"Brain Death Examination" by David Urion, MD and Robert Tasker, MBBS, MD for OPENPediatrics

Brain Death Examination by Dr. David Urion and Dr. Robert Tasker Healthcare workers in all healthcare settings should always adhere to the latest World Health Organization guidelines on hand hygiene and barrier precautions, before and after contact with a patient, bodily fluids, or patient surroundings. For more information, please watch our video entitled Hand Hygiene Introduction Hello. My name is Robert Tasker. I’m the chief of the NeuroCritical Care Program. This is David Urion And I’m the director of the residency programs in child neurology and neurodevelopmental disabilities and one of the physicians that serves on the neurology critical care consultation team here at Children’s Hospital Boston What we’re going to do today is demonstrate the brain death examination in this 7-year-old boy. Typically, we would do this examination as a pair. It’s important that the neurological examination is done by two different individuals The apnea test can be done by the same person The clinical aspects of the brain death examination are fundamentally the neurologic examination It’s targeted at two particular issues. One is the investigation of coma. And the other is the investigation of brain stem reflexes For the diagnosis of brain death to be made, we would expect that there would be no discernible clinical response that could be attributed to the cortex– that is profound coma– and no discernible responses to interrogating the brain stem through a variety reflexes that we’ll demonstrate Certain conditions, however, need to be met before one could even consider doing this examination. These patients must have a history of traumatic, anoxic, or metabolic brain injury and a progression of that injury over a period of time that could explain the events we are investigating We need to make certain that the patient meets certain parameters, in terms of blood pressure, oxygenation, temperature, and also the absence of any kind of sedating or intoxicating compounds, chemicals, or drugs and the absence of any neuromuscular blocking agents. In any of those instances, we cannot proceed ahead with this investigation All institutions have a set of checklists that they use, in terms of making the determination And we’d encourage you to use that at the bedside to make certain that nothing gets left out and that you proceed in an orderly fashion with the examination. We’ll refer to the set of guidelines that are used as practice parameters here at Children’s Hospital Equipment You will need the following equipment to perform the procedure- reflex hammer, flashlight, cotton-tipped swab, tongue depressor, 60-milliliter syringe, kidney basin, ice cold water, towel roll, arterial blood gas, oxygen source, T-piece, suction catheter Investigation of Coma The first thing we’ll do is examine the patient and see that in point of fact, as we look up here, his heart rate is 110. His blood pressure is 89 to 85 over the 50s. And his oxygenation is at 100% by pulse oximeter That’s all of the metabolic conditions And his temperature has also been demonstrated to be above 36 degrees would be present so that we can proceed with this examination And you’ll have to take our word for it that we’ve interrogated the chart and made certain that there is no explanatory findings of sedating medications, neuromuscular blocking agents, or things of that nature First thing we would do is to see if we can discern any response from the patient at all We’d say, “Hhello, hello, hello, hello young man.” In the absence of that, we’d then

see if more vigorous stimulation would provoke any kind of response from him at all. In the presence of decorticate or decerebrate posturing, we know, then, that parts of the nervous system are still intact. And therefore, the diagnosis of brain death can’t be made It’s important to remember, however, that there are certain automatic responses that don’t constitute anything from the brain itself For example, a so-called triple flexion response– flexion at hip, knee, and ankle– is an involuntary spinal response and doesn’t constitute any kind of a meaningful response from the brain itself And so, in this instance, the first thing we would do is a moderately painful stimulus– for example, here at the toes. Any other number of things can be used to generate a painful stimulus. You can put your reflex hammer in between the toes, holding onto them and twisting like this. We then look to see if there’s any autonomic response. And we see that, while I’m doing this, his heart rate is completely invariant and making no change at all Finally, we’d lift back his eyelids. And we’d look to see if there’s any pupillary response to this at all– again, an autonomic nervous system change that might suggest intactness of certain parts of the thalamocortical connections And in this instance, there’s none Painful Toe Stimulus A normal response to the application of a painful stimulus to the toes is that the patient should withdraw his or her foot, as seen here An abnormal response is when a patient does not withdraw his or her foot, as demonstrated here, nor does he or she demonstrate any autonomic or pupillary response to the stimulus Similarly, we can grab the nail bed and squeeze here. Again, seeing if there’s any kind of pupillary response in our patient. And again– looking for any kind of autonomic nervous system response or voluntary motor response And again, we see none Painful Nail Bed Stimulus A normal response to the application of strong pressure, to any of the nail beds, will be that the patient should withdraw his or her hand, as seen here. An abnormal response is when a patient does not withdraw his or her hand nor does he or she demonstrate any autonomic or pupillary response to the stimulus Investigation of Brain Stem Reflexes Next, we would interrogate the brain stem And the first thing we would do is to see if there is any pupillary response. So the pupils, at this point, are mid-position, fixed, and dilated with no response to light Pupillary Reflex With a normal and intact pupillary reflex, you will observe that the patient’s pupils are mid-position and constrict in response to bright light. An abnormal pupillary reflex will be demonstrated by pupils that are mid-position, often dilated, and do not constrict in response to bright light. It should be noted that certain conditions can make it difficult to assess the pupillary reflex, including preexisting pupillary abnormalities, such as coloboma, topical administration of certain medications to the eye, such as atropine or phenylephrine trauma to the eye Finding that there was no pupillary response, the next thing we would investigate is to see if there’s a corneal response. We would do this by getting some form of a cotton tip– easiest if you pull it just a little bit so we have a small tuft out here– and then applying it to the side of the cornea like this– see if there’s any kind of an aversive response– blink, anything that suggests intactness of this sensory stimulus. And again, we see, on both sides here– no response Corneal Reflex With the normal and intact corneal reflex, you will observe that the eye will blink when you touch a cotton swab to the cornea. An abnormal corneal reflex will be demonstrated by an absence of blink when a cotton swab is applied to the cornea After this, we would do oculocephalic maneuvers That is, we look to see if the eyes can maintain themselves in an attempt midline while I turn the head. So we would never do this examination in anybody who we anticipate, or might be worried, has a cervical spine injury. But

