Hello, this is Dr. David Greer from Boston University School of Medicine and Boston Medical Center, and I'll be speaking to you about key components and special considerations of the brain death slash death by neurologic criteria examination. These are my disclosures. None of these have pertinence or direct relation to today's lecture. Here are the objectives for my talk. First is to identify potential confounders for the brain death slash death by neurologic criteria determination. Second is to recognize proper technique for examination, including apnea testing. Third is to explain indications for an appropriate use of ancillary testing. And fourth is to explain new special considerations in the 2023 update to the guidelines, which were a joint effort between the American Academy of Neurology, the American Association of Pediatrics, the Child Neurology Society, and the Society of Critical Care Medicine. First, we should discuss how does brain death occur. So there is some kind of a primary insult, which can commonly be a cardiac arrest, but can be any form of stroke, subarachnoid hemorrhage, traumatic brain injury, even a brain tumor. And then there's secondary increased intracranial pressure that compromises cerebral perfusion. In fact, it compromises it to the point that there's secondary ischemic injury, which causes additional swelling and injury to the brain. You get herniation, which compromises vital structures, including, most importantly, the brain stem, which is typically the last to go. And there's insufficient blood flow and hypoxia, which kills the remaining neurons. Remember that your skull is a very fixed and rigid container. It doesn't allow for a lot of extra swelling. So as the intracranial volume goes up at a certain inflection point, the intracranial pressure goes up exponentially. And that's likely the point of no return when there's herniation downward through the foramen magnum. This picture illustrates some of the potential different causes for a brain death. And you can see in the A panel is a subdural hematoma. Panel A and B is what looks like a subarachnoid hemorrhage, but is more likely a cardiac arrest with a pseudo-subarachnoid hemorrhage sign. Panel C is an intraventricular hemorrhage. Panel D is a massive ischemic stroke involving the left hemisphere, also shown in panel E. And panel F and G are interesting. That's the same patient, but it's a patient with a posterior fossa cerebellar stroke, which by itself might not cause brain death. But with secondary injury and swelling, you can see that this patient has developed catastrophic hydrocephalus. If that hydrocephalus is not treated based on the condition of the patient or the goals of care, and there's secondary concomitant supertentorial injury, that patient can still be declared brain dead. But this is new in the guidelines that you have to have evidence of both infratentorial and supertentorial catastrophic injury based on neuroimaging. So let's talk about the new guidelines, which came out in October of 2023. And hopefully, we're a giant step forward for the field. You see that the first word for the guideline is now pediatric and adult. And that's a new thing. It's a combination of pediatric and adult under one guideline, which is the first time that that's been done. And we felt that this was important because most of the principles, probably about 90 to 95%, are shared between adult and pediatrics. But there need to be appropriate carve-outs for pediatrics based on their physiology and age. For example, the blood pressures are different between children of different ages. And so that needs to be known. And the cranial physiology with the open fontanelles and sutures until about the age of 1 1⁄2 or 2 years will certainly affect the patient's development of brain death. We provide stringent conservative guidance to minimize the possibility of false positive determination. In fact, this is the one disease in neurology where I feel that we have to be 100% accurate when we make this diagnosis. If there's any possibility that the patient is not brain dead, we do not want you to declare them so. So this should be a very highly meticulous process erring on the side of not declaring somebody brain dead. The new guidelines provide guidance around aspects that clinicians find challenging or controversial, including procedures to lower the intracranial pressure. That means you have a patient who has a lesion with mass effect and you think it might be reversible and you decide to treat it, whether it be with eyebrows molar therapy or even with surgery. We provide guidance about how long do you wait after you've done such a procedure or an intervention. This didn't exist before. We provided, as I said, new guidance regarding primary infertentorial injury. We provide guidance regarding patients on ECMO, patients who have received therapeutic hypothermia or were environmentally exposed to hypothermia, pregnant persons, consent and whether that should be required. And we provide some guidance regarding preserved neuroendocrine function and whether you can continue with brain death determination in that setting, which you can't. First of all, some terminology. You've already heard me say brain death and death by neurologic criteria. The colloquial term is brain death. The more accurate term is death by neurologic criteria, but that's a mouthful. And so we've kind of