WASHINGTON -- Call it brain fog, that loss of memory and thinking ability that strikes tens of thousands of patients after open-heart surgery, and sometimes other big operations, every year.
Now doctors are studying if giving patients certain drugs just before a heart bypass could prevent this mental decline by essentially protecting the patients' brain cells from the rigors of surgery.
The clinical trials mark a turning point: For decades, doctors didn't know what to make of patient complaints that in getting their hearts fixed, something hurt their brains.
Today, few doubt it's a real problem that affects not just heart patients but those undergoing other major surgeries, too, such as hip or knee replacements. Often, patients recover. But one study found 42 percent of heart-bypass patients suffer significant drops in mental sharpness that can last not just months but years. Other research suggests 10 percent of hip-replacement patients suffer similar mental decline.
In some ways this "postoperative cognitive dysfunction" is a byproduct of the modern operating room. As surgery -- particularly the half-million heart bypasses performed every year -- has become increasingly successful, aftershocks such as a muddled brain draw more concern.
"It's a big quality of life issue," said Dr. James Cottrell, president of the American Society of Anesthesiologists.
Variety of suspects
No one knows yet what's to blame. It may be that only certain people are at high risk, such as those whose brain blood vessels are starting to clog and something about surgery speeds up the disease.
For now, suspects range from the heart-lung machine that circulates bypass patients' blood -- it can dislodge tiny bits of fat, blood clots or air bubbles that flow to the brain -- to the inflammation and post-surgery fever that are a risk after any major operation.
Surgery's stresses spark inflammation and other reactions that "in some ways is the body's way of healing itself," explains Dr. Mark Newman, anesthesiology chairman at Duke University and a leading expert on post-surgery mental decline. "But the question is if it goes beyond a certain level, do you end up with problems?"
Newman and other scientists are studying if injecting patients with one of three different medications before a bypass could block that chain reaction and spare brain cells.