Doctors debate effectiveness of mercury-free blood pressure cuffs

WASHINGTON (AP) _ There's a quiet revolution taking place in hospitals and doctors' offices: More and more are getting rid of blood-pressure cuffs that for a century have been the standard, in

Tuesday, December 31st 2002, 12:00 am

By: News On 6

WASHINGTON (AP) _ There's a quiet revolution taking place in hospitals and doctors' offices: More and more are getting rid of blood-pressure cuffs that for a century have been the standard, in favor of newer models that don't contain the environmental pollutant mercury.

But these new devices may not be as reliable, some specialists say, and even a small discrepancy could cause mistaken diagnoses that could harm thousands of people.

They want hospitals to hold off replacing all their mercury-containing cuffs until such concerns are settled.

``What we're cautioning against is not overreacting to the environmental concerns and giving up accuracy,'' says Dr. Daniel W. Jones of the American Heart Association, which is pushing for quick research. ``We just don't know how good many of the replacements are.''

On the other side are about two dozen hospitals that have replaced mercury-containing cuffs as part of a broader government-industry effort to virtually eliminate mercury in hospital waste by 2005.

Led by the Mayo Clinic, proponents of the new models say they can work just as well as the old ones _ if they are tested every few months to make sure they're not wearing out.

The new gauges have more parts than the mercury version, ``so they are subject to more wear and tear,'' says Dr. Vincent Canzanello. His three-year study of Mayo's new type, called aneroid cuffs, found only a 1 percent failure rate, thanks to good maintenance.

Any hospital can run the maintenance checks, says Canzanello, who is working with the National Institutes of Health to post Mayo's cuff-testing program on the Internet so other hospitals can copy it.

It's unclear how many doctors even know maintenance is necessary, much less perform it.

Dr. Clarence Grim of the Medical College of Wisconsin surveyed Green Bay doctors who were using aneroid cuffs and found one-third were reading blood pressure too low, by an average of 6 points. In the worst case, one of an obstetrician's aneroid cuffs was 30 points off.

``There's no law that says you have to inspect your blood-pressure device every six months,'' says Grim, who'd like to see such a rule. ``That just leaves the public open to severe problems because of bad blood-pressure measurement.''

It's a balancing act for health workers across the country, who check blood pressure 1 million times a day.

``We can't just be interested in blood pressure and stick our head in the sand and pollute the environment,'' says Dr. Ed Roccella of the NIH, which has replaced most of its mercury gauges.

Still, Roccella keeps a mercury cuff in his own office, one of several that NIH doctors can use for maintenance checks of their newer models.

And the doctors' debate draws attention to a bigger issue: Harried health workers frequently measure blood pressure incorrectly regardless of which machine they use.

Anything from a patient's legs swinging off the exam table _ feet should be flat on the floor _ to a too-fast check can throw off the results. Grim and Roccella advise people to ask for another check if the first one seems wrong.

One in five Americans has high blood pressure, a chief contributor to heart disease, kidney disease and other ailments. To measure blood pressure, a cuff is inflated to stop blood flow in the arm's main artery temporarily.

When the cuff is deflated, pressure from the resuming blood flow is measured by one of the following:

_A mercury-containing gauge.

_A gauge containing a metal, spring-like device instead of mercury. The most popular alternative to mercury, the aneroid devices are considered highly accurate if properly maintained.

_An automated device using electronic waves to calculate the pressure. They're not reliable in patients with irregular heartbeats or stiff arteries, Roccella cautions. But those made to national manufacturing standards are useful when patients need continual monitoring, such as in intensive care, or for easy at-home use.

Grim said not all such devices are made to those standards. Even critics say blood-pressure cuffs are a tiny contributor to mercury pollution. Hospitals use many mercury-containing devices, including batteries, light bulbs and feeding tubes. Also, on the rare occasions a blood-pressure cuff breaks, the spilled mercury is supposed to be recycled.

But that's expensive _ Mayo spent $26,000 on spills in two years _ and there's no guarantee some mercury won't wind up in the trash and leach into the environment.

Still, the heart association advises hospitals to keep a few mercury cuffs on hand until it can determine the best alternative.