combined it into one thing, BD slash DNC to encapsulate both words. We've changed the word irreversible to permanent, which means that function is lost and A, won't resume spontaneously and B, medical interventions will not be used to attempt to restore functions. That should probably say medical and surgical interventions will not be used. We defined a child as at least 37 weeks old, corrected gestational age, but younger than 18 years old. And we said that in infants younger than 37 weeks, corrected gestational age, you cannot determine brain death in that age group. It was just too young to know what would be considered permanent for the brain injury in that population. So you have to be at least 37 weeks old to be determined brain dead. This should be obvious, but there needs to be a clear separation from organ donation. To avoid a conflict of interest, clinicians who are involved in brain death determination must only consider the interest of their patient and avoid any direct involvement in decision making regarding organ donation. And obviously any clinician involved in surgical recovery of organs such as a transplant surgeon must not be involved with a brain death evaluation. Now this does not mean that we as intensivists are blind to the fact that these patients can be organ donors. However that is not the primary motivation for us to be determining brain death. This is a diagnosis like any other that should be made when it is occurring. And we can introduce representatives from the organ procurement organization. However we are not directly involved in those due to a necessary decoupling of those conversations. Who can perform a brain death evaluation? So we said that attending clinicians must be appropriately and adequately trained and competent in the evaluation of brain death in accordance with local laws and institutional standards. We said that APPs can determine brain death if in accordance with local laws and institutional standards and with appropriate training. However in settings where APPs are not permitted or if the patient is a trainee, they must be directly supervised by an attending. A trainee consists of a completion of a supervised brain death evaluation in a clinical environment which is considered a gold standard or a well-designed in-person training course which is the next best thing or a well-designed online training course and those are available through the Neurocritical Care Society. In terms of prerequisites, you really have to know the cause of the brain injury and that sounds obvious but sometimes that rule is overstepped. You must ascertain that the patient has sustained a catastrophic permanent brain injury caused by an identified mechanism known to lead to brain death before initiating a brain death evaluation. You should conduct further diagnostic evaluation and not undertake brain death testing if the patient is comatose, apneic and has absent brain reflexes but there is no identified mechanism of brain injury that is known to lead to brain death. And importantly, we really strongly recommend that everyone get neuroimaging that is consistent with the mechanism and severity of brain injury before starting your brain death determination. So having proximate neuroimaging that is compatible with brain death is super important. You have to know that the condition is permanent. So for infants and children younger than 24 months old, you have to wait at least 48 hours after the acute brain injury regardless of the cause. In an adult, that is going to be potentially different in a shorter period of time but in children, if you are younger than 24 months, regardless of the brain injury, it has to be at least 48 hours. You have to wait a sufficient amount of time to know that there is no potential for recovery of brain function and that observation period should be based on the pathophysiology of the brain injury and that can be different based on the different etiologies that lead to brain death. In patients who have suffered a cardiac arrest, you have to wait at least 24 hours in adults and again in children within at least 48 hours if they are younger than age 24 months. If they are older than age 24 months, regardless of how much older they are than 24 months, you have to wait at least 24 hours after a cardiac arrest. In terms of the medical or surgical interventions that are used to treat elevated intracranial pressure, you have to wait a sufficient amount of time to ensure that there is no recovery of brain function and that is going to be based on whatever the etiology is. If it is TBI, it might be longer or shorter. If it is a subarachnoid hemorrhage, it might be days. If it is a cardiac arrest, it might be as short as 24 hours but no shorter than that. The patient's temperature has to be at least 36 degrees regardless of the age. Those were different in prior guidelines and now it is 36C for everyone. In someone who has been less than 35.5, you have to re-warm them and you have to have them at least 36 for at least 24 hours if they had been hypothermic previously and that is new guidance. In terms of the blood pressure, again they obviously can't be hypotensive and you should administer crystalloids or colloids or vasopressors or inotropes as needed to get an adequate blood pressure and that blood pressure now has a systolic and a mean arterial pressure goal. Systolic has to be at least 100 and the MAP