From the Guidelines
Hypothermia for 24 hours or more is recommended.
Rationale
- The optimal duration for mild induced hypothermia and TTM is unknown, but it is currently most commonly used for 24 h 1.
- Two observational trials found no difference in mortality or poor neurological outcome with 24 h compared with 72 h of hypothermia 1.
- The American Heart Association guidelines suggest that TTM be maintained for at least 24 hours after achieving target temperature (Class IIa, LOE C-EO) 1.
- The European Resuscitation Council and European Society of Intensive Care Medicine guidelines recommend maintaining a constant, target temperature between 32 and 36 °C for those patients in whom temperature control is used (strong recommendation, moderate-quality evidence) 1.
Key Points
- Target temperature range: 32-36 °C
- Duration: at least 24 hours
- Temperature control methods: feedback-controlled endovascular catheters, surface cooling devices, cooling blankets, and frequent application of ice bags
- Monitoring: core temperature using an esophageal thermometer, bladder catheter, or pulmonary artery catheter
- The optimal duration and target temperature may vary depending on the patient's condition and response to treatment, and further research is needed to determine the best approach 1.
From the Research
Hypothermia Duration
The duration of hypothermia can vary depending on the specific medical condition being treated.
- Therapeutic hypothermia is typically defined as a core body temperature of 32°C-35°C for a period of 24-48 hours 2.
- However, some studies have investigated the use of prolonged hypothermia, lasting from 48 hours to 14 days, for certain conditions such as traumatic brain injury and nontraumatic brain injury 3.
- In some cases, hypothermia may be continued for an extended period, such as 14 days, to control refractory intracranial hypertension and global cerebral edema 3.
- The feasibility and safety of waking cardiac arrest patients receiving mild therapeutic hypothermia after 12 hours to enable early neuro-prognostication has also been investigated, with hypothermia continued for 24 hours and fever prevention for 72 hours 4.
Specific Conditions
The use of hypothermia for specific conditions, such as cardiac arrest, has been studied extensively.
- For out-of-hospital cardiac arrest, hypothermia at 32-34°C for 12-24 hours has been recommended to mitigate brain injury and increase survival 5.
- However, recent systematic reviews suggest that there may be little or no effect of delivering hypothermia on mortality, and the current recommendation is to treat fever and keep body temperature below 37.5°C 5.
- Accidental hypothermia can also be treated with hypothermia, and a case report has demonstrated the importance of effective cardiopulmonary resuscitation and extracorporeal circulation for rewarming in a patient who survived two hours of ventricular fibrillation in accidental hypothermia 6.