Volume 12, Number 16 April 15, 2005

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Cooling collar shows promise for treating stroke victims

By Michael Robin

Research Communications

College of Medicine stroke researchers Viv Ramsden and Jim Thornhill are working to buy time for patients suspected of suffering a stroke with new tools to use in the critical minutes before the patient can get to the hospital.

Their invention consists of a precision body temperature monitoring system and a “cooling arch”. This C-shaped collar fits around a patient’s neck from the back and applies cooling to the carotid arteries that feed blood to the brain.

Viv Ramsden and Jim Thornhill

Viv Ramsden and Jim Thornhill

Photo by Michael Robin

Animal models used by fellow stroke researcher and collaborator Dale Corbett of Memorial University in Newfoundland confirm that such cooling not only reduces initial damage, but also the secondary harm caused when injured and dying cells cause surrounding tissue to die. This destruction can be more extensive than the initial stroke.

“He and many others have shown that with decreases in core temperature in animals, not only could you demonstrate acute protection but long-term protection,” Thornhill says, “even months and years after the event, such that these animals behave normally. That has been probably the most important breakthrough with cooling.”

But there are challenges with using cooling on patients with suspected stroke before they get to the hospital. Existing technologies like cooling blankets can quickly set off the body’s reflexes to cold, causing shivering which can counteract the cooling effect. Plus, if the blood is cooled too much, it becomes prone to clotting – the last thing a stroke patient needs.

Based on existing literature, Ramsden and Thornhill propose that a one- to two-degree reduction in body temperature will minimize risk to the patient. This calls for a level of precision in monitoring body temperature never before accomplished in the pre-hospital setting. Just like blood pressure and heart rate, temperature in a healthy person fluctuates throughout the day. Their level of activity, eating, even drinking a cup of coffee affects body temperature.

“It’s not cooling very much – we don’t want to go more than one or two degrees below their baseline temperature, whatever that happens to be,” Ramsden says.

Therein lies the challenge. Measurement of most vital signs, such as blood pressure, has advanced over the last 50 years. This is not so with temperature. The 37 degrees Celsius “normal” number used today was developed from averages rather than any given individual. Complicating this, women’s baseline temperatures are generally lower, except during ovulation, and a large percentage of patients with suspected stroke in the pre-hospital setting are elderly women.

“We’re interested in knowing what the baseline of each patient is and focusing on maintaining or slightly reducing that baseline temperature,” Ramsden says. “Currently, we don’t have any tools that work well in the pre-hospital care setting to monitor these temperatures appropriately, so we see this as a big opportunity.”

The stroke treatment invention is now in the prototype stage. Ramsden and Thornhill are the first recipients of a new prototype development fund established by the U of S Industry Liaison Office (ILO). The fund is aimed at helping researchers get their ideas ready for outside investment and commercialization.

“University research is typically curiosity-driven, so many of the inventions brought to us are very early-stage,” says ILO Director Doug Gill. “When we’re talking to licensees, they see a list of unanswered questions, risk, and expense. We answer some critical questions and remove some of these risks to make the inventions more attractive.”

Both the Canadian Institutes of Health Research (CIHR) and the Natural Sciences and Engineering Research Council (NSERC) have technology development programs, but technologies must be brought to a certain stage to qualify. Ramsden and Thornhill hope to take advantage of CIHR’s Proof of Principle (POP) program.

“Typically, our inventions need a little more work to qualify,” Gill says.

Candidates for the ILO’s prototype development fund are invited to apply by ILO’s technology development managers. Grants are for no more than one year, and up to $25,000 in value.

For more information, contact communications.office@usask.ca

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