Therapeutic hypothermia after cardiac arrest: a retrospective comparison of surface and endovascular cooling techniques

Abstract

Objectives: Therapeutic hypothermia (32-34 degrees C) is recommended for comatose survivors of cardiac arrest; however, the optimal technique for cooling is unknown. We aimed to compare therapeutic hypothermia using either surface or endovascular techniques in terms of efficacy, complications and outcome.

Design: Retrospective cohort study.

Setting: Thirty-bed teaching hospital intensive care unit (ICU).

Patients: All patients (n=83) undergoing therapeutic hypothermia following cardiac arrest over a 2.5-year period. The mean age was 61+/-16 years; 88% of arrests occurred out of hospital, and 64% were ventricular fibrillation/tachycardia.

Interventions: Therapeutic hypothermia was initiated in the ICU using iced Hartmann's solution, followed by either surface (n=41) or endovascular (n=42) cooling; choice of technique was based upon endovascular device availability. The target temperature was 32-34 degrees C for 12-24 h, followed by rewarming at a rate of 0.25 degrees Ch(-1).

Measurements and main results: Endovascular cooling provided a longer time within the target temperature range (p=0.02), less temperature fluctuation (p=0.003), better control during rewarming (0.04), and a lower 48-h temperature load (p=0.008). Endovascular cooling also produced less cooling-associated complications in terms of both overcooling (p=0.05) and failure to reach the target temperature (p=0.04). After adjustment for known confounders, there were no differences in outcome between the groups in terms of ICU or hospital mortality, ventilator free days and neurological outcome.

Conclusion: Endovascular cooling provides better temperature management than surface cooling, as well as a more favorable complication profile. The equivalence in outcome suggested by this small study requires confirmation in a randomized trial.