Doctors find more colon polyps when their patients are fully unconscious instead of only moderately sedated during colonoscopy exams, U.S. researchers said on Monday.

They said having patients fully sedated during a colonoscopy may allow doctors to focus on the task at hand and do better work.

In the United States, the vast majority of patients are partially conscious during colonoscopies, but new automatic sedation machines, such as Johnson & Johnson's Sedasys device, may allow more patients to be screened, the researchers said.

A colonoscopy is an uncomfortable procedure in which a long, flexible, lighted tube is inserted through the rectum to look for precancerous lesions or polyps in the colon.

During the procedure, the doctor may remove precancerous growths, preventing the development of cancer, and take tissue samples. The procedure can detect colorectal cancer at early stages when it responds best to treatment.

Colonoscopy exams are generally recommended for people age 50 or older, but patients often skip the procedure.

Dr Katherine Hoda and colleagues at the Oregon Health & Science University in Portland studied endoscopy reports on more than 100,000 patients having colonoscopies done under deep sedation or moderate conscious sedation, in which patients can hear and respond to directions during the procedure.

They found that doctors detected 25 percent more large colon polyps when patients were fully sedated compared with those who were moderately sedated, even after controlling for such factors as age, gender and race.

"We feel that this may be because the patient is more relaxed and this allows the physician to focus completely on looking at the screen for polyps," Hoda, who is presenting the study at the Digestive Disease Week conference in Chicago, said in a telephone briefing.

NO ANESTHESIOLOGIST

She said the overwhelming majority of colonoscopies in the United States are done using moderate conscious sedation, typically using a combination of benzodiazepines, which include diazepam — better known as Valium — and an opioid, such as fentanyl and meperidine, better known as Demerol.

"It's still considered the standard, but deep sedation is increasing," she said.

Typically, colonoscopies performed under deep sedation use the short-acting sedative drug propofol, made by a variety of manufacturers as a generic and also by AstraZeneca under the brand name Diprivan.

But in many regions, an anesthesiologist is required to administer the drug. "Typically, when we use an anesthesiologist, it doubles the cost of the procedure," Hoda said.

She said new devices, such as the Sedasys system — which monitors patients' vital signs while intravenously delivering propofol — would allow gastroenterologists to use propofol.

"The device is a way to take the anesthesiologist out of the equation," she said in a telephone interview.

Last month, an advisory panel to the U.S. Food and Drug Administration recommended the device be approved for some patients. A Johnson & Johnson spokeswoman said the company is seeking approval for mild to moderate sedation.

Colon cancer is the second biggest cancer killer in the United States, with 49,920 deaths projected for 2009 by the American Cancer Society and more than 106,000 cases.