BTK SCC Brain Death
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[00:00:00] Welcome back to Behind the Knife Surgical Critical Care Review Series. I'm Patrick Georgoff, trauma and acute care surgeon at Duke, and today I'm joined by my brother in light blue.

Hey. I'm Ian Kratsky, trauma and acute care surgeon at UNC. Go Heels.

Go Duke. Together, we are excited to bring another high-yield critical care case. You wanna dominate critical care? Let's get started. Today, we're covering brain death. Uh, the diagnosis of brain death adds immense complexity to an already devastating situation.

Our patients and their families deserve clarity when it's needed most. That's why a thorough understanding of brain death is super important for critical care providers.

Yeah. These are tough situations. It's just not something you wanna screw up.

Yeah, absolutely. Now, one important note before we get started, Ian.

Today, we are focusing on adult brain death only. Be aware, there are additional nuances when it comes to kids, so don't lump adults and kids together when assessing for brain death.

Oh, thank you, 'cause, [00:01:00] talking about brain dead kids is just truly soul-crushing.

Oh, yeah, I don't know if there could be anything worse.

All right, Ian, our case. We have a 27-year-old male who suffers a severe traumatic brain injury during a motorcycle accident. He has no other significant injuries. On admission to the ICU, he has a GCS of 3T. He does not follow commands, and he does not withdrawal to pain. Pupils are non-reactive, but he is breathing over the vent.

His ICP is measured via external ventricular drain, or EVD, and this ranges from 20 to 30 millimeters of mercury. Non-contrast CT scan shows diffuse cerebral edema, multifocal intraparenchymal hemorrhage, and a moderate-sized subarachnoid hemorrhage. Ian, can you start by giving us a little bit on the pathophysiology of brain death?

Because this is obviously important to understand as we work through the brain death diagnosis.

Yeah, sure. So injury to the brain results in brain swelling and increased intracranial pressure. And, you know, this leads to compromised blood flow and further hypoxic injury. Once the intracranial pressure [00:02:00] exceeds the mean arterial pressure, blood flow to the brain stops entirely, and the brain at that point may herniate through the foramen magnum.

Yeah, that's exactly right. Typically, the brain stem is the last part of the brain to suffer irreversible anoxic injury. And there are a multitude of homeostatic disturbances that accompany brain death as well, including hemodynamic instability, endocrinopathies, and hypothermia.

Yeah. Interestingly, the concept of brain death came into existence only in the 1950s after the introduction of positive pressure- Yeah

mechanical ventilation, you know. So prior to that, brain dead patients would rapidly succumb to hypoxic arrest. The first widespread clinical definition of brain death, known as the Harvard Brain Death Criteria, was published in 1968, and since then, many definitions, protocols, and guidelines have been created around the world.

Isn't that bonkers, Ian, to think that the first definition was 1968? Right. And we're really only talking about this as a result of mechanical ventilation.

Crazy.

Uh, it, it, that blew my mind. So the [00:03:00] next important date to remember is 1981. This is when the Uniform Determination of Death Act, AKA UDDA.

Was created by a presidential commission in cooperation with the American Medical Association and the American Bar Association, interestingly, right? So the legal folks are involved.

The UDDA defines death as the following. So this could be one of two things. First, an individual sustains irreversible cessation of circulatory and respiratory functions. That's easy, right, Ian? Mm-hmm. Their, their heart stops and they're dead, uh-

Sure ... you can

see. But, where the UDDA really started to add clarity to this whole idea of brain death is the second one.

So they define brain death as irreversible cessation of all functions of the entire brain, including the brain stem.

And it goes on to say that determination of brain death must be made in accordance with accepted medical standards. Yeah. Which is kind of an interesting concept, too. So what are those medical standards?

Who sets them? And that's part of this, this long tail in terms of the history of brain death, [00:04:00] where things can be confusing and errors have been made, which is, again, why this episode is so important for critical care fellows and staff to understand. Like, we cannot get this wrong. Right. It has to be tight.

Right. And, it's complicated further 'cause while all states, including DC, have adopted the UDDA, some have added additional regulations, so you need to know where you're practicing, what those regulations are.

So there are a few parts, uh, that deserve farther emphasis as well. So first, from a legal standpoint, as we mentioned, brain-dead patients are just as dead as patients whose heart has stopped beating. Which, again, can be a little disconcerting for the lay public or even providers when a patient's laying there with a beating heart and they're warm, but they're, they have cessation of all brain activity, including the brain stem.

