What is hypothermia?
In intensive care units (ICUs), the term targeted temperature management (TTM), as used in the current literature, is now preferred over incomplete or outdated terms such as ‘hypothermia’ or ‘therapeutic hypothermia’.
TTM involves bringing the patient's body temperature to a planned target and maintaining it there, then returning to normothermia in a controlled way and preventing fever. The target temperature depends on the patient group: after cardiac arrest in adults, a target between 32 and 37.5 °C with fever prevention; in neonatal HIE, 33.5 °C; and in acute brain injury, controlled normothermia.
What do the 2025 guidelines recommend?
The AHA 2025 guideline recommends that, in adults who do not follow commands after cardiac arrest, temperature be controlled between 32 and 37.5 °C for at least 36 hours, and that rewarming after hypothermia not exceed 0.5 °C per hour. The ERC-ESICM 2025 guideline recommends preventing fever (above 37.7 °C) for at least 72 hours in comatose patients. Both guidelines emphasise continuous core temperature monitoring; if a device is used for fever prevention, a feedback-controlled (servo-controlled) device is recommended. Routine hypothermia at 33 °C has not been shown to be superior to normothermia with fever prevention (TTM2, 2021); the target is set by the physician according to the patient.
Why is hypothermia treatment important?
Our growing knowledge of high-mortality conditions such as sudden cardiac arrest (CA), which affects hundreds of thousands of people worldwide and in our country every year, is helping us make progress in these cases with a very poor prognosis. Adopting current approaches in basic and advanced life support and investing effort in care after cardiopulmonary resuscitation (CPR) are therefore very important. The last link in the chain of survival after cardiac arrest is post-resuscitation care, and the aim of treatment in this period is to improve quality of life. In cardiac arrest, mortality and morbidity are determined primarily by neurological survival. One of the leading neuroprotective strategies in post-resuscitation care is targeted temperature management (TTM).
PATIENT SELECTION FOR TTM
The main guideline-supported uses of TTM are coma after cardiac arrest and neonatal hypoxic-ischaemic encephalopathy (HIE). It is also used for fever control and controlled normothermia in acute brain injuries such as traumatic brain injury, stroke, and intracerebral and subarachnoid haemorrhage, and for controlled rewarming after cardiac surgery. A benefit of hypothermia has not been shown in cardiogenic shock or sepsis; in these patients the aim, where needed, is normothermia and fever control.
When should targeted temperature management (TTM) be started in adults?
TTM should be started as soon as possible after return of spontaneous circulation (ROSC) following cardiac arrest, to minimise reperfusion injury. In Türkiye, the Health Implementation Communiqué (SUT) reimburses treatments started within 12 hours.
Is advanced age an exclusion criterion for hypothermia treatment (TTM)?
Since the main aim of this treatment is to improve the chance of a good neurological outcome in surviving patients, advanced age alone should not be an exclusion criterion. In patients aged 75 and over, the decision should be made by considering the patient's overall condition together with the risks of treatment.
What are the patient selection criteria for hypothermia treatment in the Health Implementation Communiqué (SUT)?
Targeted temperature management (TTM) is applied in healthcare providers with a level-three neonatal/paediatric intensive care unit or a level-two/three adult intensive care unit, in patients diagnosed with hypoxic-ischaemic encephalopathy or in comatose patients (Glasgow Coma Scale < 9) with return of spontaneous circulation after cardiopulmonary resuscitation, provided that it is started within the first 12 hours, for a maximum of 72 hours, and only in level-three neonatal/paediatric and level-two/three adult intensive care units. It may be billed in addition to the neonatal/paediatric or adult intensive care procedure score up to three times during the same hospital stay.
Which newborns receive hypothermia treatment?
According to the American Academy of Pediatrics (AAP) 2026 clinical report, therapeutic hypothermia is given to infants born at 36 weeks' gestation or later who have biochemical evidence of a hypoxic-ischaemic event around birth and moderate-to-severe encephalopathy or seizures on neurological examination. Treatment is ideally started within the first 6 hours, maintained at 33.5 °C for 72 hours, and servo-controlled cooling is preferred. It may be considered in infants born at 35 weeks after shared decision-making with the family; it is not routinely recommended below 35 weeks or in mild HIE.
Is therapeutic hypothermia necessary in newborns?
Numerous randomised controlled trials have shown that therapeutic hypothermia reduces death and neurological disability in newborns with moderate and severe hypoxic-ischaemic encephalopathy; for this reason it has become a standard treatment.
Features a therapeutic hypothermia device should have
An ideal hypothermia device should be able to bring the patient to the target temperature quickly, maintain it, usually for 72 hours, and provide slow, controlled rewarming (0.2–0.5 °C per hour). The device should be easy to use, minimise the nurse's need for manual data recording, and help detect side effects such as shivering early.
What is therapeutic hypothermia?
It is a treatment that uses the protective (neuroprotective) effect of cooling the brain tissue by keeping body temperature within a defined range for a defined period. Cooling with a device designed for this purpose is called ‘therapeutic hypothermia’ or ‘active cooling’ in the medical literature; the terms ‘cooling’ and ‘hypothermia’ are both used. If the device automatically adjusts its own setting according to the patient's body temperature, this is called ‘servo-controlled’ cooling.
Mechanism of action of therapeutic hypothermia
Each 1 °C decrease in body temperature reduces brain metabolism by about 6–10%. The effectiveness of hypothermia treatment may vary with the severity of the brain injury and the patient's genetic characteristics. For treatment to be successful, four factors need attention:
Early start: starting treatment as soon as the injury occurs is very important (‘time is brain’).
Duration of cooling: cooling within the same range for a defined period is essential for effectiveness.
Rewarming: rewarming must be slow and gradual.
Prevention and management of side effects.
The Turkish Society of Intensive Care's ‘National Guideline on Targeted Temperature Management after Cardiac Arrest’ (in Turkish) is available at the link below.