Effects of Surface Cooling On Stroke Outcome triaL (COOL) (COOL)

Several studies have identified fever as an independent predictor of poor outcome in patients with acute stroke. Experimental data and clinical studies indicate that therapeutic hypothermia has neuroprotective effects associated with better clinical outcome, probably through reduction of infarct volume and cerebral edema in patients with ischemic and hemorrhagic stroke, respectively. It is to be expected that the beneficiary effects of hypothermia will be more pronounced if initiated early after stroke onset, which underlines the rational that this technique ideally should be initiated in the prehospital phase of acute stroke management.

Therapeutic hypothermia can be obtained by external or by endovascular cooling. Most methods aim to lower the body temperature to <33°C and therefore require patient sedation and intubation. In contrast to patients with cardiac arrest, sedation and intubation preferably are avoided and profound cooling of the entire body is not desired nor required in in stroke patients. EMCOOLS pads® have originally been developed by EMCOOLS Medical Cooling Systems AG (Austria) for profound external cooling of patients with cardiac arrest. The novel EMCOOLS Brain.Pad® was redesigned to mildly lower the brain temperature through noninvasive surface cooling of the cerebropetal arteries at the cervical level. Pilot studies in healthy volunteers demonstrated that a decrease of 0.5-1°C (tympanic measurement) can be safely obtained by application of EMCOOLS Brain.Pad® during 60 to 90 minutes. No relevant side effects were observed in these small studies, but possible effects on cerebrovascular blood flow were not evaluated.

Early application of mild therapeutic hypothermia in acute stroke patients builds further on their research group's experience with hypothermia in animal models and stroke patients. The investigators propose a prospective clinical trial comparing current clinical practice with the induction of mild hypothermia using EMCOOLS Brain.Pads® in patients presenting with acute stroke. If safety, feasibility, patient acceptance and efficacy are confirmed in the inhospital setting, the next step will involve evaluation of this approach in prehospital acute stroke care.