has to be at least 75. In children, it should be at least a fifth percentile based on their age and keep in mind that these values are applicable for patients who are on VV ECMO as well which is obviously pulsatile. If someone is on VA ECMO, you can only go by the MAP which still has to be 75 or greater or in children at least a fifth percentile. If the patient has a baseline blood pressure that is significantly higher, then you really want to shoot for their baseline blood pressure if it is known. For example, if somebody lives with a systolic of at least 200 and you know that, then that should be the blood pressure that you are starting with to be your baseline because that is what their brain is used to seeing. These prerequisites should look fairly familiar because they are consistent with prior guidelines. You need a urine and blood tox screen and a blood alcohol level of less than or equal to 80. If you have levels for known meds that can suppress CNS function, then you have to be in the therapeutic or sub-therapeutic range. You have to allow at least five half-lives and longer if they have renal or hepatic dysfunction or are obese or hypothermic. You have to account for age-dependent metabolism in children or older adults. If they receive pentobarbital, you have to have a level of at least, I'm sorry, less than five and you have to exclude severe metabolic acid-base or endocrine arrangements and if they receive paralytics, you have to make sure they are no longer paralyzed and you can do this either with a train of four or by using deep tendon reflexes. Here's new guidance regarding some of the values that can be acceptable or unacceptable in patients who are being considered for metabolic derangements in brain death and this is again new guidance. Please keep in mind that this is based on consensus only and you have to use your judgment around these, but this is some general guidance that may be helpful for you. Here's other new guidance from the new guidelines regarding specific meds. I haven't shown all of them here, but these are some of the common meds that are used and how they metabolize differently in children versus adults and special considerations that may prolong the half-life and make you wait for longer. What if you can't correct the metabolic derangements? So you still do all of the neurological examination and the apnea tests and I put the possibly plural because in children you have to do two apnea tests, so you still do the full clinical evaluation and if that is consistent with brain death and DNC, then you still have to perform an ancillary test. The key here is that you don't go directly to an ancillary test even when you know you can't correct the derangements because if you find signs of life on their clinical evaluation including the apnea test, they are not brain dead and an ancillary test is not indicated. So you always test everything you can when you can. How many examinations are required? Well in adults, it's a minimum of one, but we really recommend two. That's probably the best compromise we can come up with by saying that two independent examinations may decrease the risk of false positive determinations and I think personally it should be two independent and blinded evaluations by attending clinicians or in the jurisdiction that allows it with an APP as well. In adults, a second exam will likely provide a fail-safe. In children, you always have to do two clinical evaluations and you have to do two apnea tests as I said and there should be 12 hours that separate the two examinations in children only. There is no need for a separation in adults. Again you never go straight to ancillary testing, you test everything you can when you can including the apnea test and if you find signs of life, the patient is not brain dead and you don't get an ancillary test. In terms of the neurological assessment, there are three cardinal features. Number one, coma. Number two, absence of all brain stem reflexes and number three, apnea. Coma means complete unresponsiveness, no eye opening or eye movement to noxious stimulation. There's no blink to visual threats, no response to loud voice. Noxious stimulation produces only spinally mediated responses or none. You have to stimulate in all four extremities and on the cranium. Simulation on the cranium can be at the superorbital notch, it can be at the temporomandibular joint or you can even do a nasal tickle with a Q-tip. Sometimes you'll see movements that are hard to distinguish whether they're cerebrally or spinally mediated so get somebody else to take a look and see if it looks like it's cerebrospinal and if there's still a question, you may need to get an ancillary test in addition to the clinical testing in that patient. There are many reported spinally mediated reflexes, this is just a list that comes from the new guidelines which can be a good reference for you. In terms of the clinical evaluation, the pupillary exam is obviously quite central to this. There should be no pupillary response to bright light in either eye. Constrictive pupils are fixed and usually 4-6mm, they can be anywhere between 2-9mm but keep in mind that constrictive pupils that are specifically less than 2mm should suggest possible drug intoxication and you may need an ancillary test in that setting as well. I recommend using a magnifying glass and or a pupillometer as a fail-safe to see if there