And that brings us to our second point, the entire brain must be dead. This differentiates brain death from a persistent vegetative state or minimally conscious state, right? Important to differentiate.

So third, the determination of brain death must be made in accordance with accepted medical standards. Ian, we [00:05:00] mentioned this. What are those medical standards? Who determines them? What happens at the state level? This is why institutional protocols are so, critically important.

Right. Exactly. Luckily, there is a gold standard in the United States, and that is the 2023 Consensus Guideline on Brain Death, formally termed Brain Death, Death by Neurologic Criteria, or the BDDNC.

It was collaboratively developed by the American Academy of Neurology, American Academy of Pediatrics, Child Neurology Society, and good old Society of Critical Care Medicine. So this uniform guideline updates or replaces the previous adult guidelines from 2010.

All right, so this is, uh, a very good guideline.

This brought together some disparate recommendations at 2023, not that long ago. It's modern. It is a well-done guideline with a lot of specifics. And so, uh, you will inevitably at some point find yourself in a situation in the ICU where you're in the gray zone.

Yeah.

And you need to figure out what's going on.

This guideline is one you need to have on your phone. It needs to be searchable. [00:06:00] Uh, you need to use it and reference it, uh, uh, especially when it comes to things that start getting a little bit muddy. You may just find that these guidelines have the exact answer to the very question that you're wondering, and we're gonna talk about some of those specifics when we go through the diagnosis of brain death today.

All right, we're gonna teleport back to the unit where we are caring for this guy who was in a bad wreck. Remember, bad brain injury. It's now post-injury day one, and we have maxed out our ICP management strategies. His head is raised, cervical collar has been removed, PaCO2 is optimized, deeply sedated with fentanyl and propofol, and he's been paralyzed with cisatracurium.

We mentioned he has an EVD, so we're also draining CSF, and the patient is extra salty from hypertonic saline administration. He is on low-dose norepinephrine to keep cerebral perfusion pressure up, and repeat head CT scan is unchanged with no midline shift or significant change in the bleeding. The neurosurgery team has already decided against decompression.

You examine the patient, and he has no purposeful movement and no brain stem [00:07:00] reflexes. So after you finish your exam, the patient's mother asks, "When is my son gonna wake up?"

Oh, damn.

Yeah. Uh, heartbreaking. But-

Yeah ...

Ian, you're there. She asks you this.

It's a legitimate question. Right. She has to know what the brain death criteria are. What are you gonna tell her?

Well- I would tell her the truth. I would clearly state that her son has a very severe injury and it's resulting in brain swelling. I would tell her I'm worried that her- his brain might be dead.

So I'd also inform her that our team is gonna carefully examine her son today to better understand if her brain- if his brain is still functioning.

Yeah. Clear, objective, don't muddy the water, state it plainly. That's what our patients and their families deserve. So you're setting this patient, uh, the patient's family up for a brain death exam- Right

to be performed. So what do you need to know, Ian, when it comes to the exam? Uh, all fellows, staff at some point are gonna be called to the patient's bedside to be involved in this absolutely critical [00:08:00] examination and decision-making process

Yeah. First it's important to understand that the determination of brain death, it's a clinical diagnosis. Correct. Before we can make that diagnosis, there's very specific criteria that have to be met.

So let's get through all those prerequisites for the clinical exam. First there has to be an identified mechanism that's known to lead to brain death, and there cannot be brain death mimics like Guillain-Barre or locked-in syndrome.

Dude, could you imagine that? Terrible. I mean, locked-in would be, you know, atrocious, but- you can see how that could be confusing. Yeah. On the other hand, it's egregious that those things have ever been misdiagnosed, again, if you follow these criteria we're talking about to the T.

Right.

So I'll take this next one, okay? Oh, yeah. So we determined that you have to have a known mechanism, right? This guy that was in a motorcycle crash, that checks the box, right? We know it's traumatic. And in our world, in surgical critical care, a whole lot of this is gonna be- Yeah ... traumatic in nature.

So the second thing is you have to have neuroimaging consistent with [00:09:00] mechanism and severity of brain injury. You can't have a clean CT or MRI, right? And in our case, we've checked that box.

Right. Then you have to observe the patient for at least 24 hours or, a sufficient amount of time after brain injury to ensure that there's no potential for recovery of brain function as determined by you, the evaluator, based on the pathophysiology of the brain injury.

