Transcript
Speaker: Welcome to Critical Matters, a sound critical care podcast covering a broad range of topics related to the practice of intensive care medicine.
Speaker: And now, your host, Dr. Sergio Zanotti.
Speaker: Death is universal.
Speaker: It is one of the few constants throughout human history.
Speaker: For a long time, death has been understood as the cessation of cardiopulmonary function.
Speaker: With the advent of mechanical ventilation and life support in the ICU, the concept of brain death has emerged.
Speaker: Today, we understand brain death as death of the individual due to irreversible loss of function to the entire brain.
Speaker: The determination of brain death is still fraught with this understanding both from clinicians and from the lay public.
Speaker: Today we will discuss the neurologic criteria for determining death in adults.
Speaker: We will talk about brain death or death by neurologic criteria.
Speaker: Our guest is Dr. Fred Rincon, a repeat guest for the podcast.
Speaker: Dr. Rincon is Associate Professor of Neurology and Neurological Surgery in the Division of Neurotrauma and Critical Care at the Department of Neurological Surgery at Thomas Jefferson University in Philadelphia.
Speaker: He is board certified in internal medicine and critical care, neurology, vascular neurology, and neurocritical care.
Speaker: He's a fellow of the American College of Physicians, the American College of Chest Physicians, and the American Heart Association, and a member of the Society of Critical Care Medicine, Society of Neurocritical Care, and the American Academy of Neurology.
Speaker: Fred, welcome back to Critical Matters.
Speaker: It's my pleasure, Sergio.
Speaker: Thank you for having me here.
Speaker: So last time you were here a little bit over a year ago, we talked about neuroprognostication in patients who underwent targeted therapeutic hypothermia after cardiac arrest.
Speaker: Today, I think we're going to talk about a situation that might arise in this patient, but it's much more common in other situations, which is brain death or death by neurologic criteria.
Speaker: So I think that a good place to start would be to maybe provide us a little bit of a historical perspective.
Speaker: As I mentioned in the intro, we have traditionally understood death as being the cessation of cardiopulmonary function.
Speaker: But really, in the 20th century, with the emergence of critical care and life support, this concept of brain death emerges.
Speaker: Can you tell us a little bit about the history of this?
Speaker: When did this happen, Fred?
Speaker: Fred?
Speaker: So traditionally, we were used to the concept of death on the basis of cardiopulmonary failure.
Speaker: And that's sort of like, you know, it's sort of like, you know, when you look at this philosophically and medically, you know, you start reading all these reports and textbooks, you know, sort of like the cessation of pulse and cardiac function.
Speaker: and respirations was the sort of like indicator of death and the coming of death.
Speaker: And that's how we define it classically.
Speaker: But around 1960, physicians throughout the world, including the United States,
Speaker: By the way, the first ones that describe this concept were the French.
Speaker: They started looking at these patients that had catastrophic brain injury and they ended up on mechanical ventilation for a while.
Speaker: So it sort of became a phenomenon around 1968 when the first reports started to come in the literature.
Speaker: If you look at the first reports in France, they described this as coma de passe or past coma, something like that.
Speaker: So there were all these patients with brain injury that didn't have any brain activity, no brainstem reflexes, no consciousness.
Speaker: They were pretty much in a coma attached to mechanical ventilation and artificial life support.
Speaker: They start questioning, you know, what are we going to do with these patients?
Speaker: You know, they're just like, you know, filling our words and our rooms.
Speaker: And that's when the first sort of like concepts start to emerge about death by neurological criteria.
Speaker: And then they start doing all these electrophysiological studies that showed specific pattern that we see when we request continuous EEGs in these patients.
Speaker: This is this
Speaker: electro, physiological silence, sort of like the description of it.
Speaker: And then they start sort of questioning if they could use or develop a concept of death on the basis of cessation of whole brain function.
Speaker: And that's what led to Harvard investigators to start gathering information about the natural course of this condition.
Speaker: And on the basis of that, the United States started to look in more detail and assemble a group of experts and investigators and try to look at this more in detail and to provide more definitions about what needed to be done in order to arrive to a conclusion of that on the neurological criteria.
Speaker: And that's what you see in the 1970s, sort of the first guideline in the United States by the Harvard Group.
Speaker: And then finally, the UDDA, or the Uniform Determination of Death Act, which was commissioned by the president in the late 70s and then in 1981, what defined death in the United States jurisdiction on the basis of both cardiac and neurological criteria.
Speaker: So, you know, basically what the UDDA says is that the expertise and the way that you arrive to this definition of death and the neurological criteria is on the provider, on the physician's side.
Speaker: It didn't tell how to do it or, you know, or...
Speaker: or the specific criteria that needed to be considered, it just said, you know, that it needed to be done by the providers themselves.
Speaker: And we arrived to a definition, it's sort of like a determination of what needed to be done to arrive to that conclusion.
Speaker: It was basically a very simple thing, you know, had catastrophic brain injury, you know, followed by, you know,
Speaker: a comatose state and absence of brainstem reflexes.
Speaker: And then we sort of like define more how to approach that disease state over the following 20 years.
Speaker: And that's sort of like the historic snapshot, right, of how we arrive to this conclusion and to this syndrome that we see nowadays after catastrophic brain injury in the intensive care unit.
Speaker: And I think it's important because this is obviously not a
Speaker: old history, but considering relatively new with the advent of the development of ICUs.
Speaker: But like you said, just to recap, the first guidelines really came in the United States from the group in Harvard in 1968 and legislation at a federal level.
Speaker: with the Uniform Determination of Death Act in 1991 established that you could be pronounced dead either by cardiopulmonary criteria or by neurologic criteria.
Speaker: But what the legislation stated, like you said, Fred, was that that was based on a medical standard.
