Become a Creator today!Start creating today - Share your story with the world!
Start for free
00:00:00
00:00:01
Brain Death / Death by Neurologic Criteria
18 Plays2 years ago
In this episode, we discuss the topic of Brain Death / Death by Neurologic Criteria. We discuss updates from the recently published American Academy of Neurology, American Academy of Pediatrics, Child Neurology Society, and Society of Critical Care Medicine clinical guidelines. Our Guest is Dr. David Greer. Dr. Greer is a neurologist with additional vascular neurology and neurocritical care training. He is the Chair of the Boston University School of Medicine Department of Neurology. Dr. Greer is a renowned clinician, educator, and researcher. He has an extensive list of publications and awards. He is the first author of the “Pediatric and Adult Brain Death/Death by Neurologic Criteria Consensus Guideline” we will discuss today.
Additional Resources:
Pediatric and Adult Brain Death / Death by Neurologic Criteria Consensus Guideline. David Greer, et al. Neurology 2023: https://n.neurology.org/content/early/2023/09/13/WNL.0000000000207740
Determination of Brain Death / Death by Neurologic Criteria. The World Brain Death Project. D. Greer et al. JAMA 2020 https://pubmed.ncbi.nlm.nih.gov/32761206/
Determination of Brain Death / Death by Neurologic Criteria. The World Brain Death Project. VIDEO: https://edhub.ama-assn.org/jn-learning/video-player/18529668
Controversies in Brain Death Declaration: Legal and Ethical Implications in the ICU. S Biel, et al: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7223748/
Books mentioned in this episode:
The Boys in the Boat. By Daniel J. Brown: https://www.amazon.com/Boys-Boat
Team of Rivals: The Political Genius of Abraham Lincoln. By Doris Kearns Goodwin: https://t.ly/7F1My
Nine Stories. By JD Salinger: https://t.ly/qM5w_
Recommended
Transcript
Introduction to Critical Matters Podcast
00:00:06
Speaker
Welcome to Critical Matters, a sound podcast covering a broad range of topics related to the practice of intensive care medicine.
00:00:14
Speaker
Sound provides comprehensive critical care programs to hospitals across the country.
00:00:19
Speaker
To learn more about our programs and career opportunities, visit www.soundphysicians.com.
00:00:26
Speaker
And now your host, Dr. Sergio Zanotti.
New Clinical Guidelines for Brain Death
00:00:32
Speaker
In a previous episode of Critical Matters, we discussed the concept of brain death, death by neurologic criteria, through the lens of the World Brain Death Project.
00:00:40
Speaker
In today's episode, we will return to this topic and focus our discussion on the recently published American Academy of Neurology, American Academy of Pediatrics, Child Neurology Society, and Society of Critical Care Medicine clinical guidelines for the evaluation of brain death and death by neurologic criteria.
00:00:57
Speaker
Our guest is Dr. David Greer.
00:00:59
Speaker
Dr. Greer is a neurologist with additional vascular neurology and neurocritical care training.
00:01:04
Speaker
He is the chair of the Department of Neurology at the Boston University School of Medicine.
00:01:08
Speaker
Dr. Greer is a renowned clinician, educator, and researcher.
00:01:11
Speaker
His research interests include predicting recovery from coma after cardiac arrest, brain death, and multiple stroke-related topics.
00:01:19
Speaker
Dr. Greer is a leader in the Neurocritical Care Society, Society of Critical Care Medicine, and the American Stroke Association.
00:01:25
Speaker
He has an extensive list of publications and awards.
00:01:28
Speaker
He is the first author of the Pediatric and Adult Brain Death, Death by Neurologic Criteria Consensus Guideline we will discuss today.
00:01:35
Speaker
Dave, welcome back to Critical Matters.
00:01:38
Speaker
Thank you, Sergio.
00:01:39
Speaker
It's great to be here.
Terminology and Age Group Guidelines
00:01:41
Speaker
So as you were discussing before we started recording, there's a new combined adult and pediatric clinical guideline that just got published by multiple societies.
00:01:50
Speaker
You're the first author of that.
00:01:52
Speaker
A very important topic, the topic of brain death and death neurologic criteria.
00:01:58
Speaker
Today we're going to focus on the adult patient just because that is our main focus on the podcast.
00:02:07
Speaker
But I guess where appropriate if you want to just highlight some of the importances or differences, since this is a combined document, that would be great.
00:02:17
Speaker
But I wanted to start as a way of introduction with just some terminology.
00:02:22
Speaker
And if you could really just give us your thoughts and how the guideline group thought of brain death, death analogy criteria, the word irreversible and the word permanence.
00:02:36
Speaker
Sure.
00:02:36
Speaker
So it's a great question.
00:02:37
Speaker
I'll take the first part first.
00:02:39
Speaker
So brain death, quote unquote, is what has been used colloquially for decades now.
00:02:45
Speaker
And I think it's the term that most people are familiar with and certainly the lay public is familiar with.
00:02:50
Speaker
But death by neurologic criteria is a more accurate term.
00:02:54
Speaker
term to be used.
00:02:55
Speaker
It means that we are determining that someone is dead based on criteria that are brain-based and not cardiopulmonary-based as the prior definitions of death were.
00:03:07
Speaker
So rather than trying to choose one versus the other and upset one group versus another, we decided to include both
00:03:17
Speaker
and call it BD slash DNC, grain death slash determination death by neurological criteria.
00:03:26
Speaker
That kind of captures both feelings.
00:03:28
Speaker
In terms of the use of the word permanent instead of irreversible, the panel chose to use the term permanent to mean that function was lost and, number one, would not resume spontaneously, and, number two, medical interventions would not be used to attempt to restore function so that you could have a patient who has, for example, a very severe cerebral edema
00:03:54
Speaker
due to a massive ischemic stroke, you wouldn't do a hemicraniectomy on that patient if you felt that the prognosis was futile.
00:04:02
Speaker
And so that takes away the possibility that a surgical or medical intervention would reverse the condition.
00:04:10
Speaker
So that's why we use the term permanent to establish that difference.
00:04:17
Speaker
Perfect.
00:04:18
Speaker
And in terms of these new guidelines, one of the things I immediately noticed is that it's a combined adult and pediatric.
00:04:25
Speaker
But could you just comment on general terms, some of your impressions of the guidelines and why they're so important for intensivists to be aware of?
00:04:35
Speaker
Sure.
