Temperature management and its role in cardiac arrest patients—a review

Thermoregulation constitutes one of the most important homeostatic systems of the human body. The human thermoregulatory system is highly complex and intertwined with other regulatory homeostatic systems. Different evolutionary adaptations have evolved to ensure a well-regulated body temperature, encompassing simple behavioural (e.g., seeking shelter, going underground) as well as physiological changes (e.g., vasodilatation, sweating). However, when the heat, cold or other stimuli cause a disruption in the thermoregulatory state and our adaptations can no longer cope with the additional stress, the body enters a pathological state. In such instances other measures must be undertaken. In medicine there are several pathological states associated with disruptions in temperature homeostasis. Consequently, these patients have to be, in broad terms, thermoregulated. Speaking specifically, the most common application of thermoregulation is therapeutic temperature management. A prominent example is the utilisation of this technique in post-cardiac arrest patients, who remain comatose after resuscitation. This technique has been in use for almost 20 years since the first major reports on its benefits in improving out-of-hospital cardiac arrest and in-hospital cardiac arrest survival as well as improving neurological outcome. Recently, the findings from one of the biggest targeted temperature international and multicentre trials to date have been published (TTM2 trial; https://ttm2trial.org/). The study surprisingly showed no difference in mortality between patients after out of hospital cardiac arrest, who underwent normo- or hypothermia. Consequently, we might need to re-evaluate certain guidelines, recommendations, and perspectives. The aim of the current review is to present an overview of targeted temperature management in the field of intensive care medicine and cardiac arrest.