Determining Brain Death: 1/3

Several months ago, I skewered a Hallmark movie for its unrealistic portrayal of discontinuing life support. In light of that, I thought I'd do a special series on determining brain death.


How do medical personnel determine a patient has suffered brain death?

Brain death means that your brain as an organ has died. It is no longer receiving blood flow. Without blood flow, no oxygen is being delivered. Without oxygen, an organ dies. Your brain is your body's main control. If it has died, you have died.

If you have a character that is brain dead, they should be on life support. Again, if the brain isn't working, it's not telling your lungs to inhale. However, we can do this medically with a ventilator. This is why families sometimes have trouble understanding brain death means ultimate death. If we provide oxygen to the lungs, the heart will continue to beat and bodily functions can be maintained for a limited amount of time. A family sees the rise and fall of the patient's chest and assume the patient is initiating those breaths when in fact it is the machine doing all the work.

There are several ways to determine brain death. Some are not as precise as others. I'll try to cover least precise to most precise.

Before testing, there is generally an observation period. My hospital uses the following guidelines:

Less than 7 days: Not applicable
Age 7 days-2 months: 2 exams 48 hours apart
Age 2-12 months: 2 exams 24 hours apart
Over 12 months: 2 exams 12 hours apart
Adults (18 years and older): 2 exams 6-12 hours apart.

Also, prior to the exam to determine brain death, the patient must also meet the following criteria:

1. Absence of a reversible condition. The cause of the coma must be documented.

2. Absence of hypothermia. The patient must have normal body temperature.

3. Absence of hypotension. The patient must have normal blood pressure.

4. Absence of drugs or toxins in significant amounts as to interfere with the diagnosis of brain death.

5. Absence of a metabolic cause of the coma.

6. Normal levels of carbon dioxide.

Once these are met, the patient should be observed for the following:

1. No cranial nerve reflexes. Here is an extensive list of what those are: http://www.clinicalexam.com/pda/n_cranial_nerves_exam.htm

2. Flaccid tone in all extremities.

3. No response to deep pain.

Once these are met, the patient proceeds to apnea testing. That’s where we’ll pick up next post.