00:04:35
Speaker
So just to remind the listeners that we had two separate sets of guidelines for adult and pediatrics previously.
00:04:41
Speaker
The AAN, or American Academy of Neurology, guidelines for adults came out in 2010, and the AAP, or American Association of Pediatrics, along with SCCM,
00:04:54
Speaker
and the Child Neurology Society had their guidelines in 2011 and for the most part they were quite similar but there were some notable differences for mostly subtle things like having two minimum temperatures.
00:05:07
Speaker
Pediatrics had 35 degrees and adults had 36.
00:05:10
Speaker
The exam techniques were a little bit different, the waiting periods were different, the use of ancillary testing was different and
00:05:19
Speaker
There were a number of lawsuits that came out, particularly in the pediatric age groups for teenagers where there was concern regarding the diagnosis or the permanency of the state based on those legal cases, not based on the guidelines.
00:05:39
Speaker
But we decided that it would be prudent to combine the guidelines where we could for adult and pediatrics because most things are really quite similar.
00:05:50
Speaker
including, for example, the neurological exam and confounders.
00:05:54
Speaker
So we did that to provide unified guidance, but also to give carve-outs for pediatrics because
00:06:04
Speaker
their cranial physiology is different below the age of two, that they have open sutures and fontanelles that may allow for more intracranial expansion.
00:06:15
Speaker
They have different blood pressures based on their ages and so
Addressing Special Cases in Guidelines
00:06:20
Speaker
forth.
00:06:20
Speaker
And so that's why we combined them where we could, and then we called out where they were different and necessarily different.
00:06:27
Speaker
We continue to try to move towards a very stringent and
00:06:34
Speaker
conservative approach, not that we weren't stringent and meticulous before, but with every iteration, it becomes, I would say, really a bigger point of emphasis and erring on the side of not determining that somebody's brain dead without absolute certainty.
00:06:50
Speaker
That's a theme that you can see throughout this time.
00:06:53
Speaker
document that we really want to make sure that people are absolutely certain.
00:06:57
Speaker
And then the last thing I'll say is there were areas where there was a need for new guidance that hadn't been touched in prior guidelines such as what about patients who do undergo an intracranial procedure?
00:07:09
Speaker
How do you proceed there?
00:07:10
Speaker
What do you do about patients who have a primary infratentorial injury such as a brainstem or cerebellar stroke?
00:07:17
Speaker
How can you be sure that they have concomitant supratentorial injury?
00:07:22
Speaker
What do you do about patients who are on ECMO or have been hypothermic, either iatrogenically or environmentally?
00:07:29
Speaker
What about pregnant persons?
00:07:31
Speaker
How about the need for consent?
00:07:33
Speaker
And then we also specified regarding the neuroendocrine function, how that can be variably preserved and still be a brain dead patient.
00:07:43
Speaker
So those are some of the things that we, in general, added that we thought would be useful for practitioners.
00:07:49
Speaker
Absolutely.
00:07:50
Speaker
And one of the things that struck me reading the guidelines is exactly what you mentioned, almost like a philosophical approach that reminded me of our justice premise that everybody is innocent to proven otherwise.
00:08:04
Speaker
And it feels like our approach should be people are not brain death unless we can absolutely prove otherwise.
00:08:11
Speaker
Correct?
00:08:11
Speaker
Absolutely.
00:08:12
Speaker
That's 100% correct.
00:08:13
Speaker
So we are looking to disprove that they are alive.
00:08:18
Speaker
So we're going into this looking for signs of life to disprove that they have brain death.
00:08:24
Speaker
And so it's only after you've done everything meticulously and you've ruled out any signs of life that you can say definitively if someone is brain dead.
00:08:33
Speaker
Perfect.
00:08:34
Speaker
So let's start into going in a little more detail into some of the areas of the guidelines.
00:08:39
Speaker
The guidelines are organized in different categories.
00:08:42
Speaker
And then there's really an enormous number of recommendations with rationales and supporting evidence.
00:08:48
Speaker
But in terms of general principles for evaluation of BD slash DNC, like we mentioned, when should we consider this evaluation?
00:08:57
Speaker
When should we start thinking about maybe I should evaluate this patient for BD slash DNC?
00:09:03
Speaker
Yeah, I would say any patient with a neurological catastrophe who has minimal to no brain function initially, they have to be a little careful in patients with cardiac arrest, and I'll get to that in a minute.
00:09:15
Speaker
But the other areas are making sure that there's no confounding.
00:09:19
Speaker
And then from the new in the guidelines,
00:09:22
Speaker
making sure that you have neuroimaging consistent with what I call cerebral circulatory arrest, or you can colloquially call it a no-brainer scan, that it looks so disastrous that you can make the argument that there's no way that there could be blood getting into that cranium based on the degree of swelling that is present.
00:09:42
Speaker
And so we really put an emphasis on having neuroimaging that's consistent with that cerebral circulatory arrest.
00:09:50
Speaker
The times that you can be
00:09:52
Speaker
Potentially Fooled is early on after a cardiac arrest where a patient can look brain dead and this has been known for decades but they can regain neurological function so you always have to wait at least 24 hours in a cardiac arrest patient and if you cooled them you have to wait for longer you have to wait 24 hours after they've been completely rewarmed and I always try to get a second CT scan or even MRI at that time point to make sure that I've got neuroimaging that's entirely consistent with brain death.
00:10:23
Speaker
Dave, is there in the new guidelines any indication of who in terms of expertise should be doing these BD DNC evaluations?
00:10:33
Speaker
Yeah, so that was an area where we really had a lot of discussion.
00:10:36
Speaker
And we came down by saying that as attending clinicians performing exams must be appropriately credentialed members of the hospital's medical staff and adequately trained and competent in the evaluation of brain-dead patients in adults or children as applicable.
00:10:52
Speaker
And this could include intensivists, neurologists, or neurosurgeons, but others as well.
00:10:58
Speaker
And in accordance with local laws and institutional standards, there were some
00:11:02
Speaker
places where advanced practice practitioners perform this and perform them independently.
00:11:09
Speaker
And we said that that's in accordance with local laws and institutional standards.
00:11:13
Speaker
They also have to be appropriately trained and credentialed and competent in the evaluation in children.
00:11:21
Speaker
However, trainees or acute care critical care APPs in settings where they're not permitted to do independent evaluations must be directly supervised by an attending physician who themselves meets the criteria for adequate training and credentialing.