is any pupillary reaction. The corneal reflex should be tested with adequate stimulus. What does this mean? Well, people typically test this wrong and in order to show an adequate stimulus, you actually have to take a Q-tip and press on the eye and see it move slightly and where you touch on the eye is crucial. If you touch far laterally on the sclera, it may be less sensitive so I recommend touching right adjacent to the iris where the eye is still quite sensitive and with a little Q-tip pressure which I'll show you in a little bit. The oculocephalic reflex should be only tested with the integrity of the C-spine ensured and an intact skull base. You briskly rotate the head horizontally, you can do it vertically as well and you should see no movement in brain death. Regarding these, the OCR should again only be performed when there is an intact cervical spine and skull base. If the oculocephalic is absent bilaterally or the oculocephalic cannot be performed, you still must do the oculovestibular or the colcaloric. The oculocephalic is the only part of the clinical exam that you can skip if you have to and still do a full clinical determination as long as you can do the oculovestibular and there's no confounding for that. This doesn't mean you skip it every time because if you find an intact oculocephalic, you don't need to do an oculovestibular because you know that that's intact, but if you must skip it, this is the only thing you can skip in the clinical exam. The oculovestibular test or the colcaloric, first you ensure the auditory canal and TM are intact. You elevate the head of the bed to 30 degrees, this gives the proper orientation of the horizontal semicircular canals. You irrigate one ear at a time with ice water continuously and you observe for eye movements for at least one minute. You always test both ears and you wait five minutes before testing the opposite ear to let the endolymph and the canals re-equilibrate to normal temperature. Confounders for the oculocephalic and oculovestibular include ototoxic drugs, which you see listed there. If this has caused a known injury to the ears, which you may or may not know, if there's trauma or edema of the face globes or orbits or petrous bones, such as in a TBI patient, it may be causing a restrictive defect that the eyes can't move. And so in that setting, you still test it if you can, but you may need to get an ancillary test. Lower brain stem testing is used to assess facial movement to noxious stimulation, again, the places I told you before, the nasal tickle, pressure on the TMJ, or superorbital ridge or notch. Facial myokinias are permissible. These are spontaneous discharges from a denervated facial nerve, but they cannot occur in response to anything you're doing to the patient. There should be an absent gag reflex by stimulating the posterior pharynx with a tongue blade or a suction device. There should be an absent cough reflex with deep tracheal suctioning to the level of the carina or beyond. And, of course, the patient should have no spontaneous respirations. I'm now going to show you a brief video of the brain death evaluation. Test the auditory response by calling the patient's name loudly. Mr. Jones, open your eyes. Rub the sternum. Apply supraorbital pressure or pressure at the temporomandibular joint. Apply deep noxious stimulation to the nail bed and proximally on all extremities. In a brain death patient, noxious stimulation should not produce grimacing, facial muscle movement, or a motor response of the limbs other than spinally mediated reflexes. Note that patients with severe peripheral neuropathy or cervical spinal cord injury may not elicit a motor response. To assess for a blink response to visual threat, bring the examiner's hand directly into the center of their field of vision at close range and observe whether they blink. In the case of brain death, this should not elicit a blink response. To test cranial nerves 2 and 3, open the eyelids and assess the position of the eyes and size of the pupils. In brain death, the eyes are typically mid-position and fixed. In brain death, the pupils should be in mid-position and typically 4 to 6 millimeters in diameter, but they can be any shape. Small-diameter pupils less than 2 millimeters are not consistent with brain death and may suggest the presence of medications or toxins like narcotics, or that the patient is potentially in a locked-in state in which a patient cannot move due to damage to the corticospinal tracts. Examine a bright light in each eye to test the pupillary light reflex. A magnifying glass helps the examiner identify any evidence of pupillary reactivity. In brain death, the pupils are non-reactive to both direct and consensual stimulation. One can also use an automated pupillometer, although this has not been studied systematically in brain death and should not be used in isolation. Beware that intraocular installation of mediatic medications may temporarily render pupils non-reactive. Additionally, ocular or corneal trauma, orbital edema, or anophthalmia may preclude adequate pupillary evaluation requiring the use of ancillary testing. To elicit the corneal reflex, which is mediated by cranial nerves 5 and 7, apply pressure to the cornea at the border of the iris in both eyes using cotton swab on a stick and monitor for a blink response or more subtle closure of the eyelids. No eyelid movement