageal pressure (EsoP-t), trough of airway pressure (AirwayP-t) and peak airway pressure (AirwayP-p) are presented in the table⇓. The threshold for defibrillation and peak esophageal pressure (EsoP-p) are not different among the groups.
Conclusion: Automated pressure and flow limited ventilation during CPR results in higher coronary perfusion pressure and ETCO2 than manual ventilation, despite continuously positive airway pressure.