00:11:40
Speaker
And in terms of what that specific education includes, it can be a completion of a supervised evaluation in a clinical environment or supplementary education in online courses, such as what's put on by the Neurocritical Care Society, which I strongly recommend.
00:11:59
Speaker
But the best is really training with a mannequin, and there are
00:12:04
Speaker
new courses that will be coming out that can be very helpful for working through challenging scenarios, especially working on exam technique with a mannequin, which I strongly recommend.
00:12:16
Speaker
Perfect.
00:12:17
Speaker
And in terms of you mentioned a little bit about some of the prerequisites before we start evaluating patients and determine where they have BD slash DNC, you talked about identifying an etiology for a devastating, catastrophic neurological injury.
00:12:33
Speaker
We talked about having neuroimaging that supports that.
00:12:37
Speaker
There's also in the literature mention of reversible mimics or potential diseases that could fool us.
00:12:42
Speaker
You did talk about the early phases of
00:12:45
Speaker
cardiac arrest.
00:12:47
Speaker
Could you mention other reversible mimics that we should be aware of in our differential?
00:12:52
Speaker
Yeah, so there's new guidance now that's provided in the guidelines regarding the different drugs and their potential metabolism based on age and obesity, metabolic dysfunction in the patient, etc.
00:13:05
Speaker
But there's also guidance regarding the different metabolic derangements that patients can have.
00:13:11
Speaker
And this was
00:13:12
Speaker
clamored for by people for years that they wanted some guidance regarding practical thresholds for things like sodium, BUN, ammonia, etc.
00:13:23
Speaker
So we provided that.
00:13:23
Speaker
And I just want to give the caveat that this is consensus-based and people need to use their judgment in individual cases.
00:13:29
Speaker
But there is new guidance regarding those things which hopefully will satisfy people in that regard.
00:13:34
Speaker
And any comments also on hypothermia, hypotension?
00:13:41
Speaker
Right, yeah, so hypothermia is a big one to watch out for, either atrogenic or environmental.
00:13:48
Speaker
And so now we say that the person has to be at least 36 degrees for at least 24 hours.
00:13:55
Speaker
So if they were less than 35.5, you have to re-warn them and you have to wait for 24 hours.
00:14:01
Speaker
And why, you may ask, and we'll say, well, we had to draw the line somewhere.
00:14:05
Speaker
And again, it's a conservative approach, making sure that there's no
00:14:08
Speaker
false positive determination because when you look at the case reports that have come up with false positive determinations hypothermia is a big one.
00:14:16
Speaker
And then hypotension also we not only have a systolic blood pressure minimum requirement of 100 but also a mean arterial blood pressure of at least 75 because both are important obviously and now that guidance is there and that's both for patients on or off ECMO
00:14:35
Speaker
Obviously, if they're on VA, ECMO, and a non-pulsatile heart, then at least the MAP of 75 is required.
00:14:41
Speaker
In children, it's greater than the fifth percentile for age, so that's relatively straightforward.
00:14:47
Speaker
One caveat to think about is patients who are chronically hypertensive, that if you think they might be living at a higher blood pressure, then that should be the blood pressure that you aim for.
00:14:56
Speaker
But we didn't put specific parameters to that, but it's a consideration, again, if you're going to have a conservative approach, which we recommend, then consider if the patient might be chronically hypertensive and require a higher blood pressure during testing.
00:15:11
Speaker
Perfect.
Neurological Exam and Apnea Test Procedures
00:15:12
Speaker
So once we've determined that any potential reversible mimics has been addressed with, we've taken care of making sure the patient has a catastrophic injury that would support the diagnosis of BD slash DNC, we start with a neurologic examination.
00:15:32
Speaker
What is required in terms of this evaluation?
00:15:35
Speaker
What are the components of the whole evaluation?
00:15:38
Speaker
And then the other thing I wanted to ask you about is for the exam itself, how many exams and what's the timing for all this?
00:15:47
Speaker
Yes, so the clinical evaluation remains the same, and that is that you have to have a patient who's in coma, has no brain stem reflexes, and has apnea in the face of a hypercarbic and acidotic challenge.
00:16:02
Speaker
So coma means an absence of all unresponsiveness to auditory, visual, and tactile stimulation.
00:16:09
Speaker
Loss of brainstem reflexes includes all of the reflexes that we've previously tested, including pupils, corneals, oculocephalic, oculovestibular, gag and cough reflexes.
00:16:21
Speaker
And then the apnea test, I'm sure we can get into as well, but again, that's allowing the patient's PCO2 to rise and their pH to drop below certain thresholds.
00:16:34
Speaker
And then showing that their medulla does not kick in and trigger for the patient to take a breath.
00:16:40
Speaker
In terms of the number of examinations, it remains two examinations and two apnea tests in children
00:16:47
Speaker
And in adults, we say one examination is the minimum criteria and definitely only one apnea test.
00:16:55
Speaker
However, we do say that performance of a second examination in adults may decrease the risk of a false positive determination due to diagnostic errors.
00:17:05
Speaker
So we fall short of saying that two examinations are required in adults, but you can read that as it's strongly encouraged.
00:17:12
Speaker
And certainly in our guidelines at my center,
00:17:15
Speaker
we are keeping it at two examinations, and we do think that that provides a more meticulous and stringent approach.
00:17:23
Speaker
And in respect to those two exams, obviously it would be different individuals, and would it have to be at a set time difference?
00:17:34
Speaker
Yeah, in adults there is no difference in time.
00:17:38
Speaker
In children, it's six hours that
00:17:41
Speaker
has been mandated that's a bit arbitrary.
00:17:44
Speaker
The most important waiting time between examinations, or let me rephrase that, the most important waiting time is before any evaluations because if you're unsure about the permanence of the situation, you shouldn't be doing any brain death testing in an individual.
00:18:02
Speaker
An intervening waiting period is arbitrary and likely unnecessary.
00:18:08
Speaker
Pediatrics wanted to keep a waiting period, and that's fine.
00:18:11
Speaker
So that's present in children, but there's no specified waiting period in adults.
00:18:17
Speaker
Perfect.
00:18:18
Speaker
Now, you did mention the components of the neurologic examination, and we'll also link our previous conversation that talks about this as well, and that has not changed.
00:18:27
Speaker
I do have a couple of questions, Dave, on this topic, though.