Speaker: So they really left the court or the legislators left the medical standard to be determined by clinicians and by societies.
Speaker: So I think that, as you mentioned earlier, there are some
Speaker: classical or simple elements that have to be part of that initial determination.
Speaker: Why don't we dive a little bit more into the determination of brain death?
Speaker: And as you mentioned, you talked about the clinical evaluation of coma and some prerequisites.
Speaker: the absence of brainstem reflexes, and then apnea testing.
Speaker: And tell us how, from the guidelines that were published in 1995 forward, how do we really think at the bedside, what should be the first steps that we should take as intensivists or neurointensivists in determining if a patient is brain dead?
Speaker: Yes, so that's very important.
Speaker: I think what you mentioned about how
Speaker: the attorneys or the judges sort of like left this to the providers, right?
Speaker: How we were going to define this syndrome is extremely important because
Speaker: you know, for future discussions, and it's very important for me to say this up front, is that, you know, we arrived at these conclusions on the basis of expertise, not on the basis of empiric data.
Speaker: So we basically determine certain things which I will mention, you know, what are the prerequisites for the clinical evaluation, you know, what are the sort of like guidelines in the United States.
Speaker: And by the way, when I say guidelines in this jurisdiction, that's an extremely important thing.
Speaker: because the American Academy of Neurology has these criteria and that's the criteria that we use at the point of care at the bedside.
Speaker: It's different, like if you cross borders, it's different in Europe, it's different in Asia, and it's very different, for example, in Latin America.
Speaker: But most of these jurisdictions sort of like adopt the same things that we interpret here in the United States, sort of like the American Academy of Neurology.
Speaker: You come to a question about is this patient brain dead when you have somebody with catastrophic brain injury.
Speaker: So like the most important thing is that you identify that there is a massive injury to the brain that would not be compatible with life otherwise.
Speaker: And then you start examining the patient.
Speaker: And the first thing that you have to document is absence of consciousness.
Speaker: So is the patient comatose or not?
Speaker: And if the patient is in a coma, then you can see you build your case by examining the patient.
Speaker: And what you do when you're examining the patient is, by the way, examining primarily the brainstem because there's no way of documenting, you know,
Speaker: you know, is the patient thinking, you know, unless you fight or is the patient experiencing sensations unless you are a seasoned, you know, examiner, neurologist that can pick up, for example, pitfalls, you know, like, for example, a patient with a, you know,
Speaker: locked-in syndrome, how to communicate with a patient that looks comatose that is not in reality comatose.
Speaker: But that's part of another discussion.
Speaker: So the second thing is to document total absence of brainstem reflexes.
Speaker: And you have to do a thorough neurological exam at this level.
Speaker: So you start with the pupils, you start with the reaction to corneal stimulation, you look at the absence of movements of the eyes with stimulation by either movement
Speaker: of the head if the patient doesn't have neck injury or by stimulation with caloric testing of the vestibular center.
Speaker: So sort of what we call cold caloric.
Speaker: And you continue going down the different levels of the brainstem.
Speaker: Then you check for the gag and the cough.
Speaker: And then finally, you have to test the lower segments of the medulla so you make sure that there is no movements of the neck or
Speaker: or abnormal posturing when you stimulate different levels.
Speaker: And this is an important aspect of the neurological exam is that you have to examine the patient above and below the foramen magnum.
Speaker: So this is a concept that sometimes doesn't get translated very well.
Speaker: It's what is the reaction with a painful stimulation on a finger or a toe or
Speaker: or a segment lower than the foramen magnum, and what happens when I examine the patient above the foramen magnum, because you have to see absence of total responses with both.
Speaker: So what happens when I stimulate the V1 to V3 painful areas, right?
Speaker: It has to be total absence.
Speaker: Then once you document that there's really no response
Speaker: to your, during your physical exam, and you document there's total absence of brainstem reflexes, then you try to confirm that there's really no
Speaker: response to a stimulation whatsoever and you do this with a apnea test which is a co2 challenge at the bedside.
Speaker: So Fred, before we go to the apnea test, I mean I think I want to dive in a little bit further into this first step which I think is very important and that may be a not as problematic for our neurology and neurocritical care colleagues but maybe something that some of our general critical care
Speaker: colleagues might need a little bit of reminder.
Speaker: So before we go to the apnotist, like I said, I want to dive in a little bit more.
Speaker: So first, could you just enumerate for us some of the prerequisites before we do this exam?
Speaker: So there are certain conditions, obviously, that we must make sure before we start doing this exam, because under certain conditions like heavy anesthetic or neuromuscular blockers, we might have what seems to be an exam consistent with
Speaker: brain death, but that could be problematic.
Speaker: So could you first tell us some of the prerequisites before we even attempt the exam?
Speaker: Yes, that's extremely important.
Speaker: So you have to make sure that there are no confounders during your exam.
Speaker: And the first thing that you make sure is that the patient's blood pressure is, for example, adequate, that the temperature is normal, that the patient is not hypothermic.
Speaker: You document that there is no metabolic disarray.
Speaker: You make sure that
Speaker: the sodium and the glucose are within normal limits, that there are no exposures to sedatives or analgesics that could cloud your neurological exam.
Speaker: In this sense, you need to also make sure that if you have had a patient that has been exposed to a metabolic problem or sedatives or analgesics, that the renal function, for example, and the
Speaker: liver function, are sort of close to normal because otherwise you have to consider half-lives of medications before you end up doing a brain-dead exam.
Speaker: You have to be extremely careful.
Speaker: This is extremely important before you try to determine if somebody's brain-dead is that.
Speaker: All these variables are checked.
Speaker: So we have a checklist, and if you go to the American Academy of Neurology,
Speaker: They provide a checklist that you could use and apply in your protocols.
Speaker: I can give you the link to those papers.
