Certain tests can predict with great accuracy whether a person in a coma after CPR (Cardiopulmonary resuscitation) will have a poor outcome, according to new guideline developed by the American Academy of Neurology. The guideline is published in the July 25, 2006, issue of Neurology, the scientific journal of the American Academy of Neurology.

Poor outcome was defined as: death; unconsciousness after one month; or unconsciousness or severe disability after six months.

“This guideline will help physicians predict the outcome for these patients and then communicate that information to family members,” said guideline author Eelco Wijdicks, MD, of the Mayo Clinic in Rochester, MN.

To develop the guideline, the authors reviewed all of the available scientific studies on the topic.

The main tools to predict outcome are the doctor’s clinical examination of the patient and laboratory tests.

“Certain tests have a false positive rate of zero,” Wijdicks said. “This means that if the test determines that the person will have a poor outcome, there is virtually no chance that the test is incorrect.”

Wijdicks also noted that there are currently no tests that accurately predict which patients will have a good outcome.

Tests that are strong predictors of poor outcome include absent pupillary reflexes or corneal reflexes. The pupil, the black part of the eye, usually gets smaller when light is held in front of it. The eye normally blinks when the cornea, or the clear part of the eye, is touched with a small piece of cotton or dripping water solution.

Absent or extensor motor responses three days after cardiac arrest are another strong predictor of poor outcome. An absent motor response means there is no movement in response to pain. An extensor motor response is a reflex movement with straightening of the arms and legs. The movement happens on its own or in response to pain.

The guidelines also determined that some factors and tests are not good predictors of poor outcome from coma. The circumstances surrounding CPR, such as how long CPR is conducted, the cause of the cardiac arrest, and the amount of time that passes between the cardiac arrest and the start of CPR do not accurately predict the outcome from coma.

“In the midst of a catastrophe, families are subsumed with grief from an ordeal that undermines all their coping mechanisms,” Wijdicks said. “It’s important for family members to talk with a neurologist when faced with this situation. Neurologists can provide accurate information about assessment and the likelihood of recovery. If the probability of devastating neurological disability is high, family members may prefer no further resuscitation, no surgical interventions or the withdrawal of critical care. These decisions should be made after understanding the patient’s prior advance directives, or instructions for what type of care the patient would like to receive.”

American Academy of Neurology (AAN)