00:18:31
Speaker
And maybe I misunderstood the guidelines, but it almost felt that in terms of the oculocephalic reflex and the oculovestibular reflex,
00:18:41
Speaker
It wasn't an and, but it was you do the oculosephalic, and if you couldn't do that, you can do the oculovestibular.
00:18:49
Speaker
Did I get that wrong?
00:18:51
Speaker
Yeah, I think you did, and I'm sorry if we didn't phrase that as eloquently as we could have.
00:18:57
Speaker
As a general rule, you want to test everything you can in every patient.
00:19:02
Speaker
And so if you can test the oculosephalic and the oculovestibular response, then you do.
00:19:09
Speaker
The only time that you wouldn't do the oculosephalic reflex would be in a patient with cervical spine instability or concern about a skull base issue.
00:19:21
Speaker
And so that's the only part of the test that you can skip, and still do a clinical determination.
00:19:27
Speaker
However, the ocular vestibular
00:19:30
Speaker
you cannot skip and it is felt to be the more potent of the two evaluations to test the middle of the brain stem and only in the in the situation where you're concerned about ototoxicity that it wouldn't be a valid test and you'd have to get an ancillary test but you don't skip these that test at any time unless you have a non-intact tympanic membrane and you're worried about
00:19:56
Speaker
instilling into it and causing an infection because it won't be a clean space.
00:20:02
Speaker
If that's the case and you cannot do ocular vestibular testing, then you're really mandated to get ancillary testing in addition to the complete exam, including the apnea test or tests if it's a pediatric patient.
00:20:14
Speaker
The oculosephalic reflex or the doll's head maneuver, as it is colloquially called, is the only thing that if you cannot test it, you can still do a clinical determination of brain death.
00:20:26
Speaker
And when we say you cannot test it, it's not that it's not coming out as you expect it.
00:20:31
Speaker
You have a cervical injury and you can't manipulate the head, right?
00:20:34
Speaker
Exactly.
00:20:35
Speaker
You're precluded from testing it because of the potential for injuring the patient.
00:20:39
Speaker
Perfect.
00:20:39
Speaker
So the clarification then is all the elements of the clinical exam, assessment of arm responsiveness, assessment of the pupillary light reflex, octrocephalic reflex, ocular vestibular reflex, corneal reflex, gag and cough frequencies must be done.
00:20:56
Speaker
When we have a cervical injury and cannot safely do the oculosephalic reflex, the ocular vestibular reflex by itself will suffice.
00:21:04
Speaker
Okay, perfect.
00:21:05
Speaker
So that is, I think, what I wanted to clarify.
00:21:07
Speaker
Now, you did mention, Dave, the apnea test, and that seems to be obviously a source of...
00:21:14
Speaker
straightforward it looks like on paper but then when people start doing it all all sorts of things pop up right so let's talk about the apnea test and in terms of it if you could just outline in general terms the procedure for performing the apnea test and then we can go into some more details
00:21:33
Speaker
Sure.
00:21:33
Speaker
So the first thing is going to be establishing that the patient is stable enough from a pulmonary standpoint to undergo apnea testing.
00:21:40
Speaker
And so they should be on relatively low settings and something that you could safely take off of the ventilator.
00:21:47
Speaker
If you reduce the patient to 5 and they start to desaturate, that may be a patient that's not able to get through the test safely.
00:21:54
Speaker
Everybody gets pre-oxygenated.
00:21:56
Speaker
We like to get the PaO2 greater than 200.
00:21:59
Speaker
and you want to establish a normal capnea unless they're a CO2 retainer, which I'll get into.
00:22:04
Speaker
You want to establish a normal pH.
00:22:09
Speaker
You want to make sure that they are euvolemic, and this is so important.
00:22:12
Speaker
because many of these patients do develop diabetes insipidus and they may have a negative fluid balance and be very much at risk for getting hypotensive because of their hypovolemia and the acidosis that you're going to cause.
00:22:25
Speaker
So you want to make sure they're euvolemic.
00:22:27
Speaker
And then you make sure that they're normothermic also, and again, they have to have a minimum temperature of at least 36 degrees Celsius.
00:22:34
Speaker
I do recommend disconnecting the patient from the ventilator if you can, because then there's no question of whether a breath came from auto cycling of the ventilator or from the patient.
00:22:46
Speaker
You can do it on CPAP with 100%.
00:22:49
Speaker
O2 going through or with a flow inflating resuscitation bag with a functioning peep valve as well.
00:22:57
Speaker
Those are other ways of doing this in a patient who might be worried about having pulmonary decompensation during the test.
00:23:07
Speaker
Perfect.
00:23:07
Speaker
And you did mention the CO2.
00:23:09
Speaker
So can we talk about the CO2, the baseline required, and the post-apnea test requirements as well?
00:23:16
Speaker
Great.
00:23:16
Speaker
So if they have no history of chronic hypercarbia, then you're going to be aiming for a normal PCO2.
00:23:22
Speaker
However, if they're known to be chronically hypercarbic and you know their baseline level, then the level that you start with should be at the patient's chronic baseline.
00:23:31
Speaker
If they're suspected to have chronic hypercarbia but you don't know their baseline PCO2 level, then it should be at the estimated chronic baseline, but you also have to get ancillary testing in addition in that setting.
00:23:46
Speaker
If they do not have chronic CO2 retention, you're going for the PCO2 level of 60 or greater and 20 above the patient's pre-apnea test baseline.
00:23:58
Speaker
And
00:23:59
Speaker
If they're known to have CO2 retention and you know their baseline PCO2, then you must conclude that the adocyanate test is positive if they have no respirations and the pH goes less than 7.3 and the PCO2 is greater than 60 and 20 above the patient's known elevated premorbid baseline,
00:24:21
Speaker
and again if they are suspected to have chronic CO2 retention but you don't know their baseline level, you're again going for the pH of less than 7.3, the pCO2 of greater than or equal to 60 and 20 above their baseline at the pretest level, and you have to get ancillary testing in addition to that.
00:24:41
Speaker
And this is all spelled out, I think, very clearly in the new guidelines.
00:24:46
Speaker
Absolutely.
00:24:47
Speaker
And the one thing I just wanted to mention also is that if you usually go for 10 minutes, but if at 10 minutes the patient is not having any hemodynamic instability, there is no severe hypoxemia, and you're still not at the threshold that you mentioned for CO2, you can continue and recheck as you go along, correct?
00:25:07
Speaker
Correct.
00:25:08
Speaker
That's absolutely correct.
