Observed survival benefit of mild therapeutic hypothermia reanalysing the Circulation Improving Resuscitation Care trial

Eur J Clin Invest. 2017 Jun;47(6):439-446. doi: 10.1111/eci.12759. Epub 2017 May 16.

Abstract

Background: Mild therapeutic hypothermia is argued being beneficial for outcome after cardiac arrest.

Materials and methods: Retrospective analysis of Circulation Improving Resuscitation Care (CIRC) trial data to assess if therapeutic cooling to 33 ± 1 °C core temperature had an association with survival. Of 4231 adult, out-of-hospital cardiac arrests of presumed cardiac origin initially enrolled, eligibility criteria for therapeutic hypothermia were met by 1812. Logistic regression was undertaken in a stepwise fashion to account for the impact on outcome of each significant difference and for the variable of interest between the groups.

Results: Out-of- and in-hospital cooled were 263 (15%), only after admission cooled were 230 (13%) and not cooled were 357 (20%) patients. The group cooled out of- and in hospital had 98 (37%) survivors as compared to the groups cooled in hospital only [80 (35%)] and of those not cooled [68 (19%)]. After adjusting for known covariates (sex, age, witnessed cardiac arrest, no- and low-flow time, shockable initial rhythm, random allocation, bystander cardiopulmonary resuscitation and percutaneous coronary intervention), the odds ratio for survival comparing no cooling to out-of- plus in-hospital cooling was 0·53 [95% confidence interval (CI): 0·46-0·61, P < 0·001], and comparing to in-hospital cooling only was 0·67 (95% CI: 0·50-0·89, P = 0·006).

Conclusion: Mild therapeutic hypothermia initiated out of hospital and/or in hospital was associated with improved survival within this secondary analysis of the CIRC cohort compared to no therapeutic hypothermia.

Keywords: Cardiopulmonary resuscitation; heart arrest; resuscitation; survival; trials.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Cardiopulmonary Resuscitation / methods
  • Cardiopulmonary Resuscitation / mortality
  • Emergency Medical Services / statistics & numerical data
  • Female
  • Hospitalization / statistics & numerical data
  • Humans
  • Hypothermia, Induced / methods*
  • Hypothermia, Induced / mortality
  • Male
  • Middle Aged
  • Out-of-Hospital Cardiac Arrest / mortality
  • Out-of-Hospital Cardiac Arrest / therapy*
  • Retrospective Studies
  • Treatment Outcome