Speaker: And it's very clear, you know, what happens when the patient has been exposed to pentobarbital.
Speaker: What is the level of pentobarbital, for example?
Speaker: that is accepted for a brain dead examination.
Speaker: So all of that is extremely important.
Speaker: Normal oxygenation, a normal CO2 level, and there are some prerequisites, for example, in that case for COPD patients that have chronic respiratory acidosis, for example.
Speaker: So it's just to make sure that your exam is not confounded by anything.
Speaker: And you mentioned drug half-lives.
Speaker: What would be a general guideline
Speaker: in terms of time for how many half-lives would you wait in general with normal renal and hepatic function?
Speaker: It's usually five half-lives, the ones that you need to consider.
Speaker: And that's if your kidneys are normal.
Speaker: So if somebody has renal failure or liver failure, you have to be even more careful.
Speaker: You may need to wait even longer.
Speaker: So, you know, it's...
Speaker: The recommendation by the AN guideline is five half-lives.
Speaker: So at least five half-lives in general.
Speaker: And also you mentioned, like, for example, with penobarbital, you can check actually levels.
Speaker: And I think there are levels that are recommended and will include the document you referred to in the show notes.
Speaker: Also for alcohol, you could measure alcohol levels as well.
Speaker: So these are things that I think just to make sure that there's no confounding effects.
Speaker: I mean, a common...
Speaker: Seeing maybe some of our severe patients with ARDS is the use of neuromuscular blockers.
Speaker: So making sure that those are out of the system, you can do a train of four and you would expect a four out of four stimulation.
Speaker: So all these things, like you said, that are just a part of a checklist to make sure that our exam is not confounded by external factors that are reversible.
Speaker: Correct.
Speaker: I also wanted to dive in a little bit deeper, Fred, in the exam itself because I do think that there are some maybe subtleties that are sometimes missed to the non-neurologist.
Speaker: So you did mention the evaluation of the pupils, I mean reactivity to light, how that happens.
Speaker: Any comments on the oculosephalic reflex?
Speaker: So I think that something that I have noticed is that very often people
Speaker: clinicians who are not neurology trained will only do a horizontal, but they don't do a vertical oculocephalic test.
Speaker: Any comments on that?
Speaker: Yes.
Speaker: So, yeah, sort of the classic testing of horizontal line movements, right?
Speaker: The structures that control the horizontal line movements are primarily located in the pumps, you know, so the PPRF, the parapointing reticular
Speaker: formation and then also the sixth nerve, for example, and then the connection system between that and the third nerve.
Speaker: So that, it's primarily in the palms and in the midbrain.
Speaker: But vertical eye movements are a little different.
Speaker: The third nerve controls and the fourth nerve controls some of those vertical movements, but in reality, the connections are certainly the circuitry, right, that has the control of this stuff, you know,
Speaker: It's sort of like distributing the brainstem in a different way.
Speaker: So vertical eye movements, I think about the tectum, the upper eye movements, and then the lower medulla, they have some connections that go down.
Speaker: So that's what it means, is that you're testing really lower segments of the brainstem.
Speaker: People forget about these networks.
Speaker: They are subcortical.
Speaker: They are not easily testable.
Speaker: And that's why vertical eye movement is important.
Speaker: So basically, you move the head if the patient doesn't have C-spine injury.
Speaker: If there's no evidence of trauma, the spinal cord or the C-spine.
Speaker: So you move the head horizontally and then you do a head tilt maneuver and then you see if there are any vertical eye movements because if the medulla in the lower portion is still alive, right, or that still means that there's still some brain activity and that's what you want to eliminate.
Speaker: And that also applies for the 11th nerve, which is the spinal nerve that has
Speaker: some anatomical distribution that is extra foraminal, meaning it goes down into the spinal cord.
Speaker: You want to make sure that that level, it's not the 12th, right, it's the 11th, the one with the lowest level in the middle, that that level is totally absent.
Speaker: So it would be different, right, if you press on the head, you know, in the supraorbital area, for example, to produce a painful stimulation, and then the patient starts to move the shoulders or the neck in,
Speaker: in an unusual way, that's different, right, if I elicit the same response from a nail crush, because I know, right, the nail crush may be just a spinal cord mediated reflex, whereas if I elicit the same thing about the foramen magnum, I know that there's still some connection between that fifth nerve and the 11 causing this abnormal movement.
Speaker: So this is why, you know, you do,
Speaker: These lower segments of the medulla testing and vertical eye movements are one of them.
Speaker: Excellent.
Speaker: So I think that just to recap some valuable pearls for our audience, making sure that you go through the prerequisites.
Speaker: I mean, use a checklist in terms of drugs, making sure that it's five half-lives or more of any drug that can impact patients.
Speaker: the levels of consciousness, making sure that you examine above and below the poramen magnum in terms of making sure that you are eliminating any type of connection between, I mean, the brain and the rest of the body.
Speaker: And then finally, when you look at ocephalics, making sure that you're testing both for horizontal and vertical ocephalic reflexes, which sometimes can be deceiving in certain lesions.
Speaker: So those are all, I think, things that
Speaker: I'm sure a lot of our clinicians who are not doing this on a regular basis might forget once in a while.
Speaker: So I think very valuable to kind of recap.
Speaker: So once we have confirmed that we have a diagnosis of a devastating injury that's irreversible, we have eliminated any influence of external factors that are reversible.
Speaker: We've gone through our checklist.
Speaker: We did a thorough exam, and that is a
Speaker: consistent with brain death, the next step, like you said, would be to go for the apnea test.
Speaker: So tell us a little more about the apnea testing.
Speaker: So the apnea test in my mind is just a confirmation that there's really no brainstem or deencephalic activity that would elicit a respiration during a challenge of CO2.
Speaker: So CO2 is a very powerful stimulant of the deencephaline.