00:25:09
Speaker
And I like to send ABGs along the way, and hopefully the lab can report them very quickly.
00:25:14
Speaker
But it's also helpful to send it at 5, 8 minutes, etc., because the patient may decompensate later, and if they reach their PCO2 and pH goals, but they didn't breathe, then your test is done.
00:25:27
Speaker
But I've heard of people going for longer, even up to 30 minutes.
00:25:31
Speaker
I've never gone that far.
00:25:33
Speaker
But some patients don't generate a lot of CO2,
00:25:37
Speaker
and so you often can go for longer.
00:25:39
Speaker
But if you're going to repeat the test and go for longer, you again have to reestablish normal capnea, a normal pH, and pre-oxygen activation.
00:25:50
Speaker
I can't emphasize that enough.
00:25:51
Speaker
Perfect.
00:25:52
Speaker
So in terms of recapping, what is required for an apnea test to be consistent with brain death, death by neurologic criteria?
00:26:01
Speaker
Yeah, so I mentioned it a little bit earlier, but regarding...
00:26:05
Speaker
a patient who does not have chronic hypercarbia, you're going for both a pH goal and a PCO2 goal.
00:26:11
Speaker
And the PCO2 goal is at least 60 and 20 above.
00:26:15
Speaker
So previous adult guidelines said or, and we changed that to an and.
00:26:19
Speaker
It always should have been and, in my opinion.
00:26:21
Speaker
And we're making sure that the patient's getting acidotic because it's not just the hypercarbia, but really the acidosis that's triggering the medullary chemoreceptors to trigger a breath.
00:26:32
Speaker
And so those things are now in place.
00:26:35
Speaker
Again, if somebody is a chronic hypercarbic and you know their baseline values, then again they have to go above 60 and 20 above their known baseline level and they don't require an apnea test.
00:26:46
Speaker
If they're suspected to be a CO2 retainer and you don't know their baseline BCO2, then you have to go above 60 and 20 above the baseline value and get an ancillary test in addition in that situation.
00:27:00
Speaker
Perfect.
00:27:00
Speaker
So ultimately, really, what we're looking for is no spontaneously triggered breath under the right conditions, which is not a time-based situation, but a situation based on having a pH below 7.3, a PCO2 above 60, and a PCO2 that's 20 above their baseline when we know the baseline.
00:27:19
Speaker
Yep, that's correct.
00:27:20
Speaker
Perfect.
00:27:21
Speaker
Now, when do you abort or when should you abort a apnea test, which is not the same as a negative or a positive, right?
00:27:29
Speaker
A positive apnea test is consistent with brain death, a negative apnea test, there's spontaneous breathing, and an aborted apnea test is done for safety.
00:27:38
Speaker
When should we do that?
00:27:41
Speaker
Yeah, so there are three conditions where you have to consider aborting the APTAN test.
00:27:44
Speaker
No, number one is going to be regarding their blood pressure.
00:27:47
Speaker
So if the systolic goes less than 100 or the mean arterial pressure goes less than 75 in adults or the SPP and the mean arterial pressure go less than the fifth percentile for age in children, despite the titration of vasopressors, inotropes, or intravenous fluids during the procedure, which you're perfectly allowed to do,
00:28:08
Speaker
Number two would be a progressive decrease in oxygen saturation below 85%.
00:28:13
Speaker
In the old adult guidelines, we said below 85% for 30 seconds.
00:28:18
Speaker
We took out the 30 seconds and we said if they start going to less than 85%, you abort the test then.
00:28:24
Speaker
And the third condition is if you have a cardiac arrhythmia with hemodynamic instability.
00:28:29
Speaker
So patients may have AFib or
00:28:33
Speaker
a flutter and that's okay but if they start to drop their pressure then that's going to be a situation where you have to abort the test.
00:28:41
Speaker
And in these situations, you basically first should always pre-plan to mitigate these, right?
00:28:47
Speaker
So have appropriate fluid loading, have appropriate drugs for blood pressure, that's a concern, have appropriate pre-oxygenation like you mentioned.
00:28:57
Speaker
But if we have to abort, my understanding is that either you try to redo the apnea test when it's safer, if possible,
00:29:07
Speaker
But if not, obviously you now are going to fall in the category of requiring ancillary testing to confirm the diagnosis.
00:29:15
Speaker
Yeah, that's absolutely right.
00:29:16
Speaker
So maybe you can stabilize the patient, but if you're concerned and you can't do it, then you're required to get an ancillary test in that situation.
00:29:24
Speaker
Okay.
00:29:24
Speaker
So before we go to ancillary testing, could you talk a little bit about the apnea test in patients with ECMO?
00:29:31
Speaker
That is an area of interest for obviously our audience, but also I think it's a very unique addition to the guidelines in this iteration.
00:29:41
Speaker
Yeah, it's a great question, and we're so happy that we could provide guidance on ECMO specifically in this, and hopefully we'll provide even more guidance in the years to come.
00:29:50
Speaker
The first principle is pre-oxygenate the patient again.
00:29:53
Speaker
If you don't pre-oxygenate the patient and they get hypoxic, they're almost certainly going to crash during the test.
00:29:59
Speaker
So you want to use 100% FiO2 on the ventilator and through the membrane lung as well.
00:30:06
Speaker
To achieve the adequate increase in the PCO2 level, you titrate exogenous CO2 into the ECMO circuit or adjust the sweep gas flow rate to 0.2 to 1 liter per minute.
00:30:20
Speaker
You sample ABG measurements from both the patient's distal arterial line and the ECMO circuit post-oxygenator for patients on VA ECMO.
00:30:29
Speaker
And the PCO2 and pH levels from both locations
00:30:32
Speaker
are required to meet the criteria for the apnea test to be positive.
00:30:36
Speaker
And this ensures that independent of the mixing point, the PCO2 and the pH levels and the cerebral circulation meet the criteria.
00:30:45
Speaker
For patients on VV ECMO, sample ABG measurements can be only from the patient's distal arterial line, as this will be an appropriate approximation.
00:30:54
Speaker
To avoid hypotension during the test on ECMO, you increase the flow rates, intravenous fluids,
00:31:01
Speaker
or provide vasopressor inotropic support.
00:31:06
Speaker
Perfect.
00:31:07
Speaker
And then the next topic I wanted to ask you about was ancillary testing as part of the BD-DNC evaluation.