So y- you can't decide this, they come into trauma, you get the devastating CT scan, you can't say they're brain dead. Yeah. You know, things change. You gotta watch them for at least 24 hours.

And this is an important component of the new guidelines, the 2023 guidelines. They say 24 hours.

Yeah.

Okay? Uh, it's not three hours and you're making a diagnosis, 24 hours plus.

And that meant, I- and you had mentioned this, quote, "sufficient amount of time" to ensure other things aren't going on. That's very vague. Yeah. Uh, what that means is if you have any questions about anything at all, more time is typically the answer. This is not something to be rushed.

Exactly.

The next uh, feature or specific criteria that needs to be met is the core body temperature should be above 36 degrees.

We can warm patients to get there.

[00:10:00] Yep. Um, also obviously important in trauma patients. Mm-hmm. Next would be their systolic blood pressure has to be greater than 100 or MAP over, uh, 75. And interestingly, this can be with or without vasopressors.

Yeah, I've seen people get confused with this. They say, "Okay, well, their systolic blood pressure is 90."

Right. "And they're on nor- but they have to be on norepinephrine to get them up, therefore they're excluded." That's not true. Right. You just need to be perfusing the brain with or without pressors. Uh, next, you have excluded pharmacological paralysis through the use of train of four st- uh, stimulation or demonstration of deep tendon reflexes.

So what does this mean? Well, a- as we mentioned in, in our other episodes, we talk about ICP management. A lot of that requires deep sedation and/or paralysis as you move along the stepwise management of elevated ICP. So you don't wanna confuse someone's exam with paralysis from um, medications you administered.

So this is also newer, the, uh, exact recommendation of train of four, which, you put the little [00:11:00] electrodes on, give a little twitch- Mm-hmm ... see what happens, or deep tendon reflexes.

Yeah, and that's common, right? Like our patient w- was- Yeah ... was on cis. So you gotta wait for that to wash out. Speaking of washing out medications, the next is that drug levels for meds that can suppress the nervous system, um, have had at least five half-lifes to clear. And so that's gonna depend on the medication, right?

Longer if that patient has renal or hepatic dysfunction if the patient is obese and maybe can be trapping some of those meds, or if they were hypothermic and not clearing them as fast. So, interestingly, some specific levels are phenobarb has to be less than five mics per mil, or an alcohol level has to be less than 80 mics per, uh, DL.

So, um, a lot of our patients, maybe if they were drunk driving, you gotta make sure their alcohol's washed out of their system.

Yeah. Pentobarbital, just like cis, right? We're managing, traumatic brain injury,- elevated ICPs. You move to cis, you move to pentobarbital, comas, et cetera. These things will um, can confuse the brain death exam, so it's extremely important.

And this is also what I was talking about when you [00:12:00] look at this guideline. If you need specifics, well, hey-

There's your number ...

yeah, here you go. Pentobarbital less than five. Having that extra clarity is so, critical, uh, when it comes to, uh, initiating your exam.

Next, uh, in a similar vein, toxicology screen should be negative.

Yeah, straightforward. And then this one I think is- is something that you really gotta pay attention to. Um, the- the patient cannot have any severe metabolic, acid-base, or endocrine derangements, right? So for example, they cannot have uremia, hyperammonemia, hypernatremia, or hypoglycemia.

And so in the setting of severe TBI, many of these patients may develop DI or diabetes insipidus or they're very frequently treated with hypertonic saline-

Mm-hmm ...

which leads to severe iatrogenic, but purposeful hypernatremia. The, you know, the 2023 guidelines emphasize there's no absolute cutoff for the number for sodium or extreme hypernatremia but it needs to be corrected or at least [00:13:00] stabilized before the exam to ensure that this isn't the primary cause of coma.

So if that patient is salty up to above 160, you gotta make sure that it's not continuing to go up or y- or y- that's not the cause of their mental status.

Yeah. A little gray zone there, right? So that's one to be careful with. And finally are these recommendations as Ian, you had mentioned when that mother asks, you said- Yeah

you set them up to do the brain exam. We should tell the patient's family we're doing the brain exam. Right. When you're dealing with something as sensitive as brain death- Any family or folks involved in that patient's care should be, uh, made aware of what's going on.