Speaker: And that's why you breathe even though you don't think you're breathing.
Speaker: And if you elevate the CO2 to a level that is usually considered more than 20 millimeters of mercury, which is not based on any empiric data, by the way.
Speaker: This is just expert opinion.
Speaker: But if you elevate the level substantially and more than 20 millimeters of mercury, you don't see any responses.
Speaker: then you are satisfied with the assumption that there is no brain activity.
Speaker: So that's what confirms this concept of cessation, whole cessation of brain function.
Speaker: the amnia test.
Speaker: And with the guideline and per the law, that's what satisfies the diagnosis of brain death.
Speaker: As long as you have gone through all of these prerequisites, very thorough neuroexam, right?
Speaker: And then finally, the amnia test.
Speaker: For the amnia test, you have to have also some considerations.
Speaker: Your patient has to be normothermic, so you cannot do an amnia test in somebody that is hypothermic, that is resurfacing from
Speaker: hypothermia from cardiac arrest, for example.
Speaker: You have to have a... Or environmental, right?
Speaker: Or environmental hypothermia.
Speaker: Or environmental.
Speaker: Yeah, exactly.
Speaker: You have to rewound the patient.
Speaker: The systole blood pressure, believe it or not, according to the guideline, has to be more than 100 millimeters of mercury.
Speaker: And again, there is no data to support that, but it's biologically accepted that at that level you can still maintain perfusion.
Speaker: to structures in the brain.
Speaker: So that's one of the prerequisites.
Speaker: And then the other prerequisite is that you have to have very good pre-oxygenation.
Speaker: So before we do an amnia test, we usually pre-oxygenate our patients.
Speaker: We put it on FiO2 of 100% for a couple of minutes.
Speaker: And then having a baseline ABG that tells you
Speaker: that the patient oxygenation, usually more than 200 millimeters of mercury is what's recommended to perform anatomy test, because that's what's going to give you an idea if the patient is going to tolerate it or not.
Speaker: It wouldn't make sense to get one of your ARDS patients that has a PAO2-DF2 ratio of less than 100, right?
Speaker: And the patient wouldn't tolerate that.
Speaker: I mean, you will have to stop the test almost immediately because the
Speaker: reserve would be too low.
Speaker: So that's one of the reasons why that number is there.
Speaker: And then finally, you have to have a normal pH status, a normal acid-base status.
Speaker: A couple of things, I mean, Fred, to kind of talk a little bit more about the items you mentioned for the apnea testing.
Speaker: So clearly, I mean, there are patients that we won't be able to do an apnea test.
Speaker: So there are patients who you said who are too hypoxemic to tolerate a PIPA-5 or be off the ventilator, like severe RDS, who would not be candidates for an apnea test.
Speaker: There are patients who become hemodynamically unstable.
Speaker: Those will not be a candidate for an apnea test.
Speaker: So I think that's important to recognize that.
Speaker: An apnea test would be the logical next step in this determination, but sometimes it's not possible.
Speaker: And we'll talk a little bit more about what to do in those cases soon.
Speaker: But let me ask you another question, Fred.
Speaker: What constitutes, so you said a positive apnea test is when the patient fulfills all these criteria, we are able to disconnect them from the ventilator, we observe no breathing, and
Speaker: in a period of 8 to 10 minutes, and when we get a gas, either the PCO2 was over 60 or went by 20 or more above the baseline.
Speaker: And in those cases, we would call the apnea test positive, correct?
Speaker: That's correct.
Speaker: That's what the guideline suggests.
Speaker: And I think that a very important situation is that if we were to do this with a patient,
Speaker: By definition, at this point, that time would dictate the time of death for this patient.
Speaker: So when we filled the death certificate, it would be the time that we completed or proved that the apnea test was positive, which I think is something that sometimes people don't understand, especially with patients who then become organ donors or other things go on later.
Speaker: But let's talk a little bit, Fred, about an aborted apnea test.
Speaker: So when do you stop the apnea test?
Speaker: So when I see respirations, when I see the patient is taking a deep breath, we have recently one here in my institution where minute number five, he took a small breath, so we stopped the amnithesis.
Speaker: So that's one.
Speaker: If you see something that resembles arousal, suddenly the patient opens the eye, something like that, you have to be extremely
Speaker: careful and perhaps seasoned not to stop an amniotest when a patient starts having weird motor responses.
Speaker: And what I'm saying is that there are some spinal cord mediated phenomena that you could see
Speaker: in these patients and it's not related to the patient is waking up or not, it's related to the acid-base status that you are causing.
Speaker: You are basically causing an acidosis.
Speaker: A very quick elevation in CO2 will translate into a very quick lowering of your pH.
Speaker: And that acidosis, sometimes, not every patient, I've seen probably one in 12 years of practice,
Speaker: They may elicit weird muscular abnormalities.
Speaker: And you see that sometimes, you know, these myoclonic movements in patients with metabolic acidosis.
Speaker: So sometimes you could see these weird movements and you really have to be very seasoned, you know, to sort of like discern if this is a muscular response mediated to acidosis or not.
Speaker: You know, my take on apnea tests, right, is that, I'm sorry, on the whole brain death process,
Speaker: pathway, right, is that you really have to be sure.
Speaker: And if you are not sure, it's better to say, I'm aborting this test.
Speaker: If you see something abnormal, you're not comfortable with, right, it's just to better say, you know, I cannot really pronounce this patient because he, you know, had an extensor response.
Speaker: And you cannot really say that it was just final core mediated.
Speaker: It's just better to say, you know, I'm going to stop this.
Speaker: I'm going to continue.
Speaker: I cannot pronounce it.
Speaker: pick an ancillary testing.
Speaker: I think when in doubt, obviously you stop.
