1. Which of the following is NOT a contraindication to declaring brain death?
a) Serum Sodium of 175
b) Core body temperature of 34 C
c) Triple flexion in the lower extremities in response to painful stimuli
d) Serum phenobarbital level of 70
2. Which of the following is NOT a part of the apnea test?
a) Patient must have a change in PaCO2 of at least 20
b) Patient must have a final PaCO2 of at least 70
c) One can insufflate oxygen via a suction catheter hooked up to oxygen supply, CPAP without a backup rate, or a T-piece in order to avoid significant hypoxemia
d) Patient cannot have any evidence of spontaneous respirations
3. What of the following is NOT true regarding radionuclide angiography?
a) It is used as a confirmatory test for declaration of brain death
b) A test with flow only to the major intracerebral arteries is consistent with brain death
c) It is an optional test
d) If the radionuclide angiography is consistent with brain death, one still needs to do an apnea test
4. You are performing the vestibulocular reflex test in your patient you suspect to be brain dead. You inject 50 cc of iced saline into the R ear. What response would be most consistent with brain death ?
a) The eyes turn slowly toward the R side and have a fast beat away towards the left
b) The eyes turn slowly toward the L side and have a fast beat away towards the right
c) Disconjugate gaze occurs
d) There is no response
ANSWERS & EXPLANATIONS
1. C- spinal reflexes can occur even in the presence of brain death. Hence, such reflexes (such as triple flexion of the hip/knee/ankle in response to painful stimuli) do not preclude a diagnosis of brain death. See this article for further examples of spinal reflexes that may occur with brain death.
2. B- the patient must have an ending PaCO2 of at least 60 mmHg, not 70 mmHg. There also needs to be an increase of at least 20 in the PaCO2 without evidence of spontaneous respirations. It is acceptable to insufflate oxygen to avoid significant hypoxemia by any of the methods described.
3. B- the radionuclide angiography is an optional test for the confirmation of brain death. One must still do an apnea test (if possible) even if the results of radionuclide angiography are consistent with brain death. A study consistent with brain death will shown complete absence of blood flow to the normothermic brain.
4. D- in a patient with an INTACT brainstem, the mnemonic COWS (Cold-opposite, Warm-Same) describes the fast beat of nystagmus that occurs normally when cold or warm water is injected into the ear canal, causing changes in the endolymph and subsequent afferent vestibular signaling with resulting nystagmus. Hence, if this patient's brainstem were intact, A would be the correct response, with the fast beat Opposite the side of the injection. However, in this case, if the patient is brain dead, there will be no brainstem function and hence no vestibulocular reflex.