Introduction:
Every year about 70% of coronary heart disease deaths in the United States occur out of hospital, usually presenting as ‘sudden death’ due to cardiac arrest. Despite the improvement of survival with advanced cardiac interventions, mortality remains high. Therapeutic hypothermia (TH) has been shown to be neuroprotective after cardiac arrest. We explored factors associated with good recovery of neurological function following out-of-hospital cardiac arrest (OHCA).
Methods:
This retrospective study included review of electronic medical records from a major healthcare system in Northeast Indiana. Individuals who suffered OHCA from January 2011 to June 2014 were included. Neurological function was evaluated by Modified Rankin Scale (mRS) at discharge. The neurological outcome was defined as good (mRS 0-3), poor (mRS 4-5), and deceased (mRS 6) to assess the association of examined variables.
Results:
Among the 111 patients meeting inclusion criteria, the mortality at discharge was 68.6% in TH-treated patients and 84% in normothermia patients. For almost half (47.5%) of the patients undergoing TH who died prior to discharge, brain-related causes were the primary cause of death. 21 patients who had imaging or pathological examinations all showed evidences of ischemic brain injury. Among TH-treated survivors, patients with return of spontaneous cardiac rhythm (ROSC) within 20 minutes of onset were 1.4 times the odds more likely to have a good neurological outcome at discharge (p=0.02). Patients with ventricular fibrillation had 2 times the odds more likely retaining good neurological function at discharge after receiving TH treatment (p=0.012). The time to initiate TH (mean 2.3 ± 1.5 hours) and time to reach target temperature (mean 7.2 ± 2.3 hours) were not associated with neurological outcome at discharge.
Conclusions:
Initial rhythm and time to ROSC were identified as reliable predictors of good neurological function following OHCA. TH has been found to be insufficient in preventing brain injury. This study emphasizes the need for future studies to develop new neuroprotective strategies to improve survival among OHCA patients.
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