Comparison of 1-year neurological outcome between intra-hospital and extra-hospital cardiac arrest survivors submitted to mild therapeutic hypothermia in a community-based setting in Brazil

Introduction

Mild therapeutic hypothermia (MTH) is the most powerful therapy to improve survival and neurologic outcome after out-of-hospital cardiac arrest. Such benefit may also occur for unconscious patients after in-hospital cardiac arrest. The aim is to compare 1-year evolution of neurological outcomes of patients treated with MTH after in-hospital versus out-of-hospital cardiac arrest.

Methods

A prospective study of patients treated with MTH after cardiac arrest in a community hospital in São Paulo, Brazil. After return of spontaneous circulation, unconscious survivors received MTH using topical ice and cold saline infusions in order to achieve a 32 to 34°C goal temperature, within 6 hours of cardiac arrest, and maintained for 24 hours. Esophageal temperature was monitored; continuous intravenous sedation-analgesia was maintained for 48 hours after initiation of MTH. The Glasgow Outcome Scale (GOS) was used to analyze the neurological outcomes after hospital discharge.

Results

From January 2009 to April 2012, 84 patients submitted to MTH were divided into two groups: Group 1, 54 patients presented out-of-hospital cardiac arrest; and Group 2, 30 patients had intra-hospital cardiac arrest. Both groups were similar regarding to gender; Group 2 tended to be older (mean age 44.3 years vs. 33.5 years, P = 0.07), and had more frequently asystole as the cardiac arrest rhythm (45% vs. 15 %, P = 0.10). Group 2 had shorter duration of resuscitation (12.3 minutes vs. 33.7 minutes, P = 0.03), longer time to hypothermia initiation (309.3 minutes vs. 212.8 minutes, P = 0.04), longer hospital stay after cardiac arrest (50.7 days vs. 32.4 days, P = 0.01) and worse neurological outcome, characterized by the presence of GOS ≤3 at 30 days (68.4% vs. 35.1%, P = 0.03). Hospital mortality was 5.5% in Group 1 and 13.3% in Group 2 (P = 0.21). The 1-year survival rate was 85.1% in Group 1 and 83.3% in Group 2 (P = 0.43); after 13year follow-up, GOS ≤3 was present in 30.4% of Group 2 patients and in 11.1% of Group 1 patients (P = 0.04).

Conclusion

Midterm neurological outcome of MTH after in hospital cardiac arrest seems to be not as good as after out-of-hospital cardiac arrest. Delay in hypothermia initiation, older age and associated comorbidities could explain the worse evolution of this group of patients.