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Quick New Test Detects Cyanide Exposure in Fire Victims

October 22, 1996

NEW ORLEANS (AP) _ Where there’s smoke there’s often cyanide _ but it kills so quickly and the tests take so long that doctors rarely check for it.

Now scientists have developed a quick new test for cyanide exposure that could save some people who now die of smoke inhalation.

The test uses equipment already found in most hospitals and yields results in 40 minutes, said Dr. Avery Tung, the University of Chicago anesthesiologist who developed it. Doctors can then administer cyanide antidotes that are either inhaled or injected.

Current tests for cyanide are all but useless. They take up to four hours, and because most hospitals rely on an outside lab to perform them, it can take days and even weeks to actually get the results back.

Doctors can’t simply go ahead and administer the antidote on the mere suspicion that a patient was exposed to cyanide. Unless there is a substantial amount of cyanide to treat, the antidotes themselves can kill.

Tung, who presented the test Tuesday at a meeting in New Orleans of the American Society of Anesthesiologists, eventually hopes to develop a test that can be performed at fires.

Plastic, paint, varnish, lacquer, wool and silk all can release cyanide when burned. It kills by preventing cells from using oxygen.

``If cyanide is present, if you do not treat the cyanide poisoning itself, no matter how much oxygen you give a patient he’s not going to be able to use it,″ Dr. Paul Matera, an emergency room physician at Providence Hospital in Washington said in a telephone interview.

A study in England during the 1980s found cyanide in the blood of nearly half of the people suffering from carbon dioxide poisoning caused by smoke inhalation, said Dr. Larry Weiss, director of emergency medicine at Lousiana State University’s Medical School.

However, such tests are rarely ordered unless a doctor knows that the fire burned something likely to release large amounts of cyanide.

``We don’t usually test for it, because if you don’t treat it immediately, it’s too late,″ Weiss said.

Tung’s test adds a chemical compound called methemoglobin to a blood sample. If there is cyanide in the blood, it changes color. A spectrophotometer _ fairly standard equipment in hospitals _ reads the results to find out how much cyanide is in the blood.

Current tests are more complicated. One requires a series of three chemical reactions, Tung said. The other uses an expensive machine that measures electrical conductivity in liquids.

A quick, reliable cyanide test could make a big difference in how patients are treated, Matera said. ``It’s certainly something I would use, especially if a patient wasn’t getting any better,″ he said.

Tung said nearly all of his experiments have used blood to which he added cyanide. He said he also tried the test on a few cases of smoke inhalation, but the patients’ cyanide levels were too low to warrant treatment.

Tung said he hopes to develop a stripped-down machine that ambulances could carry to fires. In addition, he said, he is working on a test that would check the amount of cyanide in a person’s breath, instead of blood.

Such a test also could be used to check miners and factory workers who are likely to breathe small amounts of cyanide on the job, Tung said.

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