FRIDAY, July 29 (HealthDay News) -- Low blood pressure while undergoing dialysis puts patients at increased risk for clots where their blood vessels are connected to the dialysis machine, a new study says.

Previous research had found that a sudden drop in blood pressure during dialysis can lead to short-term gastrointestinal, muscular and neurologic symptoms, and long-term problems such as stroke, seizure, heart damage and death.

This new study, led by researchers at Stanford University School of Medicine, examined data collected between 1995 and 2000 from 1,426 dialysis patients who took part in a clinical trial sponsored by the U.S. National Institutes of Health.

Dialysis is a treatment for kidney-failure patients that uses a machine to cleanse their blood. Many patients are attached to the dialysis machine through a fistula, a surgically created vascular access point in the body that's connected to the tubes that take and return blood to the dialysis machine.

The analysis revealed that patients who experienced low blood pressure most often while undergoing dialysis were two times more likely to have a clotted fistula than those who had the fewest episodes of low blood pressure.

"Our analysis shows another adverse consequence associated with a fall in blood pressure during dialysis for patients," lead author and nephrologist Dr. Tara Chang said in a Stanford news release. "Vascular access is their lifeline. It's required for dialysis and without dialysis, they'll die."

Because low blood pressure occurs in about one-quarter of dialysis sessions, "physicians already try to avoid low blood pressure during dialysis through various means," Chang said. "This is just one more good reason to continue these efforts."

The study is published in the July 29 online edition of the Journal of the American Society of Nephrology.

More information

The National Kidney Foundation has more about dialysis.