should be seen in brain death. Be careful not to damage the cornea. Insert a cotton swab into the naris to assess for facial movement. There should be no facial movement. Perform the oculocephalic test, also called the doll's head maneuver, only in patients with a stable cervical spine, and make sure the endotracheal tube remains secure during these maneuvers. Open the eyelids and rapidly turn the head side to side. Be careful for any eye movement in response to head turning. There should be no movement with brain death. Before performing the oculovestibular test, also called the cold caloric test, assess the patency of both auditory canals and the presence of intact tympanic membranes. If the tympanic membrane is not intact, installation of fluid could cause an infection. To perform the oculovestibular test, elevate the head of the bed 30 degrees. Have one examiner hold the eyelids open, while a second examiner instills 50 milliliters of ice-cold water into the ear canal using tubing long enough to reach the middle ear while observing the eyes. In a normal patient, the eyes would have a slow component of tonic deviation towards the cold water, followed by a fast component of nystagmus in the opposite direction. Observe the patient for eye movement for 60 seconds, during which the installation of the cold water should be continuous. Wait five minutes for temperature re-equilibration before repeating this assessment on the other side. No eye movement is seen in a brain-dead patient. The cough and gag reflexes test cranial nerves 9 and 10. To perform these assessments, stimulate the posterior oropharynx on both sides with a tongue depressor or rigid suction device. Stimulate the tracheal and bronchial walls with deep suctioning through the endotracheal tube to the level of the carina. Both gag and cough reflexes are absent in a brain-dead patient. As with the pupillary reflex assessment, ocular trauma, orbital edema, or anophthalmia may preclude full eye evaluation, necessitating the use of ancillary testing. Any patient-initiated eye movement or eyelid movement in response to corneal stimulation precludes a diagnosis of brain death. If the cervical spine is unstable and oculocephalic testing cannot be performed, ancillary testing is not needed, provided that oculovestibular testing, which is more sensitive, is still able to be performed. Ancillary testing is also recommended in persons with injury to the upper cervical spine because the cough reflex can be absent due to injury of the phrenic nerve in this setting. In infants and children, also assess the absence of sucking and rooting reflexes. So this should be only performed by skilled providers. Before attempting apnea testing, you must ensure that the risk of cardiopulmonary decompensation is acceptable. Specifically, you have to ensure that the patient is not hypoxemic, hypotensive, or hypovolemic before starting the apnea test. The prerequisites, again, include normal tension, which is defined as a systolic of at least 100 and a MAP of at least 75 in adults or above the fifth percentile for age in pediatrics. This is with or without vasopressors. Now I'll say that if somebody is borderline with their blood pressure, I like to give a buffer and have a systolic of at least 110 or 120 ahead of time because you don't want them getting hypotensive during the examination. So give yourself a bit of a buffer. Again they have to be normothermic of at least 36 degrees Celsius. They have to be euvolemic, and this is particularly important in patients who have diabetes insipidus who can get a negative fluid balance due to that condition. You should correct their fluid balance so that they don't get hypotensive during the evaluation when they're getting acidotic. You establish eucapnea unless they are a CO2 retainer, which I'll get to in a minute, and you establish a normal pH between 7.35 and 7.45. You correct hypoxia as you're able, and I recommend having a functioning A-line for blood pressure monitoring and ABGs in every patient when possible. You pre-oxygenate patients to at least a PaO2 of 200. You reduce the PEEP to 5 in adults, and if they desat at a PEEP of 5, then that should give you some pause. It doesn't mean you can't do the evaluation, but that may be a patient more at risk for hypoxia. You may obtain a baseline ABG, and I recommend disconnecting the patient from the ventilator. There's no question of whether the patient triggered a breath in that point. There are alternative methods that can be done with the ventilator, which I'll talk about in a second. You continuously provide oxygen to the level of the carina with a catheter placed in the endotracheal tube that goes down to that level. The flow rate should be at about 4 to 6 liters per minute. Faster than that can cause washout and even barotrauma. The catheter that you drop into the ET tube should be no greater than 70% of the internal diameter of the ET tube lumen to make sure that there's not air trapping and barotrauma. The alternative methods that can be used include using CPAP on the ventilator with O2 flowing at 100% or 100% O2 through a flow-inflating resuscitation bag with a functioning PEEP valve. This is typically done in children. You uncover the thorax and the abdomen to look for any respiratory movements. You abort the test if they breathe, for obvious reasons. If the blood pressure drops to a systolic less than 100 or