Nobody’s Favorite Exam
Colin Son -- I don’t know what your hospital is like, but the patient room we walk into is one of those unique ones crammed into an obscure corner. It is tucked away next to a utility closet and behind a team room. It screws up the numbering for every other patient room down the hall. An oddity of the multiple disorganized architectural revisions this hospital floor has no doubt gone through.
In one of those mysteries of modern life, the automatic door senses when we’re in front of it and slides open. I always expect it to do so with a hiss but that never seems to happen. Through the door I’m asked to practice that saturnine but all important final physical exam. I imagine, when it actually counts, there is nothing too unique about performing an exam to document brain death except in its requirement to be methodological and highly attentive. As I walk myself through the exam this day, in this room, I wonder if that is ever difficult; if bias ever hampers the whole thing. I mean, I had seen this gentleman’s CT scan. Maybe not. Certainly not during my first time through it, even if my exam doesn’t contribute anything to the outcome.
Brain death is something that deserves and has legal definitions. While the specifics of some of the laws vary by locale, in general the physical exam to document brain death is pretty standardized.
Foremost you need to rule out anything, other than permanent loss of function, which could be depressing the brainstem. Things to think about include:
- Intoxication or other depressants
- Hypoglycemia or other metabolic problems
- Paralytic agents
With those met, the physical exam can be performed. The standard of care through most places is an exam by two experienced physicians with each exam spaced by at least half an hour. In the U.S. some states require an EEG (or two separated by some time period). Some places even use radionuclide scans to document brainstem metabolism.
As for the physical exam itself, you’re testing brainstem function:
- Gag reflex
- Pupillary reaction to light
- Corneal reflex
- Oculocephalic reflex
- Vestibuloocular reflex
- Cranial nerve response to painful stimuli
- Apnea challenge
All of the above have to be negative.
The gag, pupillary light, and corneal reflexes are pretty typical. I’ll just clarify the others for completeness sake. The oculocephalic reflex is the doll’s eyes reflex. With an intact brainstem the eyes should fixate on a point. With their eyes open you take the patient’s head and turn it back and forth. If the eyes remain unchanging in their gaze then the reflex is absent. The vestibuloocular reflex is also known as the caloric test. For this test you typically use cold water. Inserted into the external auditory canal, the water should elicit eye movement if the reflex is present. The old mnemonic COWS (Cold Opposite, Warm Same), which refers to the direction of the primary movement based on the temperature of the water inserted into the canal, really isn’t important in a brain death exam. Any eye movement during caloric testing is enough to preclude a declaration of brain death. Finally, the apnea challenge just refers to disconnecting the patient from their ventilator and allowing the pCO2 to rise. If the hypercapnia will not evoke respiratory efforts in the patient, then the test is negative.
With all of those reflexes run through I follow my team out and up to the call room. I’d bet not the last time I’ll make that walk.
Thanks Colin! I would not perform the exam and declare somebody's brain dead from the first time. Im pretty sure that even brain death " experts" hesistate before giving their final word on any particular patient. It is a tough decision, indeed.
Posted by: Surgeon | Jul 25, 2008 4:18:55 AM
Extremely well written. And informative too. I could imagine myself performing the entire exam.
Posted by: | Jul 25, 2008 3:25:10 PM
must have been scary doing that and just imagine if the gentleman woke up!! boy! no more horror films for me!but thanks for the informative write up.. i vaguely remember the oculocephalic reflex but now its crystal clear.
Posted by: anuja | Jul 26, 2008 5:54:19 AM
You didnt tell us about the cranial nerve response to painful stimuli
Posted by: Jackson | Aug 4, 2008 5:11:43 AM
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