Abstract 19325: Hemodynamic Effects of Guideline-compliant Asynchronous vs. Synchronous Ventilations During Cardiopulmonary Resuscitation in a Porcine Model
Background: Current guidelines for cardiopulmonary resuscitation (CPR) emphasize reducing pauses in chest compressions, and suggest ventilating with 1 second inspiration time and with enough volume to produce normal chest rise 10 times per minute. No specific advice is provided on how ventilations should be timed with ongoing chest compressions. We have compared hemodynamic effects of ventilating synchronously vs. asynchronously during chest compressions in a porcine model.
Methods: Twenty anaesthetized domestic pigs (approx. 30 kg) were randomized into two groups; synchronous vs. asynchronous ventilation. Ventricular fibrillation is induced electrically and left for 2 minutes before initiation of basic 30:2 CPR for 4 minutes. CPR with continuous mechanical chest compressions was continued for another 8 minutes with either synchronous or asynchronous ventilation before defibrillation was attempted. Aortic, right atrial and intracerebral pressures, carotid and cerebral blood flow and cardiac output (thermodilution) were measured. Airway monitoring included capnography and spirometry.
Results: Hemodynamics, blood gas analysis and airway pressures were similar for both groups during baseline and 30:2 CPR periods. The asynchronous group had higher median peak inspiratory airway pressure (94 vs. 57 cm H2O, p<0.001) and lower EtCO2 (1.8 vs. 3.5 kPa, p=0.023) compared to synchronous group during the last 30 seconds of CPR (after 12 minutes). Asynchronous group also had higher pH (7.55 vs. 7.35, p<0.001), lower pCO2 (2.4 vs. 4.7, p<0.001) and higher pO2 (62.1 vs. 29.4, p<0.001) compared to synchronous group. There were no significant differences in any of the measured hemodynamic variables between the two groups with similar coronary and cerebral perfusion pressures. ROSC was achieved in 5/10 vs. 3/10 animals in the synchronous and asynchronous groups, respectively.
Conclusion: Synchronous and asynchronous ventilation during mechanical chest compressions provide similar hemodynamics, but guideline-compliant asynchronous ventilation yields significantly higher airway pressures and hyperventilation. Implications for lung injury need to be assessed.
Author Disclosures: C. Skåre: None. T. Olasveengen: None. J. Kramer-Johansen: None. F. Nordum: None. E. Morten: None. P. Norseng: None. M. Skjerven-Martinsen: None. L. Wik: None.
- © 2015 by American Heart Association, Inc.