MAP less than 75 in adults or less than a fifth percentile in children. If there's a progressive decrease in the O2 sat to less than 85% or if there's a cardiac arrhythmia with hemodynamic instability and obtain an ABG right before reconnecting the ventilator if you can or as you're doing that. If they do get hypoxic, you can retry the procedure with some of the alternative methods I just mentioned. If there is no respiratory drive observed, you obtain an ABG after about 10 minutes. You can send it along the way at five or eight minutes also in case they decompensate later on your ABG values along the way may be satisfying the criteria. If they had no respiratory movements and the PCO2 is at least 60 and 20 above the baseline, especially in patients with an elevated baseline CO2 level, and the pH is less than 7.3, that's new, the apnea test is positive. So you have not just the hypercarbia but the acidosis that's a stimulus to breathe. If the test was inconclusive, let's say you get to a PCO2 of 59, but the patient was stable during testing, you can repeat the test for longer, but you have to again adequately pre-oxygenate the patient and reestablish normal apnea and normal pH. What about CO2 retainers? Well, if you know what their baseline PCO2 is, that is the level that you want to target as your starting level. And you have to get 20 points above that for your PCO2 goal. It's the same pH goal of less than 7.3, but a higher PCO2 goal. If you have a patient with suspected chronic CO2 retention, but you don't know their baseline PCO2 level, then you try to estimate it if you can. You still perform the test and have to get to the pre-specified numbers, but you have to get an ancillary test in that situation as well. After apnea testing, you obviously reconnect the ventilator, but I also recommend gently hyperventilating the patient to correct the respiratory acidosis that you caused. The whole point of the test is to cause a respiratory acidosis so that you can trigger the medulla to breathe if it is working. But that acidosis may cause the patient to get hypotensive, and so you want to try to reestablish a normal acid-base status as soon as you can, but gently hyperventilate them because the alveoli may be de-recruited during the test and there's risk for marrow trauma. Additional complications of the apnea test include hypotension, which typically occurs when there's inadequate pre-oxygenation. Tension pneumothorax and cardiac arrest have been reported, but are both fortunately quite rare. There is now guidance regarding apnea testing on ECMO. Pre-oxygenating the patient again through the membrane lung is important, adjusting the sweep gas flow rate, and making sure that you're checking the appropriate spots for the ABGs, especially in patients on VA ECMO. It should be from both the distal arterial line and at the ECMO circuit post-oxygenator sites, and both ABGs need to be consistent with the levels. Ancillary testing is not required. Brain death is a clinical diagnosis. Even if you know you're going to have to use ancillary testing, you still, again, perform all aspects of the clinical testing you can, and if there's any signs of brain death, you don't get the ancillary testing. The preferred tests include nuclear scintigraphy, a four-vessel catheter angiogram, and transcranial Doppler. Please note that EEG is no longer acceptable in the 2023 guidelines, and CTA is still not an approved test either. Indications for ancillary testing include injuries such as fractures to the C-spine or skull base or the orbits or face, inability to complete the apnea test safely, neurological exam findings that are difficult to interpret and may be cerebrally mediated, or metabolic derangements that are unable to be adequately corrected. I'll say it one more time. Even when you know you're going to need an ancillary test, you still test everything you can on the clinical examination, and if anything is positive, the patient is not brain dead. The gold standard is considered catheter angiography, where you give direct injection under pressure in the arterial system, and you should see the flow arrest at the point of entry in the dura. I'll show a video of what this looks like. This is a dynamic angiogram where you can see the flow coming up in the internal carotid and it just stops. You do feel the extracranial circulation, of course, because that is still intact. Nuclear medicine scintigraphy, there should be an absence of intracranial perfusion, seen as a lack of uptake of tracer. Neurogenic agents are preferred over lipophobic because they'll go into metabolically active brain tissue. Given the persistent extracranial circulation, you can see the hollow skull sign, the empty light bulb sign, and the hot nose sign. So this is a patient with both AP and lateral views, so that you can see the brain stem and see that there's no intracranial uptake of tracer. This is consistent with brain death. Transcranial Doppler is approved in adults only. You need to have bilateral anterior and posterior evaluations, two examinations, 30 minutes apart. And what you're looking for is not a loss of signal, but signal that is present with sharp systolic spikes and oscillating flow, where the flow goes to zero or negative numbers in diastole. And this is what it'll look like. You can see that here in diastole, it goes to negative numbers. That means the intracranial pressure