Abstract 46: Alternative Approaches to Ventilation by Emergency Medical Services after Prolonged Untreated Ventricular Fibrillation Cardiac Arrest: A Porcine Model Study
Introduction: It has recently been report in subjects with cardiac arrest that hyperventilation by physicians and emergency medical services (EMS) is common and potentially detrimental to survival.
Methods: Three different ventilation scenarios after prolonged untreated ventricular fibrillation (VF) were studied in a realistic swine model of out-of-hospital cardiac arrest relative to 24 hr neurologically normal survival. No bystander CPR was provided during the initial eight minutes of VF before the simulated arrival of EMS personnel. The animals were randomly assigned to one of three experimental ventilation protocols utilizing 100% oxygen plus continuous chest compressions at a metronome-directed rate of 100/min. Group I (standard ventilation) animals were mechanically ventilated at 10 respirations per minute (RPM) at a tidal volume (TV) of 10 ml/Kg. Group II (hyperventilation) animals were ventilated at 35 RPM at double the TV (20 ml/Kg.). Group III (insufflation) animals had oxygen (10 L/min) passively insufflated through a tube placed in the oropharynx.
Results: There were no significant differences among groups relative to return of spontaneous circulation or 24-hour neurological normal survival (standard: 2/12, hyperventilation: 2/12, insufflation: 4/12). There was no evidence of detrimental effects of hyperventilation.
Conclusions: Passive insufflation may be an acceptable approach to ventilation by EMS during resuscitation for out-of-hospital VF cardiac arrest. Advantages of this method are that it is easy to teach, administer and remember; it prevents the possible previously reported adverse effects of positive pressure ventilation and over-ventilation and allows EMS personnel to concentrate upon other critically important resuscitation procedures.