U.S. researchers have developed a new tool that may help neurologists identify which coma patients are potential organ donors, a development that could potentially boost organ donation rates.

Coma patients with irreversible brain damage are often good candidates for organ donation when they die because their other organs are generally healthy. However, the donation must occur within 60 minutes of when the heart stops beating.

"Neurologists must often predict whether the patient will be a candidate for organ donation, but the existing tools are not designed for people with critical brain disease," study author Alan Yee, of the Mayo Clinic in Rochester, Minn., said in a news release.

Yee explained that current tools, for example, require the patient to be taken temporarily off ventilator support to conduct the test. The new test, designed for people with irreversible brain damage, "is a significant improvement because it can be conducted before the patient is taken off breathing support," he said.

Yee and colleagues studied 149 coma patients who were taken off life support and identified a number of factors that strongly indicated a person with irreversible brain damage could be a potential organ donor. The four factors are:

• No corneal reflex. This is tested by touching the cornea with a small piece of cotton or dripping water solution to see if the patient blinks.
• No cough reflex. To check this response, a chemical irritant is placed near the patient in order to see if they cough to expel the irritant.
• No motor response to pain or extensor movements that occur on their own or in response to pain. Extensor motor movement is a reflex straightening of the arms and legs.
• High scores on the oxygenation index, which is a test of how well the lungs are working.

Coma patients with all of these factors were 93 percent more likely to die within 60 minutes of being taken off life support than patients with none of these factors. Patients with one of the four factors were 65 to 76 percent more likely to die within 60 minutes.

The study appears in the April 27 issue of the journal