exceeds the mean arterial pressure. There's an EEG in brain death. This is not used as a valid ancillary test anymore. However, you may have patients on EEG monitoring that develop this pattern. You can see that this is just EKG artifact on this patient. Otherwise, it is flat. And then you might say, OK, this patient may be brain dead now, and we need to do an evaluation. But this is not an acceptable ancillary test. Again, CTA and, for that matter, MRA are not validated tests yet. We are working on trying to validate those. The time of death is when the PCO2 and pH reach the target values as reported by the lab. Or if an ancillary test was required, it's the time it was officially signed and finalized by the attending physician. And federal and state law require that someone on the team contact an OPO following determination of brain death. Hopefully, that's done when you have a patient that you have a known neurological catastrophe, whether or not they're brain dead. All right. Some special considerations. Consent. Consent has never been required for a brain death evaluation or apnea test. And we continue that trend in our new guidelines. Unless it's stipulated by the institution's policy or state laws, you do not need to obtain a consent before doing a brain death evaluation. How about family observation? It can be very powerful for families to see the entire brain death evaluation, including the apnea test. So it's encouraged to inform families that they may observe this and that there may be reflexive movements that come from the spinal cord and that these do not preclude a determination of brain death. How about families that are unaccepting of the diagnosis? Well, we ask that there be a reasonable accommodation for those patients, but for a limited period of time before discontinuing organ support. Remember, we don't use the words life support in a patient who is brain dead. How about pregnant persons? Well, we said in the guidelines that pregnant persons can still be considered for brain death determination. You need to involve people from maternal fetal medicine to make sure that the performance of the examination and evaluation are safe for the unborn fetus and consider whether ancillary testing may be required so that you don't harm the fetus if it's potentially viable. Neuroendocrine function can be preserved in some patients with brain death. This may be due to renal impairment or simply due to variable circulation to the posterior pituitary. And so the presence of neuroendocrine function does not preclude a diagnosis of brain death. As we spoke about in the beginning, you can have a primary posterior fossa injury that can look like brain death, but you have to demonstrate by a CT or MRI that there's catastrophic supertentorial injury as well. And without that, you cannot feel comfortable that the condition is completely permanent. I always recommend using a checklist. This is a checklist that was used in the World Brain Death Project back in 2020. There is a new checklist that's available through the new AAN guidelines. We recommend that you use a checklist every single time for the prerequisites, for the clinical examination, making sure that you've done every aspect of them that you can, for the apnea testing as well, and then for ancillary testing if required. I've done literally hundreds of brain death evaluations, and I still, every time, bring a checklist, not because anything I'm testing is that complicated to do, but I just don't want to forget or miss anything, and so there's no shame in bringing in a checklist every time you do this. Finally, what are we doing to improve the field? So there are educational and training endeavors like what you're doing right now. There's online training and certification through the Neurocritical Care Society. There are going to be new Neurocritical Care Society in-person training courses, such as one that we put on in the UAE for the last two years and trained over 500 clinicians in that part of the world. There's simulation training, which is a great place to practice, having brain death champions at each hospital, people who do this a lot and are able to train other people, and again, the brain death toolkit is available through the Neurocritical Care Society. We're lobbying the Joint Commission to mandate that hospitals have up-to-date policies that are consistent with the new guidelines, and we've even started retrospective and prospective databases for adults and pediatrics. The adult one is run out of Boston University, my institution, and my friend Matt Kirshen is running one out of Children's Hospital of Pennsylvania for pediatrics. So in conclusion, always use a meticulous, organized approach, and when in doubt, err on the side of not declaring brain death or death by neurologic criteria. Ancillary testing is not a substitute for the clinical exam. You always test everything you can when you can. There's new guidance available for ECMO, hypothermia, pregnancy, and posterior fossa injuries and other things. EEG and CTA are not acceptable ancillary tests, and more science is on the way. So I hope that you've enjoyed this talk, and I'll look forward to answering any questions you might have at the end. Thank you very much.

brain death examinations

Dr. David Greer

2023 guidelines

intracranial pressure

cerebral perfusion

ancillary testing

clinical evaluation

apnea testing