Effect of Hydrogel Pad and Conventional Method on the Induction Time of Therapeutic Hypothermia in Patients with Out-of-Hospital Cardiac Arrest

Chung, Ga Young; Lee, Tae Rim; Choi, Dae Jong; Lee, Sung Su; Kang, Mun Ju; Cha, Won Chul; Shin, Tae Gun; Sim, Min Seob; Jo, Ik Joon; Song, Keun Jeong; Jeong, Yeon Kwon

Abstract

BACKGROUND
Therapeutic hypothermia has been recommended as a standard treatment of cardiac arrest patients after return of spontaneous circulation. There are various methods to drop patient's core body temperature below 33.5degrees C. We compared the cooling rate of the conventional cooling method using cold saline bladder irrigation with the commercial hydrogel pad in out-of-hospital cardiac arrest (OHCA) patients.
METHODS
We collected data retrospectively from the Samsung Medical Center hypothermia database. The conventional method group was cooled with IV infusion of 2,000 ml of 4degrees C cold saline and cold saline bladder irrigation. Patients in the hydrogel pad group had their body temperature lowered with the Artic Sun(R) after receiving 2,000 ml of 4degrees C cold saline intravenously. The induction time was defined as time from cold saline infusion to the esophageal core temperature below 33.5degrees C. The esophageal temperature probe insertion to the target temperature time (ET to target BT time) was defined as the time from the esophageal probe insertion to the core temperature below 33.5degrees C. We compared these times and cooling rates between the two groups.
RESULTS
Eighty one patients were enrolled. Fifty seven patients were included in the hydrogel pad group and 24 patients were in the conventional group. There were no statistical differences of baseline characteristics between the two groups. The induction time of the conventional group (138 min., IQR 98-295) was shorter than that of the hydrogel pad group (190 min., IQR 140-250). The ET to target BT time of the conventional group (106 min., IQR 68-249) was shorter than that of the hydrogel pad group (163 min., IQR 108-222). The cooling rate of the conventional group (0.93degrees C/hr., IQR 0.58-2.08) was lower than that of the hydrogel pad group (1.05degrees C/hr., IQR 0.74-1.96). However, there were no statistical differences in the induction time, the ET to target BT time and the cooling rate between the two groups.
CONCLUSIONS
There was no significant statistical difference of the cooling rate of the hydrogel pad and conventional method on the induction time of therapeutic hypothermia in Patients with OHCA. The conventional cooling method can be used as an effective and efficient way to lower OHCA patient's core body temperature during the induction phase of therapeutic hypothermia.