Occurring in only 0.1 percent to 3 percent of all noncardiac surgeries, the risk for stroke development following surgery remains a complication of concern for patients. New research reveals that patients who experience lower blood pressure during noncardiac surgery may face an increased risk of developing a stroke post-surgery.

Researchers from University Medical Center Utrecht, Netherlands, investigated the possible role of various levels of blood pressure during surgery in the occurrence of stroke after surgery. Stroke following surgery is most often an ischemic stroke or embolic stroke due to the release of particles during surgery obstructing a blood vessel to the brain.

"The investigation focused on patients in procedures other than cardiac, neurological or carotid surgeries, which already carry a known increased risk for post-surgical stroke development," said Cor J. Kalkman, M.D., Ph.D., University Medical Center Utrecht, Netherlands.

The study included over 30,000 patients undergoing surgery from January 2002 to March 2008. 41 patients who experienced a stroke within 10 days after surgery were selected and matched with 164 control patients who did not experience a stroke.

After adjustment for known stroke risk factors of age, gender, history of diabetes, hypertension and previous stroke, researchers found a trend toward a higher risk for stroke after surgery for patients who experienced lower blood pressure levels during surgery.

"While these findings are of clinical importance because blood pressure is a controllable factor, the results should be interpreted with extreme caution due to the small numbers of stroke patients and the complex interaction of patient and surgical factors on the risk of stroke following surgery," said Dr. Kalkman. "Especially for sick or elderly patients who may be less tolerant to low blood pressure levels the results indicate that tight blood pressure control and monitoring may be the next step to prevent excess strokes."

For all groups of patients, a history of previous stroke remains the main risk factor for developing a stroke after surgery.

About Stroke

• Ischemic stroke
• Hemorrhagic stroke

• A clot that stays in place in the brain is called a cerebral thrombus.
• A clot that breaks loose and moves through the bloodstream to the brain is called a cerebral embolism.

Another important cause of cerebral embolisms is a type of arrhythmia called atrial fibrillation. Other causes of ischemic stroke include endocarditis, an abnormal heart valve, and having a mechanical heart valve. A clot can form on a heart valve, break off, and travel to the brain. For this reason, those with mechanical or abnormal heart valves often must take blood thinners.

A second major cause of stroke is bleeding in the brain hemorrhagic stroke. This can occur when small blood vessels in the brain become weak and burst. Some people have defects in the blood vessels of the brain that make this more likely. The flow of blood after the blood vessel ruptures damages brain cells.

• High blood pressure is the number one reason that you might have a stroke. The risk of stroke is also increased by age, family history of stroke, smoking, diabetes, high cholesterol, and heart disease.
• Certain medications increase the chances of clot formation, and therefore your chances for a stroke. Birth control pills can cause blood clots, especially in woman who smoke and who are older than 35.
• Men have more strokes than women. But, women have a risk of stroke during pregnancy and the weeks immediately after pregnancy.
• Cocaine use, alcohol abuse, head injury, and bleeding disorders increase the risk of bleeding into the brain.
  

About the American Society of Anesthesiologists

Physicians providing the lifeline of modern medicine. Founded in 1905, the American Society of Anesthesiologists is an educational, research and scientific association with 43,000 members organized to raise and maintain the standards of the medical practice of anesthesiology and improve the care of the patient. For more information visit the American Society of Anesthesiologists Web site at http://www.asahq.org.