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☆

Abstract 

Background

Rapid intra-arrest induction of hypothermia using total liquid ventilation (TLV) with cold perfluorocarbons improves resuscitation outcome from ventricular fibrillation (VF). Cold saline intravenous infusion during cardiopulmonary resuscitation (CPR) is a simpler method of inducing hypothermia. We compared these 2 methods of rapid hypothermia induction for cardiac resuscitation.

Methods

Three groups of swine were studied: cold preoxygenated TLV (TLV, n=8), cold intravenous saline infusion (S, n=8), and control (C, n=8). VF was electrically induced. Beginning at 8min of VF, TLV and S animals received 3min of cold TLV or rapid cold saline infusion. After 11min of VF, all groups received standard air ventilation and closed chest massage. Defibrillation was attempted after 3min of CPR (14min of VF). The end point was resumption of spontaneous circulation (ROSC).

Results

Pulmonary arterial (PA) temperature decreased after 1min of CPR from 37.2°C to 32.2°C in S and from 37.1°C to 34.8°C in TLV (S or TLV vs. C p<0.0001). Coronary perfusion pressure (CPP) was higher in TLV than S animals during the initial 3min of CPR. Arterial pO₂ was higher in the preoxygenated TLV animals. ROSC was achieved in 7 of 8 TLV, 2 of 8 S, and 1 of 8C (TLV vs. C, p=0.03).

Conclusions

Moderate hypothermia was achieved rapidly during VF and CPR using both cold saline infusion and cold TLV, but ROSC was higher than control only in cold TLV animals, probably due to better CPP and pO₂. The method by which hypothermia is achieved influences ROSC.

Abbreviations: TLV, total liquid ventilation, PFC, perfluorocarbons, VF, ventricular fibrillation, CPR, cardiopulmonary resuscitation, ROSC, resumption of spontaneous circulation, PA, pulmonary artery, CPP, coronary perfusion pressure, HR, heart rate, MAP, mean arterial pressure, CO, cardiac output, MPAP, mean pulmonary arterial pressure, PCWP, pulmonary capillary wedge pressure, CPP, coronary perfusion pressure

Keywords: Hypothermia, Cardiopulmonary resuscitation, Ventricular fibrillation, Perfluorocarbons