And, uh, most hospitals have very clear guidelines for these features. Now, really what that means now is that 2023 guideline essentially has been, for the most part copy and pasted into an institution's guidelines. And really where there's more variability are things like - this is stated within the guidelines as well, but who exactly at the institution can examine?

Does it have to be a neurointensivist or a neurosurgeon or a critical care, uh, doc from the trauma [00:14:00] team? Can it be two trauma doctors, or does it have to be neuro and trauma? Right. There's, there's different recommendations at different institutions and/or maybe how many exams need to be performed, how far apart they might need to be.

That's where you start getting into a little bit more of the variability, 'cause you should have no variability outside of those specific criteria that we talked about. So again, highly recommend that you print out those guidelines, check the boxes one by one. So Ian, our patient meets all these criteria.

And, we've , literally printed something out at the bedside and checked the boxes to make sure we're not missing anything.

Mm-hmm.

And they've been off sedation and paralysis. Their sodium levels are normalized. What do we do next?

Well, it's time we do the exam, right? We check for complete absence of response to visual, auditory, and tactile stimulation with the absence of pupillary, oculocephalic, also known as doll's eyes oculovestibular, AKA cold calorics corneal, gag, and cough reflexes.

Yeah. So you listed a whole bunch of different things there, right? We're looking at the eyeballs. Mm-hmm. We're [00:15:00] putting cold water in the ears and doing all these different things. If you haven't done this, very frequently it may get a little overwhelming or confusing. This is also why you wanna checkbox.

And I think, a quality guideline should have those exact things listed and then say exactly how to do it. Right. Anyone can do it. It's not hard, and these tests are not hard to interpret, but they need to be done appropriately, so having that clarity in the guidelines is super-duper important.

And it's really important to note that spinal reflexes don't count as movement. So remember, spinal reflexes can occur in over half of brain-dead patients.

Right, and they can be complex movements, you know, like head turning and triple flexion, although maybe not that common.

But if present, it can really complicate the situation and be fairly distressing to family members, as it appears that their loved one is moving or responding to something.

Oh my gosh, absolutely, and it's understandable why. Another thing that can get confusing, you know, we're intri- we're gonna talk about the apnea test in a minute here, but spontaneous abdominal contractions can actually- Right

trigger the ventilator. That [00:16:00] gets really confusing. But it requires a keen eye to maybe pick that up and try to tease that out from actual respiratory function at the brainstem level.

And another important caveat here, if, if your patient potentially has a cervical spine injury or there is issue to their trauma to their skull base, you can actually skip the doll's eye test. Um, as long as everything else is complete then you're good to go.

Yeah, this is really common, right?

We have that checkbox and you think, "Oh, crap, I got through it. The person has a cervical collar on. I can't go twisting their neck back and forth- Mm-hmm ... therefore, I can't determine brain death." the 2023 guidelines clarify that you can in fact, uh, do so. The presence of a cervical collar does not preclude a brain death exam.

You need to complete the entire rest of the exam and document why that single piece hasn't been completed, but it does not preclude the rest of the exam and the findings. So back to our patient. He meets the prerequisites and his exam is consistent with brain death. What next, Ian? All

right. Well, now we need to do a single apnea test.

So, and this is, [00:17:00] you know, kind of what everybody thinks about brain death testing is the apnea test. Well, it took a lot to get here, and we're finally here. The goal of the apnea testing is to trigger respiratory centers in the medulla by allowing serum carbon dioxide levels to rise. In general, it's recommended that an apnea test be performed after the clinical testing is found to be consistent with brain death and after temporarily placing the patient on spontaneous ventilator mode and observing the absence of respiratory activity or breathing.

Y- you need to note that apnea testing is contraindicated with patients that have high C-spine or phrenic nerve injuries. And most institutions will have their own protocol for apnea testing. So again, make sure you're following those when you're doing this.

That's right, Ian. In general, the patient is pre-oxygenated with 100% FiO2, and the ventilator is adjusted to obtain normal carbia. Now, some patients have baseline elevated CO2, especially patients with COPD, for example. For them, you wanna ensure that you get the CO2 levels back to baseline, even if that's elevated, and you can look at their [00:18:00] history of gases to determine that.

Now the ventilator is then turned off, okay? But oxygen is still delivered via, for instance, blow-by mechanisms like a T-piece. And apnea is confirmed in the absence of respiratory effort when pH has dropped sufficiently low below 7.3, and CO2 has risen to above 60, or in the case of someone with COPD or baseline elevation, their CO2 has risen to 20 above the pre-apnea baseline.

