FRIDAY, Feb. 17, 2006 (HealthDay News) -- When someone suffers a stroke, time is of the essence: There's only about a three-hour window to administer the most effective drug treatment.
But now, an analysis of previous research provides more evidence that paramedics and doctors can stop the clock -- at least temporarily -- with heavy doses of oxygen.
"It [the initial finding] still holds up," said study senior author Dr. Aneesh Singhal, an assistant professor of neurology at Harvard Medical School. "And theoretically, the risks are very minimal as compared to the potential benefit."
Strokes occur when blood flow through the brain is disrupted. About 700,000 Americans have strokes each year, and nearly 157,000 die, according to the American Stroke Association.
Over the past decade, doctors have made major strides in stroke care, thanks to a drug treatment called tissue plasminogen activator, or tPA. If given within three hours of a stroke, the drug can break up clots that prevent proper blood flow.
But it's not always possible to get a stroke victim to a hospital and run the appropriate tests in time for that deadline.
Enter oxygen treatment, which could provide enough valuable oxygen to the brain to keep conditions stable for a while.
One idea was to put stroke patients in hyperbaric chambers, which force oxygen into the body through high pressure; the chambers are perhaps best known for their use as a treatment for scuba divers struggling with the bends. But the hyperbaric approach didn't work in stroke patients, Singhal said.
So, he and other researchers tried a different approach, using simple facemasks to deliver heavy doses of oxygen. They used MRI brain scans to track 19 stroke patients, 11 of whom received special treatment with oxygen and eight who only breathed room air.
The researchers found that oxygen treatment appeared to significantly reduce damage from stroke both four hours and 24 hours after an attack.
The findings were first reported in the journal Stroke in October 2005. Singhal and his colleagues re-examined the existing research using a different statistical analysis and released their latest findings Friday at the American Stroke Association's annual conference, in Kissimmee, Fla.
Their conclusion: Even when viewed in a different light, the oxygen treatment seems to work.
Oxygen therapy for stroke patients might serve to protect them as they wait for full treatment in a hospital, Singhal said. And since the treatment is simple, paramedics could administer it in an ambulance.
Why does oxygen work? Singhal said researchers aren't sure about the exact process, but it likely has something to do with bringing oxygen to brain tissues that aren't getting enough of it because of disruption in blood flow.
Dr. Argye Hillis, associate professor of neurology at Johns Hopkins University, said the findings are promising, although the number of participants was small.
"It certainly is a cheap intervention," Hillis said, adding that there's "very little risk" from getting oxygen for a short period of time.
If further research confirms that the treatment works, there could be major benefits by extending the time window for treating stroke, she said. "If we could extend the time window to four hours instead of three hours, we might be able to treat a lot more patients."
More information
Learn more about stroke from the American Stroke Association.
