Cardio Monitoring Device Falls Out Of Favor

Main Category: Medical Devices
Also Included In: Cardiovascular / Cardiology
Article Date: 31 Jul 2007 - 1:00 PDT

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The pulmonary artery catheter, a once-lauded cardiac monitoring device, appears to be fading into medical history, a study finds.

Use of the device -- a thin tube inserted into a lung artery to get information about a patent's condition -- decreased by 68 percent in the United States between 1993 and 2004, according to a report in the July 25 issue of the Journal of the American Medical Association

The reason behind the drop in the device's popularity: "Multiple studies have shown that it doesn't help," according to lead researcher Dr. Renda Soylemez Wiener, an assistant professor of medicine at Dartmouth Medical School and a physician at the Department of Veterans Affairs Medical Center in White River Junction, Vt.

The procedure was first introduced in 1970, and "studies done in the 1980s estimated that 20 to 40 percent of critically injured patients were getting it," Wiener said.

The pulmonary artery catheter provided information on cardiac output and pressure in the small blood vessels of the lung -- apparently important measures of how well the heart was pumping blood.

However, doubts on the value of that information began to surface over the last few decades. One study conducted in 1996 suggested that use of the pulmonary artery catheter actually increased cardiovascular risk for some patients. Then, several major studies found that the device did not increase the patient's risk, but it did not improve their outcome, either.

Doctors seem to have gotten the message, Wiener said. Data from the National Inpatient Sample, a U.S.-wide source of hospital information, found that use of the pulmonary artery catheter "has gone down dramatically, universally," Wiener said, from 5.66 per 1,000 medical admissions in 1993 to 1.99 in 2004. The drop in usage was steepest for patients diagnosed with a heart attack, at 81 percent.

"This may well reflect the end of the story on this monitoring device," said Dr. Gordon D. Rubenfeld, who co-authored an accompanying editorial written while he was at the University of Washington in Seattle. He now is professor of medicine at the University of Toronto.

Doctors' early enthusiasm for the device is easy to understand, Rubenfeld said. "It made us feel good, because it made us feel better," he said. "It gave us information [about the patient], and information is power."

That enthusiasm persisted, because "it is very hard to prove that monitoring and measuring devices are helpful, because the benefits are small," Rubenfeld said. "It was only in the last few years that well-designed trials showed it to be of no demonstrable value in patients."

The catheter probably will continue to be used, at least on a limited basis, because some physicians have become accustomed to its use, and others find it helpful for certain groups of patients, he said. But that use should be monitored carefully, "because these are complicated devices that require training and skill to set up, not only by doctors, but also by nurses," Rubenfeld said.

Aside from the risks of such limited use, the rise of alternative monitoring devices using less invasive technologies such as ultrasound has contributed to the decline of the pulmonary artery catheter, Rubenfeld said.

The study should also have a wider lesson for doctors, he said.

"The clinician really should be a little skeptical about all these devices," Rubenfeld said.

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