Experience with Therapeutic Hypothermia in Out-of-Hospital Cardiac Arrest

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Abstract

Background: Out-of-hospital cardiac arrest (OHCA), one of the leading causes of death in the industrialized world, has a very low survival rate and high incidence of unfavorable neurological outcome among survivors, which have remained stable over the last three decades. The most recent clinical studies have proposed the usefulness of therapeutic hypothermia to reduce mortality and severity of unfavorable neurological outcome in OHCA survivors.
Objectives: The aim of this study was to evaluate the mortality and neurological status of comatose patients resuscitated from OHCA treated with therapeutic hypothermia, consider the indications and coronary angiography findings, and detect the complications associated with hypothermia.
Methods: Patients resuscitated from OHCA treated with therapeutic hypothermia were included in the study. The procedure consisted of cooling for 24 hours at a target temperature of 33°C followed by rewarming at 0.25°C/hour. The indications and coronary angiography findings were analyzed. The presence of metabolic disorders, arrhythmias, infections and bleeding were also evaluated.
A p value <0.05 was considered statistically significant. 
Results: The cohort consisted of 213 patients. In-hospital survival was 51.2% (n=109) and 46% of these cases (n=96) were discharged with favorable neurological status. Patients with shockable rhythms presented higher survival rates compared with those with non-shockable rhythms (58.2% vs. 37.7%; p=0.007). Coronary angiography was performed in 147 patients (69%) after a mean interval of 3.5 hours: 121 patients (82.3%) presented significant coronary artery disease and 69 patients (58%) had total occlusions. One-hundred and seven patients underwent percutaneous coronary intervention; among these patients 43 (40.2%) died during
hospitalization and 61 (58.6%) deaths were reported among those who did not undergo coronary angiography or interventional procedure (p=0.005). The most common complications were hypokalemia (87.6%) and sinus bradycardia (66.7%).
Conclusions: The use of therapeutic hypothermia was associated with in-hospital survival >50% and favorable neurological outcome in 46.1% of cases. Mortality was lower in patients undergoing percutaneous coronary intervention. Hypokalemia and sinus bradycardia were the most common complications.