having looked at the chart, we know that this young man doesn’t And so, we would turn his head smartly to one side. And see if, in fact, there’s an attempt to get the eyes back to midline. And we would then do it to the other side. And again, there is no such response Oculocephalic Reflex This is sometimes called the doll’s eye reflex With a normal and intact oculocephalic reflex, you will observe that, when you turn the patient’s head quickly to one side, the eyes will move to remain fixated on one position in space In patients with an abnormal oculocephalic reflex, you will observe that, when you turn the patient’s head quickly to one side, the eyes will remain mid-position It should be noted that this reflex can be difficult to assess when there is significant orbital edema, impairing the ability of the examiner to open the eyes, or with significant conjunctival edema, impairing the ability of the eyes to move appropriately We would next try to stimulate this through caloric testing or oculovestibular reflexes And for that, you need to have some preparation The head of the bed needs to be at roughly 30 degrees so we can have the semicircular canals orthogonal to gravity. It’s always a good idea, since we’re about to put water into the bed itself, to put a towel under here to catch what might flow out of my basin We then fill this basin with ice water. And we would take, into a syringe, 50 ccs of ice cold water, a very profound stimulus of the oculovestibular network. Before we go ahead any further, we would take an otoscope and examine the ear to make certain, first of all, that there is no wax blocking the pathways so that we, in fact, really are going to stimulate the tympanic membrane and also make certain that there’s no other pathology there that would make us not want to do this test So I’ll investigate on this side. And then, just so I have to climb around the desk, Dr Tasker, to look in the other side to make certain that the tympanic membranes are intact and visible. That being the case, we would then go ahead And I’ll ask Dr. Tasker to hold back his eyelids so we can watch. We’ll position the basin just behind the ear, like this. And then, we would insert the tubing. You can make this from any kind of an IV tubing, just removing the needle. And we would then, as rapidly as we can, instill 50 ccs of ice water into this space Now, what we’re looking for is half of what would be usual caloric nystagmus. Remember that nystagmus is named after its fast phase,: coldalled- opposite, warm- same, since the fast phase is the cortical reset. And we’ve already demonstrated that there are no cortical responses. We’d be looking for the brain stem half of this response, which, in this instance, would be the eyes turning toward the cold water stimulus. And we would put in these 50 ccs and wait roughly 90 seconds to 120 seconds and see that there’s no response We’d then come around and do the same thing on the other ear, again, making certain that the eyes begin at midline. And we would rapidly install 50 ccs of ice cold water into the ear and look for any response, waiting for a period of time. And again, we see none Oculovestibular Reflex With the normal and intact oculovestibular reflex, when you instill cold water into the otic canal, you will observe that the eyes turn quickly away from the cold water stimulus and, then, turn slowly toward the cold water stimulus in a repetitive manner. Therefore, if you instill cold water into the right ear, the fast phase of eye movement will be toward the left side and the slow phase of movement will be toward the right side. This is a normal, physiologic response, known as nystagmus After instilling cold water into the ear, you may need to wait 90 to 120 seconds to observe for any response For patients in which there is a lack of cortical response, based on earlier tests, the brain