And this is usually determined by repeating ABG, oftentimes seven to nine minutes or so. The, the exact number may vary depending on your institution after that apnea test is, uh, started. And not all patients tolerate an apnea test, right? For example, patients can become hypotensive, hypoxic, especially if they have concomitant lung injury or develop [00:19:00] arrhythmias before you can get the CO2 high enough.

All right, Ian, so we need to talk about the patients who can't complete an apnea study or don't meet those specific prerequisites that we talked about to perform a clinical exam. Yeah. This happens not infrequently.

So for example, what if we don't meet those prerequisites to be able to perform clinical testing? We're in the trauma world here. Let's say this guy also had bad facial injuries, and one or both of his eyes are completely swollen shut, precluding exam.

Yeah.

Well- Or maybe with the apnea test too, Ian, right?

Maybe you had to bail on that. It's not unusual that patients become unstable during the apnea test. We talked about waiting around for seven minutes or so. Especially if you have issues with hypoxia, maybe they have a lung injury, a bad contusions or ARDS, and you need enough time to get the CO2 level up so high enough that it stimulates the chemoreceptor reflexes at the brain stem level.

That's where you're looking at. Does the brain stem gonna respond? [00:20:00] But if you don't get that seven minutes because the patient's so hypoxic that their sats are dropping- Right ... and they start having an arrhythmia, and you're pushing a pressor and getting them back on real quick, that means you can't complete the exam.

And this is fairly common- This happens ... especially in polytrauma. So Ian, what do we do when we can't- Yeah ... complete these things?

Well, this is where ancillary testing comes in. This should be performed whenever those specific components of clinical testing can't reliably be performed or finished.

So Ian, what are your options when it comes to ancillary testing?

Generally, there's two types of ancillary tests.

There's those that evaluate the blood flow to the brain and those that assess the EEG function of the brain. So like somatosensory, audio, or visual evoked potentials. Those consensus guidelines that we talked about from 2023 recommend studies that evaluate blood flow and no longer accept those that assess the electrophysiologic function.

So EEG used to be a major part of this, but it is now, uh, no longer [00:21:00] recommended. And in fact, the 2023 update made EEG and evoked potentials along with CT and MR angiography unacceptable as ancillary tests. So what does that mean? Well, it means the most commonly used test is a nuclear medicine flow study.

And then to a lesser extent, there's also transcranial Doppler ultrasound.

Yeah. And while CTA has been used to diagnose cerebral, uh, circulatory arrest, the guidelines recommend that these modalities not be used until further research is performed, probably in the future. Uh- Yeah ... CTA will be used more.

But right now, like you mentioned, nuclear medicine flow study and to a lesser extent transcranial Doppler ultrasound.

So the diagnosis of brain death, it's made when there is complete absence of blood flow to the brain. It's important to note that the loss of flow defines loss of function, but the presence of flow does not indicate the presence of function, meaning no flow at all to your [00:22:00] brain means brain death. But some flow to the brain does not necessarily mean that the brain's functioning, so you really should consider this before you're ordering a flow study for any patient, especially those that have a complete clinical exam consistent with brain death, as that would really muddy the water.

Right. And that's why we recommended this as, again, a clinical diagnosis. If you're able to meet the prerequisites, perform your clinical exam, and identify absence of brain and brain stem function, and an apnea study shows no respiratory effort, you've diagnosed brain death. Throwing around these studies like a nuclear medicine scan kinda willy-nilly can lead to severe muddying of the water.

Yeah.

But what happens, you know, when you go examine, that, that mother's there. You say, "Okay." You do your exam, check all the boxes, and it's consistent with brain death. And for whatever reason, someone wants to get a flow study, and that flow study shows a smidge of flow to the brain.

Mm-hmm.

What does that mean then, right?

That gets awfully confusing. And so, this is a, really a really important point. [00:23:00]

Yeah. Yeah. You should only be doing the ancillary tests when those specific components of the clinical testing cannot be reliably performed or evaluated.

Okay, Ian this is another kind of logistical thing that comes up all the time. How do you report the time of death in a brain death patient whose heart's still beating?

Yeah. Great question. Well, time of death is the time that confirmatory ABG is drawn during the apnea study, or it's the time when the attending radiologist has documented those ancillary findings as being consistent with brain death on their on their exam.

