Changes in Practice of Controlled Hypothermia After Cardiac Arrest in the Past 20 Years - A Critical Care Perspective.

Abstract

For 20 years induced hypothermia and targeted temperature management (TTM) have been recommended to mitigate brain injury and increase survival after cardiac arrest. Based on animal research and small clinical trials the International Liaison Committee on Resuscitation strongly advocated hypothermia at 32-34°C for 12-24 hours for comatose out-of-hospital cardiac arrest patients with initial rhythm ventricular fibrillation or non-perfusing ventricular tachycardia. The intervention was implemented world-wide. The last decade hypothermia and TTM have been investigated in larger clinical randomized trials with focus on target temperature depth, target temperature duration, pre-hospital initiation versus in-hospital initiation, in non-shockable rhythms, and in in-hospital cardiac arrests. Systematic reviews suggest little or no effect of delivering the intervention based on the summary of evidence and ILCOR today recommends to only treat fever and keep temperatures below 37.5°C (weak recommendation, low certainty evidence). Here we describe the evolution of temperature management for cardiac arrest patients during the last 20 years and how the accrued evidence has influenced not only the recommendations but also the guideline process. We also discuss possible paths forward in this field, both bringing up whether fever management at all is beneficial for cardiac arrest patients, and which knowledge gaps future clinical trials in temperature management should address.