**5. MI**

4 Therapeutic Hypothermia in Brain Injury

Despite advances in ICU care, cardiac arrest remains a significant cause of death in many countries. Mortality reports vary from 65 to 95% for out-of hospital cardiac arrest. I is a class –I recommendation now that after return of spontaneous circulation in out-of-hospital VF cardiac arrest , patients that remain comatose should be subjected to hypothermia at 32°C to 34°C for 12 to 24 hours. This may also be applied to comatose adult patients with spontaneous circulation after OHCA from a non VF rhythm or in-hospital cardiac arrest.1

Several unanswered questions however remain, due to lack of randomized studies. These in part, relate to time from initiation of therapy to achieving target temperature, and whether this is a significant predictor of outcome. The optimal rate of cooling is also an unanswered question, so is the optimal duration of TH in some settings, albeit in the setting of cardiac arrest, improved outcomes have been demonstrated with 12 and 24 hrs of TH at 32°C to 34°C. Hypothermia for neonatal asphyxia is commonly performed for 72 hrs, while hypothermia for cerebral edema associated with liver failure has been reported for as long

Traumatic brain injury (TBI) is a leading cause of death and disability in young people in Western countries. The neuroprotectant effects are thought to be related to decreased metabolic rate, cerebral blood flow, decreased release of excitatory neurotransmitters,

While studies have shown that Hypothermia is clearly effective in controlling intracranial hypertension (level of evidence: class I); it has been difficult to show that lowering ICP definitely improves outcomes. Few positive studies with regard to survival and improved neurological outcome have been shown mainly in tertiary referral centers with experience in use of hypothermia. Here again, as in cardiac arrest, more unanswered questions remainduration, time of cooling and rewarming, type of rewarming. Currently, most centers perform it for at least 48 hours. Rewarming is typically done slowly, over at least 24 h (level of evidence: class IIa). 4 If there is evidence of ICP elevation during rewarming, again no definite recommendations are available, but most experts will proceed with repeat cooling. It could be that in traumatic brain injury, other therapies, including cerebrospinal fluid drainage, osmolar therapies, sedation, barbiturate coma, and decompressive craniectomy may confer additional benefits that may make it more difficult to prove that Therapeutic

Similar to Cardiac arrest and TBI there is evidence from animal studies that show benefits of therapeutic hypothermia in stroke. Use of hypothermia in stroke remains experimental, until large prospective randomized human clinical trials using hypothermia in acute stroke

decreased apoptosis, cerebral edema, decreased cytokine response etc.3

**2. Cardiac arrest** 

as 5 days. 2

**3. TBI** 

hypothermia is superior.

**4. Stroke** 

are completed. 5

Hypothermia may decrease infarct size in patients with acute myocardial infarction after emergency percutaneous coronary intervention