All right. That's a good, a good point to know. So let's wrap this up with a particularly shitty twist to our case. You, the attending physician, carefully and completely perform your evaluation, Ian, and the findings confirm brain death. You share this information with the family in a clear and compassionate way.

After giving the family some time, you come [00:24:00] back and do your best to explain that the brain death is in fact real death, that the only thing keeping their, uh, loved one alive and their heart beating is the ventilator itself And that they will be, uh, extubated after family visits have had a chance to occur.

Unfortunately, the patient's family refuses to accept this, and despite your best efforts at communication and clarity, they accuse you of murdering this patient by disconnecting them from the ventilator.

It's awful. They see that there's still vitals there on the monitor, and you're about to take that breathing tube out.

It's terrible.

Right. So what do you do in this circumstance, Ian?

Well, just like everything else we talked about in this podcast, I'm gonna follow the guidelines. So those state that mechanical or pharmacologic support that's maintaining respiratory or cardiac function is generally discontinued unless organ donation is being considered.

However, it's reasonable for the organ support to be continued for a [00:25:00] period, providing the family with a reasonable but limited amount of time with the deceased patient.

Yeah. So what is a reasonable amount of time then?

Yeah, exactly. The guidelines do not define that part. However, another really, really fantastic document is called the World Brain Death Project.

It was published in 2020, and it suggests a 48-hour time limit. Uh, that's a limit that I've seen multiple institutional protocols as well.

Yeah. That document, the World Brain Death Project from 2020, is also, uh, exceptional, and there are some bits of information in there that can help with guidance, like we pulled out for this specific case, that may not be covered in the 2023 guidelines.

Mm-hmm.

All right. So, you're at 48 hours, Ian.

Yeah.

Family is still holding on hope. Um, again, they see the heart beating, the patient warm. They're watching the monitor. What do you... Do you walk in there and say, "Hey, 48 hours is up. Tube's out. We're pulling it out"?

No. Yeah. It it can be [00:26:00] hard. Honestly, it's Never come to that, luckily, in my experience, but this is where those in-depth discussions the face time with the patient's family, having real compassion all come into play.

You know, this is complicated, terrible stuff, and it can be really challenging to understand, especially in the setting of a sudden tragedy where family members are fiercely holding on to any last bit of hope that they can. But when you demonstrate true compassion and you communicate clearly and your team delivers a consistent message, the majority of the time family members will come around.

Yeah, I agree. And I really like your point regarding delivering a consistent message, right? This is all about communication, and it's also about consistent communication. There's multiple providers at different levels caring for that patient, and one little bit of miscommunication can really throw a wrench, uh, in these affairs.

All right. [00:27:00] Ian, that was intense. It was thorough, though. So let's end with some quick hits.

Brain death, what is it?

Brain death is legally and medically equivalent to cardiopulmonary death. So it requires irreversible loss of all brain function, including the brain stem, and it is not to be confused with coma or vegetative states.

Okay. Prerequisites matter. What are they?

So before any exam, ensure that all those clinical prerequisites are met.

There must be a known catastrophic brain injury, an appropriate amount of observation time after that injury. The patient must be normothermic, hemodynamically stable, even if on pressors. There must be clearance of any sedatives, paralytics, or any metabolic confounders.

Yeah. What, uh, form the core of this brain death testing that we do?

Yeah. The adult guideline requires one complete clinical exam and one apnea test. Brain stem reflexes and motor responses must be [00:28:00] absent, but spinal reflexes may persist, and those do not preclude the diagnosis.

Okay. When do we use ancillary testing?

Only for incomplete exams. So you use flow-based studies like nuclear medicine scans when a component of the clinical or apnea exam cannot be completed, but be cautious.

The presence of blood flow does not equal brain function.

Okay. What about documentation? How do you go about this?

Yeah. It's super important. Every element of the exam, the apnea test, or the ancillary study must be thoroughly documented.

And then the time of death is recorded at the time that ABG is drawn at the end of the apnea test or at the time of the attending radiologist's interpretation of the ancillary study.

And last, how about some key points for communication with, uh, patient family members?

Yeah. Compassionate, clear communication, team consistency are key when guiding families through a brain death diagnosis.

Most families will eventually accept the reality of brain death when treated with honesty and empathy. [00:29:00]

Agree with that. All right. That does it for this episode of the BTK Surgical Critical Care Review Series. Until next time, Ian?

Dominate the day.