Abstract 2414: Intra-arrest Hypothermia: Both Cold Liquid Ventilation with Perfluorocarbons and Cold Intravenous Saline Rapidly Achieve Hypothermia, but Only Cold Liquid Ventilation Improves Resumption of Spontaneous Circulation
Background Intra-arrest induction of hypothermia using total liquid ventilation (TLV) with cold perfluorocarbons (PFC) rapidly induces moderate hypothermia and improves resuscitation outcome. Cold saline intravenous infusion during cardiopulmonary resuscitation (CPR) is an effective and simpler method of inducing hypothermia. Our aim was to compare two methods of rapid hypothermia induction - cold TLV versus cold intravenous saline - in a large animal model of ventricular fibrillation (VF) cardiac arrest and resuscitation.
Methods Twenty-four female swine were divided into three groups: cold TLV (TLV, n=8), cold saline infusion (S, n=8), and control (C, n=8). VF was electrically induced in all animals and allowed to persist without defibrillation for 14 minutes. Beginning at 8 minutes of VF, TLV and S animals received 3 minutes of cold TLV or rapid cold normal saline infusion (30cc/kg over 98 ± SD 6 seconds). C animals underwent no intervention. After 11 minutes of VF, all groups received standard air ventilation and closed chest massage. Defibrillation was attempted after 3 minutes of CPR (14 minutes of VF) and repeated each minute as necessary for persistent or recurrent VF. Resuscitation continued until resumption of spontaneous circulation (ROSC) or for a minimum of 11 minutes (22 minutes after VF induction).
Results Pulmonary arterial (PA) temperature decreased after 1 minute of CPR from 37.2°C to 32.2°C in S animals, from 37.1°C to 34.8°C in TLV animals, and did not change in C animals (S or TLV vs. C p<0.0001). Mean PA temperature remained lower in S and TLV animals versus C for the entire CPR period. ROSC was achieved in 7 of 8 (88%) TLV, 2 of 8 (25%) S, and 1 of 8 (13%) C. A significant difference in ROSC was observed between TLV and C (p=0.03), while there was not a difference in ROSC between S and C.
Conclusions Moderate hypothermia was achieved rapidly during VF and CPR using both cold saline infusion and cold PFC total liquid ventilation, but ROSC was higher than control only in animals treated with cold TLV. Further studies are necessary to delineate the mechanism by which TLV with PFC improves resuscitation outcome from VF arrest.