MedPage today’s Michael Smith reports that the evidence is showing that “inducing mild hypothermia – to between 32 and 35° C — can prevent or reduce permanent injury after certain types of neurological insult. Dr. Polderman shares that while this technique has been shown effective for post-ischemic injury after global anoxia and for lowering of intracranial pressure it still needs to be rigorously tested for traumatic brain injury, ischemic stroke, and thoracoabdominal aneurysm repair. Smith reports:
“Available evidence suggests that hypothermia will be more effective if it is applied soon after an injury, implying that, in the future, treatments would begin in the ambulance or emergency room,” he said.
Among the potential indications Dr. Polderman spelled out:
- Cardiac arrest and cardiopulmonary resuscitation, where the evidence is good that cooling the body to about 33° C improves the odds of a good neurological outcome. The number needed to treat is about six.
- Perinatal asphyxia, where hypothermia should “be strongly considered.” Side-effects seen in clinical trials seem to be minor and the number needed to treat is six.
- Reducing intracranial pressure in patients with cerebral edema, regardless of the cause. Several clinical trials have shown that hypothermia reduces pressure, although the reduction does not necessarily lead to improved outcome.
Evidence in traumatic brain injury is mixed, Dr. Polderman said, although he said it’s clear that cooling can be effective in cases of severe traumatic brain injury and intracranial hypertension provided that treatment starts early, continues for between two and five days, and is followed by a slow rewarming over at least 24 hours.