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Lowering Blood Pressure Harms Stroke Victims

10/27/2003      

MONDAY, Oct. 27 (HealthDayNews) -- Lowering a patient's blood pressure in the first 24 hours after a stroke increases long-term brain damage, a Brazilian study finds.

It is one of the first scientifically controlled studies about a critical phase of treatment in which guidelines are few and murky, American neurologists say.

"The current literature does not include a gold standard based on a randomized clinical trial," says Dr. Karen C. Johnston, an associate professor of neurology and health evaluation sciences at the University of Virginia Health System. "All we have is a number of anecdotal reports and uncontrolled studies, which more and more are suggesting that lowering blood pressure would be harmful."

Johnston is co-author of an editorial accompanying the report on the Brazilian study in the Oct. 28 issue of Neurology.

"It has been common for general practitioners to try to reduce blood pressure in the acute stage of a stroke, although this is not a recommendation of the American Academy of Neurology," says study author Dr. Jamary Oliveira-Filho, a professor of neuroanatomy at the Federal University of Bahia.

That practice is based on a more or less instinctive feeling that lowering blood pressure has to be good, since high blood pressure is a major risk factor for stroke, Oliveira-Filho says. But there have been almost no studies about the effect of the practice on patients.

In an effort to fill the gap, Oliveira-Filho and his colleagues made careful measurements of blood pressure of 115 stroke patients admitted to the Hospital San Rafael in Salvador, Brazil, between January 2001 and October 2002.

The average blood pressure of those patients when they arrived at the hospital was 160 over 94. Pressure dropped in every patient in the first 24 hours, either spontaneously or because they were given drugs.

An assessment three months later found that the risk of a poor outcome, meaning that the patients were more likely to need help in everyday activities, was almost doubled with every 10 percent decrease in blood pressure in the 24-hour period, the researchers report.

In those few hours, Oliveira-Filho says, high blood pressure is good because it increases blood flow to the brain, reducing the amount of tissue killed by a stroke. After that acute phase, the need to get blood pressure down to healthy levels returns.

The study is "one more piece of information needed to help us figure out how to manage blood pressure in the hours after a stroke," Johnston says. "There still are a number of clinicians who are not clear on how best to manage blood pressure in an acute setting."

The Brazilian study will not resolve the issue, she says. What is needed is "a definitive randomized trial." Until one is done, Johnston says, "based on the limited information we have, aggressive blood pressure reduction in the acute setting should probably be avoided. But based on the information we have, the time frame for the acute phase is not known."

Quick treatment of a stroke is needed to limit the damage it does, but an American survey finds that fewer than 20 percent of adults know all the signs of a stroke.

A telephone survey of 61,019 adults finds that most know that confusion, numbness, and dizziness are signs of a stroke, but only a few listed trouble seeing and a severe, unexplained headache as a stroke symptom, says a report by physicians at the U.S. Centers for Disease Control and Prevention. More than a third incorrectly listed severe chest pain as a stroke symptom.

However, 86 percent of those questioned knew the right thing to do when a stroke is suspected: Call 911 for emergency medical help.

More information

A complete list of stroke signs and symptoms can be found at the American Heart Association or the National Institute of Neurological Disorders and Stroke.

SOURCES: Jamary Oliveira-Filho, M.D., Ph.D., professor, neuroanatomy, Federal University of Bahia, Salvador, Brazil; Karen C. Johnston, M.D., associate professor, neurology and health evaluation sciences, University of Virginia Health System, Charlottesville; Oct. 28, 2003, Neurology

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