Researchers at Johns Hopkins School of Medicine in Baltimore assessed 15 patients, age 57 to 81, who underwent coronary artery bypass graft surgery and were believed to be at high risk for postoperative stroke.
All 15 patients took the Mini-Mental Status Examination before surgery, which measures thinking, learning, and memory. Their mean arterial blood pressure, or MAP, which estimates the pressure of the blood that perfuses the organs of the body, was taken before and during surgery. Thirteen patients also underwent postoperative magnetic resonance imaging of their brains.
The researchers found that patients whose MAP decreased by 27 millimeters or mercury or more during surgery scored significantly lower on the Mini-Mental Status Examination after surgery.
The team also found that six of the 13 people who underwent MRIs had evidence of acute strokes, and those who had the 27-plus millimeter drop in MAP were 2.7 times as likely to have such a lesion as those whose MAP decreased by a smaller amount.
The researchers said the cognitive declines they noted might be partially due to the strokes, and proposed further studies to define the relationship between operative MAP drop, stroke and poorer short-term postoperative cognitive performance.
A report on the research appears in the early online edition of the August issue of Archives of Neurology.