stem may still be intact. When you instill cold water into the otic canal, if the brain stem is still intact, you will observe the eyes turn slowly toward the cold water stimulus Therefore, if you instill cold water into the right ear, the eyes will turn slowly toward the right side. After instilling cold water into the ear, you may need to wait 90 to 120 seconds to observe for any response If the brain stem of the patient is not intact, when you instill cold water into the otic canal, you will observe that the eyes will not turn toward the cold water stimulus. Therefore, if you instill cold water into the right ear, the eyes will stay mid-position. After instilling cold water into the ear, you may need to wait 90 to 120 seconds to observe for any response before concluding that there is no response Remember that cerumen in the otic canal will prevent the cold water from reaching the tympanic membrane. And thus, you will not be able to assess this reflex The last part of the examination would be to examine the lower brain stem by looking for any kind of oropharyngeal response. We might do this by suctioning the patient or, alternatively, taking a tongue blade or a cotton swab, like this, and inserting it deep into the back of the throat. We’d be looking here for any kind of palatal elevation or response in any of the musculature in the retropharyngeal area. And we see that there’s none Pharyngeal Reflex With a normal and intact pharyngeal reflex, when you insert a tongue blade deep into the back of the patient’s throat, you will see that the palate will elevate. In patients with an abnormal pharyngeal reflex, when you insert a tongue blade deep into the back of the patient’s throat, you will see no response by the musculature in the retropharyngeal area Clinical Pearl Alternative Pharyngeal Reflex Another way to investigate the pharyngeal reflex is to perform stimulation of the carina Some providers feel that patients who have been intubated for a long period of time may have a pharynx that becomes habituated to stimulation because of the continuous presence of the endotracheal tube. Stimulation of the carina can be accomplished by suctioning the endotracheal tube and looking for the patient to cough In a patient with normal pharyngeal reflex, you will observe that the patient coughs in response to stimulation of the carina. In patients with an abnormal pharyngeal reflex, you will observe an absence of coughing in response to such stimulation We’ve demonstrated that there are no discernible brain stem reflexes or responses in this individual In the presence, then, of these elements of neurologic examination– that is, no evidence of any cortical or thalamocortical responses and no evidence of any brain stem reflexes or responses– we can, then, make the determination that the first examination has shown no meaningful cerebral responses. And we would then repeat this examination, separated by time Point of Clarification Please note that the requirements for time intervals between exams vary, depending on the age of the patient and on clinical practices of an individual hospital. You will want to refer to your hospital guidelines for specific details Apnea Test Point of Clarification The apnea test should only be performed following the second clinical brain death examination and only if the results of both exams suggest that the patient has met the criteria for brain death At this stage, we would now want to do the apnea test. Under normal circumstances, the child would have had their mechanical ventilation altered so the carbon dioxide was at around 40 millimeters of mercury. And we would have pre-oxygenated for at least 10 minutes with 100% oxygen via the ventilator and have a blood gas to show that our carbon dioxide was around 40 millimeters of mercury We then proceed to the apnea test. And there are a couple of ways of doing this. We need to have the child’s chest exposed so that we can actually see any breathing movements And then, we want to try and maintain oxygenation during the procedure After disconnecting the child from the ventilator, we can use a T-piece, connected to the ventilator,

with at least 10 meters liters per minute flow through that. When we disconnect the child– using one of these two procedures–, we’re then going to make sure that the oxygen saturation stays above 85% and that the blood pressure stays above the fifth percentile for age. And in this child, we’ll take it to be 75 millimeters of mercury And we need to observe the child for a period of five to 10 minutes. And during that time, we would hope that the carbon dioxide would rise by at least 20 millimeters of mercury If at any time, the saturation falls below 85 or the blood pressure falls below our predetermined lower limits, we’re going to discontinue the test, connect the child back up to the ventilator And we will have to try again some other time In this instance, let’s just assume that we’ve not seen any breathing for five to 10 minutes At the termination of the test, we would take another blood gas, connect the child up back to the ventilator, and wait for the result of the gas. If that showed a 20-millimeter rise, and it was above 60 millimeters of mercury, then we can say that the child has not breathed to that stimulus Clinical Pearl Please note brain death should never be diagnosed at a PaCO2 level less than 60 millimeters mercury, even if the rise in PaCO2 has been 20 millimeters mercury or more. There have been case reports in the literature of children breathing at higher PaCO2 levels. Therefore, some experts have advocated that the threshold should be raised even higher than a PaCO2 level of 60 millimeters mercury. You will need to follow the guidelines set forth in your institution Please also note that a properly done first apnea test will virtually guarantee a positive second apnea test because the rise in PaCO2 levels may likely precipitate brain stem herniation, if this has not already occurred in the patient Ancillary Tests It’s important to remember that there are ancillary tests that can be used to assist you in this diagnosis. But they are not essential nor central elements of the examination or evaluation. These can include an electroencephalogram, looking for electrocerebral silence, or these can be a PET scan or SPECT scan that might look for no flow states into the brain itself That is, the absence of any demonstrable blood flow. It is important, however, to emphasize that these are ancillary tests and not required for the central elements of diagnosis of brain death That concludes our video on

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