Abstract 2704: Efficacy of Early Induction of Hypothermia Using Intravenous Ice-cold Fluids (J-PLUSE-Hypo registry) and Its Optimal Monitoring Places of Core Temperature
Background Animal studies showed that very early induction of hypothermia was beneficial to neurological outcome. Intravenous ice-cold fluids alone cannot be used to maintain hypothermia, but this cooling method can be used to institute easily and inexpensively.
Methods The J-PLUSE-Hypo was conducted as a multi-center hypothermia study. We added a study of optimal monitoring places of core temperature during intravenous 2000mL of normal saline at 4°C using high-pressure infusion bags to the J-PLUSE-Hypo. In our additional study, esophagus, rectum and bladder temperature were monitored as core temperatures. The primary endpoint of the J-PLUSE-Hypo was a favorable neurological outcome in 30 days survival.
Results In the J-PULSE-Hypo, 165 patients with return of spontaneous circulation after out-of-hospital ventricular fibrillation cardiac arrest were treated with mild hypothermia (34°C for 1 to 3 days). Of those, 74 were treated with intravenous ice-cold fluids in combination with other cooling methods (IV group) and 91 induced hypothermia using external or extracorporeal cooling method (no-IV group). The two groups had similar cooling-to-34°C interval (median; 168 min vs. 195 min, p = 0.68), but a significant difference was seen in a favorable neurological outcome between the two groups (72% vs. 52%, p = 0.009). In those patients, a core temperature was monitored by bladder, rectum or pulmonary artery temperature during the maintenance of hypothermia. In our additional study, a mean administrated interval of ice-cold fluids was 14 minutes. Significant differences were seen in the core temperatures before and after initiation of ice-cold fluids among the three monitoring places (before ice-cold fluids; 34.4±2.3°C in the esophagus vs. 37.0±1.2°C in the rectum vs. 36.5±1.2°C in the bladder, p < 0.001: after 30 minutes of ice-cold fluids; 32.5±2.5°C in the esophagus vs. 34.8±1.7°C in the rectum and 35.0±1.5°C in the bladder, p < 0.001).
Conclusions Early induction of hypothermia using intravenous ice-cold fluids was associated with better neurological outcomes. During ice-cold fluids, the esophagus temperature was not suitable as a core temperature monitoring and its temperature created an overestimation.