Abstract 2538: Continuous Chest Compression Resuscitation in Arrested Swine With Upper Airway Inspiratory Obstruction
Background: The appropriateness of the swine model to emulate human cardiopulmonary resuscitation (CPR) has been questioned, in part because of differences in the upper airway patency. This study was designed to evaluate the survival rates of swine in cardiac arrest treated with a ratio of 30 compressions to 2 ventilations (30:2 CPR) algorithm with two different continuous chest compression (CCC) algorithms, one with and the other without complete inspiratory airway obstruction.
Methods: Thirty swine were randomly assigned among three experimental groups to receive either 30:2 CPR with an unobstructed endotracheal tube (ET) or continuous chest compression (CCC) CPR with an unobstructed ET or CCC CPR with a collapsable rubber sleeve on the ET allowing air outflow but completely restricting air inflow. Two min of untreated VF was followed by 9 min of simulated single rescuer bystander CPR. In the 30:2 CPR group, each set of 30 chest compressions was followed by a 15 second pause to simulate a single rescuer delivering 2 mouth-to-mouth ventilations. The other 2 groups received no assisted ventilations. At 11 minutes post-arrest a biphasic defibrillation shock (150 Joules) was administered followed immediately by 200 chest compressions. An advanced cardiac life support protocol was then followed. Survival and neurologic status were evaluated at 24 hrs post-resuscitation.
Results: In the 30:2 group 8 of 10 animals had return of spontaneous circulation (ROSC) and 8 had good neurological function at 24-hrs post-resuscitation. In the CCC open airway group 10 of 10 had ROSC and all had good neurologic function at 24 hours. In the CCC-inspiratory obstructed group, 10 of 10 attained ROSC 9 had good neurologically function and 1 was neurologically impaired at 24 hrs post-resuscitation. The number of shocks (P<0.05) and epinephrine doses (P<0.05) required for ROSC was greater in the 30:2 CPR group than in the other two groups.
Conclusions: There were no differences in 24-hr survival with good neurological function using the three different CPR protocols. During the first 11 minutes of cardiac arrest, differences in upper airway dynamics in this study did not affect resuscitation success or neurological function at 24-hr post resuscitation.