00:31:15
Speaker
We did mention several situations, but just to reemphasize, when do we need an ancillary test?
Ancillary Testing and Consent Considerations
00:31:23
Speaker
So number one would be when you have injuries like fractures to the cervical spine, the skull base, or the orbits, or severe facial injuries or swelling or other abnormalities that could preclude an accurate assessment of any components of the neurological exam, with the exception, as I mentioned earlier, to the oculocephalic reflex.
00:31:41
Speaker
or if you have injuries to the cervical spinal cord that limit the adequate assessment of extremity movement or spontaneous respiration, such as if they have a C-spine fracture and you're concerned that they might have a phrenic nerve palsy or inability to move based on a severe spinal cord injury or even a severe peripheral neuropathy, then the ancillary test would be required then.
00:32:06
Speaker
Number two would be if you're unable to perform or complete the apnea test safely because of the patient's risk of cardiopulmonary decompensation or inability to interpret the PCO2 levels in a patient with chronic hypercarbia without a known baseline PCO2 level.
00:32:22
Speaker
Number three would be when you have neurological findings on exam that are difficult to interpret, such as limb movements that may or may not be spinally mediated.
00:32:31
Speaker
If you're unsure and your experts are unsure, then you should get an ancillary test.
00:32:35
Speaker
And number four would be metabolic derangements that are unable to be adequately corrected and you think could be potentially confounding the exam.
00:32:43
Speaker
That would be another situation where you'd be mandated to get an ancillary test.
00:32:48
Speaker
I would like to start first with some problematic ancillary tests, and then we can go into what's currently recommended by the guidelines.
00:32:55
Speaker
But...
00:32:56
Speaker
EEGs and even SEPs, but especially EEGs, are commonly ordered or requested in the evaluation of these patients, yet as an ancillary test, they're kind of problematic.
00:33:10
Speaker
Could you talk about that a little bit, Dave?
00:33:14
Speaker
Yeah, so EEGs were used for many decades and almost certainly should not be used in isolation because
00:33:22
Speaker
There are two problems.
00:33:23
Speaker
One, you can get false positives because the patient, you're not getting any reading of electrical activity in the brainstem.
00:33:31
Speaker
A cortical EEG or a scalp EEG is only going to read the cortical activity.
00:33:36
Speaker
And so remember, the brainstem is the last thing to go in brain death.
00:33:40
Speaker
So
00:33:40
Speaker
in isolation EEG would not be helpful.
00:33:42
Speaker
You could also get false negatives because there's a lot of electromagnetic interference in the ICU setting and actually could show blips on the EEG which are not coming from the patient.
00:33:54
Speaker
FCPs may be helpful for assessing brainstem integrity but remember they only assess the somatosensory pathways and so that's not really telling you about all of the brainstem integrity.
00:34:05
Speaker
So
00:34:06
Speaker
Electrical tests such as EEG and SACP have really fallen out of favor and now have been removed from the guidelines in the most recent iteration as an acceptable test.
00:34:17
Speaker
What are tests that are accepted in the guidelines right now and what should we be considering for ancillary tests when they're indicated?
00:34:24
Speaker
Yeah, so there are really three and they're all flow-based.
00:34:26
Speaker
So the first one is the gold standard, which is a catheter angiogram where you inject under pressure into the carotid and the vertebral circulation.
00:34:35
Speaker
And you're looking for any
00:34:36
Speaker
flow as the vessels pierce the dura to show that it's getting any effective forward intracerebral flow.
00:34:45
Speaker
Transcranial Doppler is a useful test as well.
00:34:48
Speaker
It's the only one that's really portable and that can be very helpful for patients who are too unstable to go for a different ancillary test.
00:34:57
Speaker
It's technically challenging.
00:34:59
Speaker
We don't accept the absence of flow signal.
00:35:02
Speaker
You really actually have to see
00:35:04
Speaker
reverberating flow where the flow goes to zero or negative numbers in diastole, which tells you that the ICP is higher than the mean arterial pressure.
00:35:14
Speaker
The test has to be done twice.
00:35:16
Speaker
It has to be done both anteriorly and posteriorly, and it has to be separated by at least 30 minutes between the tests, and it can be technically challenging.
00:35:26
Speaker
The third is going to be a spec study or nuclear medicine radionuclide study.
00:35:31
Speaker
This is using a tracer to look for cerebral perfusion.
00:35:36
Speaker
We prefer lipophilic agents because a lipophilic agent will not just show you tracer within the vasculature, but also in metabolically active tissue, so it's felt to be a more sensitive test to look for cerebral viability.
00:35:51
Speaker
This again requires transport, but it's probably the most commonly used test and should be considered highly reliable.
00:36:00
Speaker
Any comments on CTA, MRA technology, which I think some people have also proposed?
00:36:08
Speaker
Yeah, so people would love to use CTA and MRA, and I'm in that camp.
00:36:12
Speaker
I'd love to use that as well.
00:36:14
Speaker
The problem is they haven't been validated, and remember that the difference between a catheter angiogram and a CT angiogram is that the CT angiogram is a venous injection, and we don't know what the proper timing is to know when a patient has had
00:36:31
Speaker
adequate observation of their cerebral vasculature to say that there is no forward flow.
00:36:37
Speaker
Whereas if you're doing a dynamic angiogram under pressure, you can tell that there's no flow going angiocranially.
00:36:43
Speaker
So that's considered a much more viable test.
00:36:45
Speaker
We would love to validate CTA against a more standard or gold standard
00:36:54
Speaker
circulatory tests and that's ongoing work that we're doing now.
00:36:58
Speaker
But for now, I mean, we stick with the ones that you mentioned.
00:37:01
Speaker
And the last question I have on ancillary testing is if you have met all the criteria for prerequisites, you have imaging that supports a catastrophic injury and etiology, all the elements of the test are inequivocally consistent with brain death, you do the apnea test, do you need an ancillary test?
00:37:24
Speaker
Now, if you can test everything that is testable, with the exception, again, of the oculosephalic, and there's no confounders, you do not need to get an ancillary test.
00:37:34
Speaker
It's only when you cannot fully perform all the clinical testing or safely perform all the clinical testing or eliminate confounding.
00:37:42
Speaker
Those are your circumstances.
00:37:45
Speaker
Perfect.
00:37:45
Speaker
So it's not a requirement when we can meet all the other criteria, which in some places I think people always feel that they have to have that.
