Simple test can catch smokers who fib

By Julie Steenhuysen

CHICAGO (Reuters) - A simple device for detecting carbon monoxide in the blood may help doctors get an honest answer out of patients who smoke, U.S. researchers said on Monday.

The device, called a pulse cooximeter, is typically used to test for carbon monoxide levels in firefighters, but it can also detect carbon monoxide levels in people who smoke, offering a powerful tool for educating patients about the effects of smoking.

"We were trying to just solve a little problem," said Dr. Sridhar Reddy, a lung specialist in St. Clair, Michigan, who presented the study at a scientific meeting of the American College of Chest Physicians in Chicago, along with his 16-year-old son Ashray.

"There is no good way to screen people for smoking," said Dr. Reddy, who encouraged Ashray to take on the study as a school science project.

"You can ask them directly, do you smoke. But once they say they don't smoke and they lie about it, they will never volunteer that information," Dr. Reddy said in an interview.

Dr. Reddy was looking for a quick, convenient method to detect whether a person smokes. Current tests involve breath, blood or saliva samples, but the pulse cooximeter simply involves placing a clip-like device on a finger tip.

The pulse cooximeter reads percentages of poisoned blood through a light that is shined through the finger nail.

Dr. Reddy's son Ashray wanted to find out how much carboxyhaemoglobin -- blood poisoned by carbon monoxide -- would indicate whether a person is a smoker.