News Release

“COOL AID” safe after stroke, may deter side effect of clot-busters

Peer-Reviewed Publication

American Heart Association

DALLAS, August 3 – Cooling the brain after an ischemic stroke may limit both initial tissue damage caused by a stroke as well as subsequent damage resulting from the restoration of blood flow after using clot-busting drugs, according to a report in the August issue of Stroke: Journal of the American Heart Association.

“The irony is that while restoration of blood flow is a prerequisite for recovery, sometimes this restoration, if it occurs into already damaged tissue, can paradoxically make things worse and thereby antagonize the benefit that the patient may have otherwise enjoyed,” says Michael A. De Georgia, M.D., co-principal investigator and head of the Neurological Intensive Care Program at The Cleveland Clinic Foundation.

De Georgia and colleagues found that inducing moderate hypothermia after a stroke is feasible and safe. Preliminary results of this study, which researchers call “COOL AID” (COOLing for Acute Ischemic Brain Damage) were presented at the American Stroke Association’s 26th International Stroke Conference in February.

Some individuals are severely disabled by strokes partly because they have irreversibly damaged brain tissue by the time they arrive at the hospital. Clot-busting drugs can restore blood flow and limit tissue damage if delivered within three hours of stroke symptom onset. Yet, sometimes restoring blood flow causes more tissue damage known as reperfusion injury. This injury occurs when the rush of restored blood flow causes more insult to already injured tissue. Some experiments have indicated that hypothermia (lowered body temperature) can suppress the release of oxygen free radicals and inflammatory responses known to play a role in reperfusion injury.

The goal of this pilot study was to provide brain protection to patients at high risk of developing large strokes by combining strategies to restore blood flow with hypothermia. After clot-busting drugs showed little or no improvement, researchers induced surface cooling in patients with severe ischemic strokes (caused by a blood clot) affecting the middle cerebral artery (MCA) territory. Individuals with strokes affecting the MCA region usually have severe paralysis on one side of their body.

Individuals with MCA territory stroke who arrived within six hours of symptom onset were screened for the study. Hypothermia was initiated with cooling blankets and ice water/alcohol baths. To prevent shivering, the patients received drugs to paralyze them, were sedated, and had breathing tubes inserted.

It took an average of three and half hours to achieve hypothermia, which was then maintained at a core temperature of 32 degrees Celsius (89.6 degrees Fahrenheit) for 12 to 72 hours. Ten patients who received hypothermia were compared with nine similar patients who were kept at a normal temperature. All were monitored closely for complications.

“Hypothermia was well tolerated by most patients and there were no significant differences in minor or critical complication rates between the two groups,” notes Derk Krieger, M.D., co-principal investigator of the study.

Four cooled patients had critical complications including atrial fibrillation, slowed heart rate and hemorrhage; and two among the non-cooled group experienced critical complications such as hemorrhage, pneumonia and sepsis (blood poisoning).

Death rates were also comparable at three months: three of the 10 (30 percent) hypothermia patients died compared with two of nine (22 percent) of nonhypothermia patients.

On a scale that measures the range of disability, scores were better in cooled patients at three months but not statistically significant. The scale sets normal function at 0 and death at 6. The average score cooled patients was 3.1 compared with an average score of 4.2 in the non-cooled group.

The authors say refinement of the cooling process, optimal target temperature, duration of therapy and clinical efficacy requires further study.

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Other authors of the study were Alex Abou-Chebl, M.D., John C. Andrefsky, M.D., Cathy Sila, M.D., Irene L. Katzan, M.D., Marc. R. Mayberg, M.D., and Anthony Furlan, M.D.

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