Speaker: And I think that it's also another reason why a lot of authors have recommended that when we do these apnea tests, we do not leave the patients hooked up to the ventilator because any movement could trigger a breath and fool you.
Speaker: So usually just having oxygen through a T-piece or just directly into the ET tube is a recommended method.
Speaker: strategy and for the person that is going to pronounce the patient to be present at the bedside making the observations and the determination I think is very important.
Speaker: Exactly.
Speaker: Yeah, no, we usually insert a cannula through the ET tube and we put 100% oxygen through it and patients that don't have any pulmonary abnormalities, they will tolerate that.
Speaker: But yeah, you have to disconnect it from the ventilator for sure.
Speaker: And I think that one of the things that the literature have shown, Fred, and what we discussed earlier is that the basic concept of brain death, the basic tenets of what is required to make that diagnosis are not that controversial.
Speaker: Where there's variability, I think, among the medical community is in the details of how certain things are done or not done, because like you said, we don't have a lot of
Speaker: randomized or prospective studies that have compared these ways of doing things one to another, and there is significant variability.
Speaker: And that's why I think it's important for clinicians not only to know the American Academy of Neurology recommendations, but to understand very thoroughly what is the guidelines or policies at their institution and also how those work with their local state laws, since there's some variations that we might get to later from state to state.
Speaker: Let me ask you another question regarding the apnea testing, which I think is something that a lot of people sometimes struggle with because the concept is easy, but then when you try to implement it, it becomes a little bit more problematic.
Speaker: What about consent, Fred?
Speaker: Do you need to get consent to do an apnea test?
Speaker: Yeah, so that question polarizes a lot of the providers.
Speaker: If you ask the question, do you need consent for an apnea test,
Speaker: It would polarize a group of intensivist providers or people that do this frequently.
Speaker: And the reason for the consent question is because you're going to basically perform a procedure that could
Speaker: actually have some complications during the procedure, right?
Speaker: So if you think about the consent process that we use in our patients that are alive, and by the way, you know, the patient is still alive when we're going to do an amnia test, then requesting permission to do something that could potentially harm the patient, right?
Speaker: The pressure can drop or, you know, something could happen to the patient, you know, he can code during the amnia test,
Speaker: It's very important.
Speaker: So you don't need written consent in my opinion.
Speaker: What you need to do is inform the family that you're gonna do this condition, I'm sorry, this procedure, this testing to document that there is no brain function as your last step
Speaker: to arrive to the conclusion of death and the neurological criterion.
Speaker: And perhaps the most important thing that you need to disclose, right, is not just that there could be complications, but that you're going to be there with a group of people that could actually, you know, take care of the complications, is that the outcome could be that the patient is going to be dead.
Speaker: That's for me the most important part of the disclosure of the whole process is that once I do this and I document that there is an elevation of more than 20 and the CO2 increased substantially and there was no response, is that the patient's gonna be declared dead because the community doesn't understand this concept very well.
Speaker: And if I tell you that sometimes when I have these discussions with families, they are like, okay, that's great, so what is next?
Speaker: And then you're like, well, your family member is going to be pronounced dead.
Speaker: What is next is that he's going to get disconnected from the ventilator and he's going to go to the morgue, right?
Speaker: They don't understand that.
Speaker: And this is why it's so important for you to tell them that the outcome is that they are going to get a documentation that they are dead and therefore everything stops, not just the medical care.
Speaker: Many things will stop once you document the patient is dead.
Speaker: I agree, and I think that a lot of the specifics for the process, if you look at the guidelines that we'll put at the show notes, the checkboxes are there.
Speaker: We all could go through that and make sure that you cover all those things.
Speaker: But part of the difficulty, I think, that arises with these cases, and there's been some very, very publicized cases where families refuse to accept this diagnosis, might be mitigated by how we approach families.
Speaker: And I think that I agree with you, Fred, 100%.
Speaker: Families should be aware of what's going on.
Speaker: What I usually try to do is to explain to them that there are two ways that we pronounce patients dead.
Speaker: One is when their heart and their lungs stop working, which I think most people understand very easily.
Speaker: But I also tell them that the other way is when the brain doesn't work, it also is considered dead.
Speaker: But in the case of this patient in the ICU, the heart and the lung continue because of the machines.
Speaker: So when we suspect that we might be able to tell the families, your loved one has devastating neurological injury from this process.
Speaker: We suspect that this patient, your loved one might be dead by what we called neurologic criteria or be brain dead.
Speaker: We're going to test for that.
Speaker: And I think it's a good lead way into saying we're going to do an apnea test and explain what it is.
Speaker: And it starts, I mean, preparing the family.
Speaker: And I think that the key here is to use a simple,
Speaker: the language as possible and be very clear in terms of what we're doing and what is happening.
Speaker: Like you said, Fred, I think can decrease the role of confusion because these are obviously, especially when they're younger people or unexpected problems, dramatic cases, tensions are very high.
Speaker: The emotions are very high.
Speaker: And I think it can become very confusing for a lot of families.
Speaker: Yeah.
Speaker: So let's say that we are unable to, so actually if we are able to confirm that the apnea test is positive, like we said, at that point based on the current laws that we have, right, and in most states you would document that the patient meets criteria for death by neurologic criteria or for brain death.
Speaker: If you can't do the apnea test, what are other options to try to get to this diagnosis?
Speaker: Yeah, so the concept of brain death is cessation of whole brain function, right?
Speaker: And what you need to understand that this is on the basis of total collapse of serial blood flow.
Speaker: So when you think about brain death as a condition, right, that translates into total cessation of blood flow, then it gives you an idea of what you can do to determine, right, if the patient is dead.
Speaker: So blood flow testing is in my mind one of the ancillary testings of tests that I would always try to get or consider.
