Chapter 36: Ethics, Death, and Organ Donation
What is a contraindication to apnea test?
B. Chronic carbon dioxide retainers
High cervical cord lesions; GBS; toxicities such as organophosphate, baclofen, lidocaine, and vecuronium; and locked-in syndrome can be mimics of brain death with temporary or permanent absence of brainstem reflexes and even unresponsive pupils. Although eucapnia is a prerequisite for the apnea test, some authors suggest it can be used in CO2 retainers. First, the CO2 baseline is reached. During the test, a PCO2 greater than 20 mmHg from baseline with a pH less than 7.28 suggest a positive apnea test., (choice B). Despite hypotension being the main complication of the apnea test, the use of pressors before the apnea test does not exclude them from the test. Pressors are titrated to maintain a mean arterial pressure above 100 mmHg, (choice A). The cutoff temperature to perform the apnea test is 36°C. (choice D).
A 52-year-old man with past medical history of cerebrovascular accident (CVA) causing trochlear nerve palsy, was brought in by emergency medical services after sustaining ventricular fibrillation arrest outside of the hospital. Family members report that patient was likely down for 10 minutes before initiation of CPR. The patient had return of circulation (ROSC) after 12 minutes of CPR and was intubated in the field. A cooling protocol was initiated, and the patient is now 24 hours after rewarming. He shows no response to external stimuli. A neurologist is present and is performing a neurologic examination to initiate certification of brain death. In this patient, which element of the neurologic examination may not be accurate given patient’s past medical history?
B. Vestibulocephalic reflex
To test this reflex, the patient’s eyelids are held open, and the head is flexed and extended; if the reflex is intact, the eyes will move in the contralateral direction to head movement. This reflex, along with the oculocephalic (doll’s eyes) is usually specifically the vertical portion of oculocephalic testing. Vestibular cephalic reflexes (choice B) test CNs III, VI, and VIII. Because the doll’s eyes reflex involves vertical movement of the eyes and this patient has some unspecified problem with one of the CNs that is involved in vertical eye movement (CN IV, trochlear), this may confound the test. The corneal ...