00:37:52
Speaker
And like you mentioned, I mean, it has a place, which is important.
00:37:57
Speaker
But if you can meet all the criteria, you can definitely determine death by another criteria with those.
00:38:03
Speaker
Perfect.
00:38:05
Speaker
Yeah, I actually worry more about places where they go straight to ancillary testing, and I've seen that happen where they'll get a spec just to see if the patient is brain dead, and I think that's a really dangerous practice.
00:38:16
Speaker
I think the clinical testing should always be
00:38:19
Speaker
paramount in the way that people determine unless they absolutely have to get an ancillary test.
00:38:24
Speaker
So that's a strong emphasis for us.
00:38:26
Speaker
Perfect.
00:38:27
Speaker
Now let's talk about some special considerations.
00:38:30
Speaker
You did mention at the beginning of our conversation, Dave, the concept of consent.
00:38:36
Speaker
Do we need to consent families, because we can't consent the patient, obviously, for undergoing this evaluation?
00:38:42
Speaker
How does that work, and what's the thought of the guidelines?
00:38:46
Speaker
Yeah, so, I mean, there's been a bit of back and forth pro-con debate about getting consent for brain death testing.
00:38:52
Speaker
And we stay consistent in the guidelines by saying consent is not required.
00:38:57
Speaker
This is not a procedure that carries a risk to the patient.
00:39:01
Speaker
If you think that the patient is not potentially brain dead, you should not be testing the patient for brain death.
00:39:08
Speaker
The pre-test probability should be very, very high when you're doing this.
00:39:13
Speaker
There has not been
00:39:16
Speaker
a good argument made to require consent for this.
00:39:21
Speaker
It's a medical diagnosis like any other.
00:39:23
Speaker
We would not require consent to declare somebody dead by cardiopulmonary means and thus this is no different and we remain consistent with prior guidelines in that regard.
00:39:35
Speaker
When we complete this process evaluation for brain death and death-pagnudial criteria, and we determine that the patient, the exam is consistent with this, and we need to pronounce the patient, what's the time of death?
Family Discussions and Organ Donation
00:39:51
Speaker
So the time of death, if you determine them clinically without an ancillary test, is going to be the time that the ABG is reported by the lab,
00:39:59
Speaker
and that those values have reached the criteria.
00:40:02
Speaker
If it's an ancillary test, it's the time that the attending physician signs the report.
00:40:07
Speaker
Those are the time of death for both adult and pediatrics.
00:40:12
Speaker
And once we have that time of death, what is the current thought process or recommendation of the guidelines in terms of how do we proceed from there?
00:40:22
Speaker
I think that there's obviously an area where, okay, the patient's brain dead, but it's not as soon as we have all that without conversing with families, we just take the patient off life support.
00:40:34
Speaker
How do you deal with that?
00:40:37
Speaker
Yeah, so, well, first of all, that shouldn't be your first conversation you're having with the family is to tell them that their loved one is dead by brain criteria.
00:40:43
Speaker
I think that can be very confusing for them.
00:40:45
Speaker
So it's important to have a conversation with them and say that the patient has had a neurological catastrophe.
00:40:51
Speaker
You're very concerned that they may have brain death or may progress to brain death.
00:40:55
Speaker
And here's what that means, and here's the type of testing that we'll be doing.
00:40:59
Speaker
I also like for families to be able to be there when I do the testing, both the clinical exam and the apnea test, because that can be very helpful for them to really see and see for themselves that their loved one isn't breathing for 10 minutes off a ventilator.
00:41:13
Speaker
That's very, very powerful for them.
00:41:15
Speaker
When you have the conversation, I do say that your loved one has died, and their time of death was
00:41:21
Speaker
You know, 10.53 a.m.
00:41:24
Speaker
or p.m.
00:41:25
Speaker
I think that's helpful for people to have that finality.
00:41:28
Speaker
I do know that organ donation is a potential for our patients, but I also know that we need to decouple that conversation.
00:41:36
Speaker
So I've been having conversations with my OPO along the way to see if the patient is a potential candidate and then try to have a way to introduce them to the family once the family has come to terms.
00:41:48
Speaker
with the diagnosis and typically it's in the same conversation and families are very willing to listen, but we give them the opportunity to hear about the potential for Ergon donation and see what next steps would follow after that.
Pregnancy Considerations in Brain Death
00:42:08
Speaker
I wanted also to ask you as we wrap up the conversation on some of these special patient populations, and you did mention pregnancy.
00:42:17
Speaker
Pregnancy in the ICU is always a very difficult topic because obviously there's more than one life at danger.
00:42:24
Speaker
But could you talk about the evaluation, determination of BD, DNC, and pregnant patients and some of the aspects that the guidelines have discussed?
00:42:37
Speaker
Sure.
00:42:37
Speaker
So remember the pregnancy in and of itself is not a contraindication to brain death evaluation.
00:42:42
Speaker
And just like any other patient, clinicians should diagnose pregnant persons with a catastrophic permanent brain injury for brain death or death by neurological criteria.
00:42:55
Speaker
In that process, however, you want to make sure you're getting
00:42:58
Speaker
other clinicians involved, including maternal fetal medicine, child neurology, neonatology, to educate and discuss with surrogate decision makers regarding the risks and benefits of the fetus to continuing maternal organ support in that situation.
00:43:16
Speaker
That can be challenging, but certainly has been done.
00:43:18
Speaker
It depends on a lot of factors, including the stability of the
00:43:22
Speaker
the mother, but also how far along the pregnancy is.
00:43:25
Speaker
We didn't get into that kind of detail.
00:43:27
Speaker
It's really a matter of getting your experts involved to see what is the likelihood in an individual patient given the physiology of the mother and the viability of the fetus.
00:43:38
Speaker
So that's some new guidance that we provided in this guideline.
00:43:44
Speaker
And obviously there's been some reported cases of brain dead or pregnant patients in whom support was continued a little bit longer to try to get the fetus to term.
00:43:56
Speaker
And again, like you said, that is a granular, very specific case that should be discussed at the level with the maternal fetal experts and the whole team.
00:44:10
Speaker
That's correct.
00:44:11
Speaker
That's the way to approach it at this point.
Supratentorial Injury Confirmation
00:44:13
Speaker
Could you talk about the primary posterior fossa injury patients and why this is important, especially for our non-neurology crowd?
00:44:21
Speaker
Sure.
00:44:23
Speaker
So...