Speaker: There are some
Speaker: studies that with electrophysiological testing like EEG, and they were part of the original definition of the syndrome.
Speaker: But in my mind, that is really not recommended nowadays, even though it's still part of the guideline that you could still use EEG.
Speaker: And some jurisdictions use electrophysiology.
Speaker: They continue CDG, SSCPs as part of their ancillary testing battery.
Speaker: In my mind, knowing that brain death and total cessation of brain function on the basis of serial blood flow collapse, then I am always trying to get a blood flow test.
Speaker: And the main ones that we have available nowadays are the nuclear scans with technicium.
Speaker: research, more empiric data suggests that, for example, transcranial dopplers are also very good.
Speaker: And the beauty of TCDs is that it's portable.
Speaker: So the problem that we have in the ICU sometimes is that the patient is too sick to do an amnia test, so we cannot do it.
Speaker: And then it's too sick to be transported to a different setting than the ICU for this blood flow testing.
Speaker: Cerebral angiogram is another one that you could consider, but again, the patient has to be transferred.
Speaker: There is some data on, you know, some reports, for example, using CTA, computed tomography and geography, and even MRAs.
Speaker: I don't think the sensitivity is that great that I would actually recommend CTA or MRAs.
Speaker: I think that
Speaker: Technetium and TCDs have the highest sensitivity.
Speaker: And as I said, it's the portability of TCDs that in my institution and in my practice, I always default to when I cannot do an ancillary test.
Speaker: And I think that – Go ahead.
Speaker: What I was going to say, Fred, is that a lot of our listeners obviously practice in large community hospitals.
Speaker: And I think that expertise with TCD might be more limited to centers that do it a lot.
Speaker: So obviously in the right hands, like you said, it has tremendous advantages, especially that it can go to the patient.
Speaker: But I do suspect that in most hospitals in the United States, probably an angiogram, a nuclear scan, or an EEG is what's most readily available.
Speaker: Would that be a fair statement?
Speaker: Yeah, you're right.
Speaker: And the problem with TCD is also the inter-observer variability.
Speaker: So there are patterns in the TCDs that you need to consider, not
Speaker: showing blood flow is not enough.
Speaker: You have to have a pattern and it's called reverberation of flow.
Speaker: That means that the flow is coming back out of the arteries that go and it has to be in the four vessels.
Speaker: So yes, so you know, TCDs, even though they offer an advantage logistically, they are not that prevalent because of what you're saying.
Speaker: Angiograms, in my mind, perhaps the gold standard, but
Speaker: In my institution, we cannot get angiograms from brain death patients, for example.
Speaker: And I think that one of the things that I noticed is that you used the term ancillary test.
Speaker: For much of the literature in the past, or when you speak with people in practice, you might hear people talk about a confirmatory test.
Speaker: Give me the distinction there, and which is the preferred term these days?
Speaker: I think, you know what, I don't know, Sergio.
Speaker: I think the terms are used interchangeably and ancillary testing.
Speaker: I think it's what the guideline sort of like defines this test as.
Speaker: A confirmatory test, you know, in my mind is the amnio test, you know?
Speaker: That's what confirms at the bedside, you know, that there is no, you know, deencephalic function.
Speaker: And I guess the point I was getting to is that none of these are gold standards, these ancestry tests.
Speaker: And the gold standard really is, as you mentioned, the examination of the patient and the apnea test, right?
Speaker: And these can help you get more data points.
Speaker: But ultimately, like you said, I mean, the reason why I think the guidelines are using or pushing the concept ancillary is because none of these are a gold standard by themselves and that you need to do the other steps.
Speaker: And it's only when you cannot do the apnea test and you want more information to be sure or some, I guess, hospital protocols, they might include these.
Speaker: But again, I mean, like you said, I mean, these are ancillary tests to give you a little more data.
Speaker: Is there ever a role to do more than one test, more than one ancillary test, or you just go with one and the one that you think is most appropriate for your patient and based on your institution's expertise?
Speaker: Yeah, I would just use the one that you have available where you have more experience with.
Speaker: I don't think that you should be doing many ancillary tests at the same time.
Speaker: You will get confused.
Speaker: with the results, you may get false negatives, false positives.
Speaker: I mean, you may be confused.
Speaker: As you were saying, in reality, the gold standard is the clinical exam and the amnia test.
Speaker: And then, by the way, the American Academy of Neurology, it's sort of like the position is that you should try to do everything possible to document this exam or to arrive to the conclusion of death by neurological criteria.
Speaker: with just a clinical exam and the apnea test.
Speaker: Yeah, and I think that, go ahead.
Speaker: Yeah, there are some jurisdictions, perhaps more in Europe or in Latin America, where they require you by law to have the clinical exam, the apnea test, and an ancillary testing.
Speaker: And perhaps you may be working in an institution that requires both, I don't know, because the law,
Speaker: basically says it's up to the provider, right?
Speaker: That means perhaps up to a committee in the institution to define what is your battery of testing that you want to do for a patient to arrive to that conclusion.
Speaker: So in a hospital, you know, even in the United States or in the state, you know, you may be required by law, right?
Speaker: Though I'm not aware that you may require both the clinical, the apnea, and also the ancillary testing.
Speaker: And I think that we mentioned earlier, but I think it's worth repeating for our audience.
Speaker: There really are a couple of levels in terms of what to do.
Speaker: So the law, the federal law in the United States, is
Speaker: allows people to be declared dead based on a neurologic condition, and the law establishes that the criteria for those conditions are based on the medical standard.
Speaker: There are some specific variations in some state laws that allow for some provisions or some exemptions, but basically it's still very similar.
Speaker: And then you have really two more levels of medical knowledge.
Speaker: One is what the guidelines say.
Speaker: And like Fred said, the American Academy of Neurology is really the predominant guideline that people have endorsed.
