Brain Death Criteria Revived!
Andrew Wilner, MD, Neurology, 02:17PM Jul 21, 2010
Dead or Alive?
What could be more essential for a physician than to know whether a patient is dead or alive, particularly if someone is about to harvest the patient’s organs? Even a tiny mistake in the determination of brain death changes the donor’s charity into a suicide and the harvester’s surgery into murder.
So it’s nice to have an up-to-date brain death guideline.
In 1995, the American Academy of Neurology published a useful guideline for the determination of brain death (AAN 1995). When I recently examined an unfortunate 44 year old woman who suffered a severe hypoxic-ischemic brain injury due to a drug overdose, I relied on this guideline to arrive at a diagnose of brain death. I needed to be able to comfort the family prior to her organ donation and convince myself, that she was, indeed, brain dead. (Although she had no brainstem function,
she had tremors of her upper extremities. But the 1995 guideline reassured me, “Spontaneous movements of limbs other than pathologic flexion or extension response…are occasionally seen and should not be misinterpreted as evidence for brainstem function”.)
I was also reluctant to make the diagnosis because I knew that a new brain death guideline was about to be published, but it was still a week away. Why a new guideline? Would anything change? I breathed easier today when I read, “The criteria for the determination of brain death given in the 1995 AAN practice parameter have not been invalidated by published reports of neurological recovery in patients who fulfill these criteria.” Whew!
The new AAN brain death guideline for adults (>18) is endorsed by the American College of Radiology, Child Neurology Society, Neurocritical Care Society, and the Radiological Society of North America.
The authors posed 5 clinical questions:
1. Are there patients who fulfill the clinical criteria of brain death who recover neurologic function?
2. What is an adequate observation period to ensure that cessation of neurologic function is permanent?
3. Are complex motor movements that falsely suggest retained brain function sometimes observed in brain death?
4. What is the comparative safety of techniques for determining apnea?
5. Are there new ancillary tests that accurately identify patients with brain death?
A review of 38 articles that met search criteria arrived at only “Level U” recommendations (studies not meeting criteria for Class I-III) for 4/5 questions due to the lack of evidence-based research. However, question #3 achieved a “Level C” recommendation (requires at least one Class II study or two consistent Class III studies).
Consequently, the new guideline is essentially “opinion-based.” Until evidence-based studies become available, the authors offered “Practical Guidance for Determining Brain Death,” briefly summarized below:
1. Establish irreversible and proximate cause of coma.
2. Exclude the presence of CNS drugs, neuromuscular blockade, or severe electrolyte, acid-base, or endocrine disturbance.
3. Achieve normal core temperature (>36 degrees C).
4. Achieve normal blood pressure (systolic >100 mm Hg).
5. Neurologic exam (one exam is sufficient in most states) consistent with brain death includes:
A) coma (lack of responsiveness)
B) absence of brainstem reflexes
C) absence of ocular movements using oculocephalic testing (Doll’s eyes) and oculovestibular reflex testing (calorics)