00:44:24
Speaker
When you have a patient who's had a brainstem catastrophe, let's say a massive bleed in their brainstem, they could look comatose.
00:44:32
Speaker
They could have brainstem areflexia.
00:44:35
Speaker
They could even be apneic during PCO2 and acidotic challenge.
00:44:40
Speaker
However, they may still have circulation to their cerebral cortex up above.
00:44:47
Speaker
And so it's important to make sure that you've got
00:44:50
Speaker
at least in the U.S., evidence of catastrophic injury to the supratentorial structures also.
00:44:56
Speaker
That is typically in the setting of a patient who develops hydrocephalus from their posterior fossa injury and is not treated because the neurosurgeons appropriately say that there's no indication for the
00:45:12
Speaker
the ventriculostomy because of the patient's overall prognosis it would be deemed futile.
00:45:17
Speaker
So if a patient then develops massive hydrocephalus and their ICP is presumably extremely high, they're going to get secondary ischemic injury and catastrophic supratentorial injury as well.
00:45:31
Speaker
So we're really emphasizing the quote whole brain formulation of brain death and you really need to have
00:45:39
Speaker
conventional neuroimaging, meaning a CT or an MRI that shows supratentorial injury in addition to infratentorial before initiating a brain death evaluation.
00:45:54
Speaker
Are there any other topics that we should cover as we wrap up regarding to the guidelines?
00:46:03
Speaker
No, I think you've covered it.
00:46:04
Speaker
Again, it's a very lengthy document, and I apologize for that, but we wanted it to be very thorough.
00:46:11
Speaker
We think the tables are very helpful.
00:46:13
Speaker
We want you to have meticulous attention to technique, which we really spell out in the tables also, so please use that.
00:46:21
Speaker
And then we are updating the Neurocritical Care Society.
00:46:25
Speaker
toolkit with a lot of new resources and providing great guidance through that mechanism as well.
00:46:32
Speaker
So you have a lot of tools to do this correctly.
00:46:35
Speaker
This is really one of those diagnoses in medicine where we have to get it right 100% of the time.
Care with Dignity and the Joy of Medicine
00:46:41
Speaker
And so please educate yourselves adequately so you feel comfortable in the clinical setting.
00:46:47
Speaker
Well, thanks, Dave, for sharing all that and for all the work you've done in this area that is not only extremely important, but I think really is quite fascinating, right?
00:46:59
Speaker
The whole concept of at what point does life really stop is something that for many years has kept me in awe at the bedside because definitely we have to make some arbitrary decisions.
00:47:11
Speaker
But it's just, I mean, it's something that's full of wonder and unanswered questions.
00:47:19
Speaker
But I would like to close the podcast with asking you some questions that are unrelated to the clinical topic.
00:47:25
Speaker
You've been on the podcast before, so you know how it works.
00:47:28
Speaker
Would that be okay?
00:47:30
Speaker
Of course.
00:47:31
Speaker
Any books that you have recently read that have influenced you significantly or that you have gifted to others?
00:47:39
Speaker
Well, the book I love to gift and re-gift is called Boys in the Boat, which is a story of the University of Washington rowing team from the 1930s.
00:47:49
Speaker
It's a it's a terrifically written book and very inspirational.
00:47:52
Speaker
I love team of rivals by Doris Kearns good good one on Abraham Lincoln and his cabinet and I really love
00:48:01
Speaker
anything by J.D.
00:48:02
Speaker
Salinger.
00:48:03
Speaker
I'm very old school, and so he put anything by J.D.
00:48:05
Speaker
Salinger in front of me, and I'll read it for sure.
00:48:08
Speaker
Perfect.
00:48:09
Speaker
So all of these, I mean, obviously great, great reads, and we'll link them in the show notes.
00:48:14
Speaker
The second question relates to beliefs.
00:48:16
Speaker
What do you believe to be true in medicine or life that many other people or most people don't believe or don't act like they believe?
00:48:24
Speaker
Well, I don't know if other people don't believe this, but one thing I've come to realize in the age of wellness and
00:48:30
Speaker
work-life balance is that I think the key to wellness in medicine is finding joy in your daily work.
00:48:36
Speaker
That what we get to do on a daily basis, whether it's clinical research or education, it's really beautiful.
00:48:42
Speaker
And many people in their careers don't get this kind of joy.
00:48:46
Speaker
And so rather than focusing on the negatives, I like to focus on the positives.
00:48:50
Speaker
And I think that I'm a big student of stoic philosophy and a big believer in focusing on what I do control, not to dismiss the external pressures and problems that healthcare has created that impact our wellness, but I do believe that finding joy is an internal choice and one that a lot of us have accessible, and we should definitely, I mean, work on it because I do agree it does a...
00:49:18
Speaker
help your well-being significantly.
00:49:23
Speaker
What would you want every intensivist listening to us, every APP listening to know?
00:49:28
Speaker
Could be a quote, a fact, or just a thought to close.
00:49:32
Speaker
Yeah, so in the neuro ICU, we deal with a lot of death and destruction all the time.
00:49:36
Speaker
And what I'd emphasize is that you're able to really help every patient and family regardless of the outcome.
00:49:42
Speaker
Given that many of our patients die in intensive care,
00:49:45
Speaker
we shouldn't only celebrate the saves, but also the good deaths or patients who die with dignity and peace.
00:49:51
Speaker
So you can't save everyone.
00:49:53
Speaker
And sometimes it's just people's time.
00:49:54
Speaker
And I think that allowing a patient to pass on with peace and dignity can be a beautiful thing and very helpful for families.
00:50:02
Speaker
I think this is as
00:50:03
Speaker
important a skill and an intensivist as any other.
00:50:07
Speaker
And I think this is a perfect place to stop.
00:50:09
Speaker
Dave, once again, thank you for all the work you've done in this area of neurocritical care, brain death, and DNC.
00:50:18
Speaker
Very happy to have you share your expertise with our audience and hope to have you back to talk about this and other topics.
00:50:24
Speaker
It was my pleasure.
00:50:25
Speaker
Thank you, Sergio.
00:50:26
Speaker
Thank you for listening to Critical Matters, a sound podcast.
00:50:30
Speaker
Make sure to subscribe to Critical Matters on Apple or Google Podcasts and share with your network.
00:50:36
Speaker
Sound's transforming the way critical care is provided in hospitals across the country.
00:50:40
Speaker
To learn more, visit www.soundphysicians.com.