Speaker: And they very clearly tell you that it's the examination, so the right setting, the examination, and the apnea test, that is all that's needed.
Speaker: If those are conclusive, you can declare somebody brain dead.
Speaker: The ancillary testing is only recommended when you cannot
Speaker: perform a apnea test or it's aborted or the exam is inconclusive because you cannot perform an exam and we'll talk about that in a second.
Speaker: And then finally, I think it's very important for our providers to be familiar with what are the policies and guidelines for their institution and what does the law say at their state.
Speaker: So having practiced in New Jersey, it is very well known that
Speaker: that New Jersey has a very clear exemption based on religious beliefs that allows families to present that, and the patient cannot be declared dead by neurologic criteria.
Speaker: But that's a very specific situation to New Jersey.
Speaker: So I think that I would encourage our listeners to really understand what are the local laws, but also what are the local laws.
Speaker: policies at their institution.
Speaker: Who can do the test?
Speaker: How do they do the test?
Speaker: What is required?
Speaker: So they make sure they comply with all those requirements.
Speaker: Before we move on to some special circumstances, Fred, I wanted to ask you about situations that might mimic brain death that actually we have to be careful with.
Speaker: I'm sure they're very rare, but any situations in particular that come to mind?
Speaker: Yeah, so the ones that we mentioned at the beginning where we want to really be careful, you know, and for which we have a checklist, right?
Speaker: Any metabolic condition, you know, that would cause transient cessation of brain activity.
Speaker: So intoxication with drugs, you know, sort of like the main one that I'm thinking.
Speaker: Exposure to analgesics and sedatives, right?
Speaker: We use a lot of, believe it or not, a lot of pentobarbital for management of ICP in a neurological patient.
Speaker: So, you know, once you give pentobarb a sufficient dose, you will basically, you know, mimic, you know, a brain death exam.
Speaker: Your patient will have no neurological activity whatsoever, and they will have isoelectrical, I'm sorry,
Speaker: Electronegative silence is what I'm saying in the EEG.
Speaker: So all of those are in my mind.
Speaker: And then things,
Speaker: like the locked-in syndrome, which is the one that I always get concerned about, where you will have a patient that looks comatose but is in reality aware.
Speaker: So knowing how to test and examine these patients is extremely important.
Speaker: When I'm examining a comatose patient, I usually open their eyes with my hands and I try to communicate and see if there's any response.
Speaker: Vertical eye movements is the one that I'm looking for.
Speaker: But again, these patients usually have very localized injuries in the brainstem.
Speaker: So you will see them in the imaging, that there's really no major supratentorial brain injury that could explain the exam.
Speaker: So you have to be a little more concerned.
Speaker: But those are primarily the ones, intoxications and the Loctin syndrome.
Speaker: Excellent.
Speaker: So I think that as we start wrapping up, I guess the last topic that I wanted to touch about brain death is the special circumstances that are becoming more prevalent as we evolve and the way we provide critical care.
Speaker: So the two specific that I wanted to ask you, you can just give us some very targeted comments on patients who are post-cardiac arrest who get targeted temperature management for anoxic brain injury and patients who are on ECMO or extracorporeal membrane oxygenation.
Speaker: Yeah, so for the first cohort, the patient post-ETM after cardiac arrest, you know, you have to be more careful because hypothermia has changed, you know, the way that these patients look like.
Speaker: And the prognosis also has changed a lot with exposure to hypothermia post-cardic arrest.
Speaker: Now, in my practice, right, we sort of like know it once we see it.
Speaker: We have a patient with cardiac arrest with a prolonged time to ROSC with an imaging that shows already some serial edema, which may be substantial, a lot of effacement in the sulci and the gray, white matter areas.
Speaker: And then once they start resurfacing from hypothermia to normal temperatures, then when you're examining them serially, you start thinking, I don't think this is going in the right direction.
Speaker: This patient is perhaps dead.
Speaker: So I usually wait the first 24 hours of hypothermia.
Speaker: My patient has been hypothermic down to 33.
Speaker: If you are at 36, it's a little different.
Speaker: You can actually move faster.
Speaker: but I usually wait a couple of hours after I get the patient back to a normal thermic range.
Speaker: I exclude with the checklist any possibility of exposure to sedatives or organ dysfunctions that could preclude the exam of brain death.
Speaker: And then after I go through the checklist, I examine the patient in a thorough way.
Speaker: But again, it's sort of like this,
Speaker: feeling that you have that you know the patient is not going to turn out well.
Speaker: I think it's something with the experience.
Speaker: But I wouldn't try to do an exam up front.
Speaker: Most of the patients that have cardiac arrest that come to the emergency department, they look brain dead.
Speaker: They have no brain activity whatsoever.
Speaker: So unless I know the patient has been down for a while and they're just trying to resuscitate somebody that looks dead from the beginning, I probably will not attempt a brain dead exam up front.
Speaker: I will let him go through the whole process and then do my neuro-pagnostication after they're re-warm.
Speaker: For the ECMO patient, it's a little bit more difficult because they have total artificial
Speaker: circulation.
Speaker: And there's been some attempts that sort of mimicking the amnia test with CO2 challenges by infusing CO2 in these patients.
Speaker: But in reality, I think that the blood flow studies are probably the way of going around the normal pathway in these patients.
Speaker: You cannot examine these patients on
Speaker: on ECMO because you are not gonna have the opportunity of performing a conventional amnia testing.
Speaker: So can you infuse CO2 via the ECMO machine and sort of like mimic or simulate the challenge?
Speaker: And the answer is there, a couple of reports.
Speaker: I think the one that I can think about is from the major clinic that try to do this and sort of like, but not every institution has that experience or availability.
Speaker: What we have done at my institution is TCDs.
Speaker: So, transpinal dopplers can help because they are portable.
