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Problems reported with two heart rescues.

Problems reported with two hear rescues

Cardiopulmonary resuscitation (CPR), a standard emergency treatment for sudden heart failure, appears futile in many elderly people, according to a new study. Reviewing medical charts of 503 elderly patients resuscitated after cardiac arrest, researchers found that only 3.8 percent left the hospital alive. In previous studies including both young and old patients, about 15 percent survived to leave the hospital.

Donald J. Murphy of the George Washington University Medical Center in Washington, D.C., and his colleagues identified several factors affecting post-CPR survival among patients aged 70 and older. Resuscitated patients who were alone when their hearts stopped fared worst, with fewer than 1 percent surviving long enough to leave the hospital. But even among those attended by hospital personnel when the arrest occurred, only 10 percent survived.

Murphy notes that serious illnesses or certain abnormal heart rhythms can lead to cardiac arrest, and while medics can restart the heart, they can't reverse the course of the disease. He details his group's results in the Aug. 1 ANNALS OF INTERNAL MEDICINE.

In an accompanying editorial, Philip J. Podrid of the Boston University School of Medicine calls the study's results "depressing." However, he told SCIENCE NEWS, "I don't think it calls into question the value of CPR. I think it calls into question the value of resuscitation of elderly patients who have chronic diseases."

Physicians attending the elderly generally agree they should discuss CPR survival statistics and "do-not-resuscitate" orders with virtually every aged patient entering a hospital or nursing home. Murphy, however, located evidence of such discussions in only 21 of the 503 charts reviewed.

"You look at CPR attempts on TV and it looks like a pretty benign procedure that works most of the time," Murphy says. "That's not the case at all."

CPR is not the only cardiac emergency procedure receiving scrutiny in recent weeks. For decades, scientists have injected solutions of sodium bicarbonate (baking soda) into the blood of cardiac arrest patients to correct excess acidity, or acidosis. But some research in animals has suggested it may do just the opposite. Now, in the July AMERICAN JOURNAL OF MEDICINE, researchers report the first controlled study showing that bicarbonate can have similar harmful effects in humans.

Studies in dogs demonstrate that when insufficient oxygen is available to tissues, bicarbonate increases rather than decreases acidosis (SN: 5/18/85, p.311). Normally, when muscles can't get enough oxygen, they make lactic acid, causing acidosis. A healthy heart can handle the situation, but a diseased heart provides tissues with only the bare minimum of oxygen. A vicious circle ensues. Without enough oxygen, the liver -- which normally removes lactic acid -- can't do its job. Starved for oxygen, the heart's efficiency plummets.

Bicarbonate breaks down in the blood, releasing carbon dioxide, which can increase acidosis in cells. It may also reduce oxygen availability by binding the gas more closely to hemoglobin in red blood cells.

Bicarbonate appears to cause the same problems in people with congestive heart failure, a condition study coauthor Allen I. Arieff calls "just shy of cardiac arrest." He and his colleagues at the University of California, San Francisco, injected either saline or bicarbonate solution into patients undergoing evaluation for congestive heartfailure. "These human studies completely support the animal work," Arieff says. "If there is any problem with oxygen getting to the tissues, bicarbonate does exactly the opposite of what you'd like it do to." In contrast, he notes, it safely relieves acidosis in patients without heart disease.

In 1986, prompted by the animal studies and a lack of clear evidence showing bicarbonate's benefits in cardiac arrest, the American Heart Association (AHA) recommended limiting its use. According to Joseph P. Ornato of the Medical College of Virginia in Richmond, who head the AHA's subcommittee on cardiac emergencies, Arieff's "very enlightening" human study is "driving the nail even deeper into the coffin."
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Title Annotation:cardiopulmonary resuscitation
Author:Hart, S.
Publication:Science News
Date:Aug 5, 1989
Words:648
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