Pulse pressure linked to dialysis death rate. (Biomedicine).

A high reading for pulse pressure--the difference between the two numbers in a blood pressure reading--may increase risks for people on kidney dialysis, according to a new analysis of clinical records.

The average pulse pressure is usually below 50 millimeters of mercury, but in dialysis patients it is often much higher, says Preston Klassen, a physician at Duke University Medical Center in Durham, N.C. An analysis of medical data for more than 37,000 dialysis patients around the United States revealed that 90 percent of them exceed a pulse pressure score of 50. Every additional 10 points of pulse pressure boosted by roughly 12 percent a patient's risk of dying at any given time during the 1-year study, the team reports in the March 27 Journal of the American Medical Association.

A high reading suggests that a patient has stiff, inflexible arteries, Klassen says. When this is the case, blood pumped out of the heart slams into much smaller arteries and capillaries. It creates a ripple-like pressure wave back toward the heart, even before the main contraction is finished. This requires the heart to work harder and limits the amount of blood that can flow into the heart muscle itself via the coronary arteries, Klassen says.

Although high blood pressure is a well-known risk factor for dialysis patients, these findings suggest that physicians should also pay attention to pulse pressure. Among dialysis patients, heart problems constitute the most common cause of death. Since researchers don't fully understand pulse pressure, the best current therapy is the old standard--keeping high blood pressure in check--Klassen says.--N.S.