Speaker: You don't need to get these patients with all this machinery down to the angiosuite or the nuclear suite.
Speaker: And you can do a
Speaker: a quick assessment of a blow flow with those patients.
Speaker: And as I said, you have to look for the pattern, which is reverberation in the four vessels.
Speaker: So it's interesting, like you said, I mean, with the post-cardiac arrest patients who underwent targeted temperature management, obviously it's about making sure that the timing of the assessment is appropriate.
Speaker: We had a whole discussion on neuroprognostication in this population with you a year ago, so I'll make sure that I link that episode to the podcast.
Speaker: show notes if people are interested.
Speaker: And with ECMO, I think the challenge, obviously, is the apnea test.
Speaker: There are some reports, like you mentioned, Fred, where people have used the ECMO machinery in the sweep to titrate or simulate the apnea test and see if that stimulates bleeding.
Speaker: But it seems that this is a case where an ancillary testing up front would probably make much more sense in terms of trying to get that determination.
Speaker: Correct.
Speaker: Excellent.
Speaker: Well, I think that it's been a very interesting discussion.
Speaker: As I said before we started recording, I didn't want to dive into all the cases and controversies that have arisen over the last several years.
Speaker: People can look those up.
Speaker: I'm sure that a lot of people have experienced families that refuse to accept a diagnosis.
Speaker: and the legal battles in that respect have been well publicized in the press.
Speaker: But I do think that it's important to just review what we know about the clinical performance of this determination, what's the science available, and make sure that we provide our listeners with some good tools that we'll share in the podcast notes so they can educate themselves.
Speaker: This is something I think that
Speaker: happens in every ICU every year at least a couple of times and in very large centers can happen multiple times in a single year.
Speaker: One of the things that I also wanted to
Speaker: To do before we end is make sure you had shared in one of the chapters that you wrote, Fred, with me that there is a website from the Society of Neurocritical Care that really has a toolkit and a lot of education material that I think is very valuable.
Speaker: So I'll make sure that I put that in the show notes as well so our audience can go and check that out.
Speaker: You've been through this before.
Speaker: You know the drill, Fred, at the end.
Speaker: We kind of tap into your wisdom.
Speaker: So a couple of closing questions.
Speaker: The last time you were on the podcast, I asked you about books that were very influential, and you had mentioned Meditations by Marcos Aurelius, which happens to be also one of my most important books in terms of one that I try to read every year at least once.
Speaker: So I'm going to have to change the question today.
Speaker: If you were on a desert island and could only listen to one music album, which one would it be?
Speaker: So I hope in the island they have a USB connection so I can connect my iPhone to my iPod.
Speaker: It'll have to be vinyl.
Speaker: Vinyl, old school.
Speaker: Yeah, so there is one album that I love and it's Nevermind by Nirvana, 1991.
Speaker: And the reason why I love it so much is because that's the year when I got into medical school and the year where I had my first girlfriend.
Speaker: Believe it or not, I never had a girlfriend.
Speaker: I got my first girlfriend in medical school.
Speaker: And the best song is Come As You Are.
Speaker: We will include that in the show notes.
Speaker: I think that a lot of our audience might be too young to remember Rain and Nirvana.
Speaker: But definitely, I think, a phenomenal album.
Speaker: And I do have the vinyl.
Speaker: So I definitely will.
Speaker: Oh, you do?
Speaker: Oh, my gosh.
Speaker: You're lucky.
Speaker: It's an awesome album.
Speaker: I agree.
Speaker: So my second question relates to failure.
Speaker: We seem to always be fearful of failure, but I believe that failure should be embraced since it often is the best teacher that we have in life.
Speaker: Could you share with us a really good failure, one that really taught you something valuable?
Speaker: You know, talking about death and life situations, right, you know, one of my fears, right, in the intensive care unit, and we have talked about this before, right,
Speaker: It's the failure of being compassionate.
Speaker: And we have talked about this because of our experiences with mentors before.
Speaker: I fear failing in terms of being compassionate at the end of life.
Speaker: And it's something like the struggles that I have and it's
Speaker: If you're a physician in the ICU, it's not bad to go home and then cry a little bit about not being able to help somebody because you have failed miserably at being compassionate with that patient or family.
Speaker: So over the last five years, I've been changing the way that I approach these topics in the ICU with families.
Speaker: You know, sort of like discussing them at the same level with families is what I try to do.
Speaker: And failing to do that is what I'm afraid the most.
Speaker: So I think that this is definitely something that touches all of us who listen to critical matters and work in the ICU is recognizing that no matter how compassionate we believe we are, we probably have failed some patients.
Speaker: And recognizing that and learning from those experiences, I think, is instrumental in becoming better physicians and better providers for our patients.
Speaker: So the last question is, is there anything in particular specific that you would want every listener to our podcast to know?
Speaker: Could be a quarter specific fact of what we talked about.
Speaker: No, I think I will go back to their first podcast.
Speaker: I think that knowing death is an alternative as well and it could be a good outcome.
Speaker: Knowing that it's extremely important in the field.
Speaker: that we practice.
Speaker: So that doesn't have to be the worst outcome.
Speaker: It could also be a good outcome.
Speaker: And trying to understand the suffering from the patient and the family to better explain that when you think everything is just not going well, it's an extremely important thing that I would like everyone to know.
Speaker: Excellent.
Speaker: Fred, as usual, always a pleasure to talk with you.
Speaker: Thank you so much for being generous with your time and your knowledge.
Speaker: And we definitely, I mean, look forward to having you back on Critical Matters as one of our recurrent guests.
Speaker: Thank you very much.
Speaker: Thank you, Sergio.
Speaker: Thanks again for listening to Critical Matters.
Speaker: Make sure to subscribe to this podcast on iTunes or Google Play.
