Objective:To compare the efficacy of four methods of simulated single-rescuer bystander cardiopulmonary resuscitation (CPR) in a clinically relevant swine model of prehospital pediatric asphyxial cardiac arrest.Design:Prospective, randomized study.Subjects:Thirty-nine anesthetized domestic piglets.Interventions:Asphyxial cardiac arrest was produced by clamping the endotracheal tubes of the piglets. For 8 mins of simulated bystander CPR, animals were randomly assigned to the following groups: group 1, chest compressions and simulated mouth-to-mouth ventilation (FIO2= 0.17, FICO2= 0.04) (CC+V); group 2, chest compressions only (CC); group 3, simulated mouth-to-mouth ventilation only (V); and group 4, no CPR (control group). Standard advanced life support was then provided, simulating paramedic arrival. Animals that were successfully resuscitated received 1 hr of intensive care support and were observed for 24 hrs.Measurements and Main Results:Electrocardiogram, aortic blood pressure, right atrial blood pressure, and end-tidal CO2were monitored continuously until the intensive care period ended. Arterial and mixed venous blood gases were measured at baseline, 1 min after cardiac arrest, and 7 mins after cardiac arrest. Minute ventilation was determined during each minute of bystander CPR. Survival and neurologic outcome were determined. Twenty-four-hour survival was attained in eight of 10 group 1 (CC+V) piglets vs. three of 14 group 2 (CC) piglets (p≤ .01), one of seven group 3 (V) piglets (p≤ .05), and two of eight group 4 (control) piglets (p≤ .05). Twenty-four-hour neurologically normal survival occurred in seven of 10 group 1 (CC+V) piglets vs. one of 14 group 2 (CC) piglets (p≤ .01), one of seven group 3 (V) piglets (p≤ .05), and none of eight group 4 (control) piglets (p≤ .01). Arterial oxygenation and pH were markedly better during CPR in group 1 than in group 2. Within 5 mins of bystander CPR, six of 10 group 1 (CC+V) piglets attained sustained return of spontaneous circulation vs. only two of 14 group 2 (CC) piglets and none of the piglets in the other two groups (p≤ .05 for all groups).Conclusions:In this pediatric asphyxial model of prehospital single-rescuer bystander CPR, chest compressions plus simulated mouth-to-mouth ventilation improved systemic oxygenation, coronary perfusion pressures, early return of spontaneous circulation, and 24-hr survival compared with the other three approaches.