How I do a brain death examination: the tools of the trade
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EDITORIAL
How I do a brain death examination: the tools of the trade Eelco F. M. Wijdicks*
Brain death has been accepted universally, although practice differences have eluded consensus [1, 2]. Laws and guidelines have not appreciably changed [3, 4] nor have tools of the trade. The following principles remain: establish the reason for coma (most important), exclude known/unknown confounders (equally important), ascertain the futility of intervention (decided before), prepare the patient for testing (to optimize resolution), and acknowledge clinical examination as the benchmark (essential) [5]. One should ask three questions: Have I tried everything to change the clinical picture? Can I proceed? Can I be fooled? Brain death examination is hands-on (Fig. 1) and focused on brainstem function: from mesencephalon down to the dorsal medulla oblongata. These seemingly few tests are more than sufficient; other tests (e.g., IV atropine, nasal tickle, and ciliospinal reflex) add nothing. In the mesencephalon, test only one reflex circuit, the pupil response to a high-intensity flashlight. Pupils in brain death are not “fixed and dilated” but mid-position (4–6 mm) due to loss of sympathetic and parasympathetic input. I use a magnifying glass while others use a pupilometer; the only difference between them is several thousand dollars. Several reflex circuits are tested in the pons: absent corneal reflexes; squirt water on the cornea or strike with cotton from the conjunctiva toward and on the cornea. (Sadly, one in five surveyed members of professional organizations does not test correctly [6]). To elicit the oculocephalic reflex, hold the head firmly with two hands while keeping the *Correspondence: [email protected] Neurosciences Intensive Care Unit, Saint Marys Hospital, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
eyelids open with thumbs. Eye movement (opposite to head movement) is induced by fast head turning from a middle portion to 90° on both sides. (Obviously, omit this test in a trauma patient with a cervical collar.) Also, eye movements should be absent after irrigating the tympanum with 30 cc ice water. (The normal response in a comatose patient is a very slow deviation of the eyes toward the syringe.) I place pen marks on the eyelid to reference the level of the pupil. Pain grimaces should be absent upon deep pressure to nail beds (reflex hammer), pressure on the supraorbital nerve (thumb), or deep pressure on the temporomandibular joint condyles (index fingers). In the medulla oblongata, test the gag response with a tongue depressor or suction device into the oral cavity. As it is difficult to see, I insert a gloved finger past the uvula, a more reliable stimulus. Catheter passages through the endotracheal tube while providing suctioning pressure should not elicit a cough response. Noxious stimuli should not produce a motor response. While there might be a spinally mediated response (i.e., brief, slow movements in the upper limbs, flexion in the fingers, or arm lifting), they are nev
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