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Ep2: Brain Death Testing | Apnea Testing

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This podcast covers the basics behind brain death testing.  Apnea testing as well as tests for the various cranial nerves.  We also touch on the difference between coma, vegatative state, and actual brain death.

NIH Brain Death Website

CNN Article About Brain Death

PODCAST TRANSCRIPT:

Hey everybody. This is Jon with NRSNG.com. Today I wanted to just talk really briefly about brain death testing and exactly why it’s done, what it is and how kind of some of the practices that are used within neuro ICUs nowadays to determine brain death.

 

Now as always, this podcast is not giving medical advice or anything like that. Just kind of sharing some of the experiences that I’ve seen throughout my career in neuro ICU as well as some of the guidelines by the National Institute of Health. You shouldn’t use this podcast to make any medical decisions or anything like that.

 

So first of all, why do we do brain death testing? Well, there are basically two ways that a person can die essentially. It’s cardiac death and brain death. If the heart stops perfusing the body, the body stops getting oxygen and the patient will die.

 

If the brain stops being perfused, stops working, then the person also will die. This one is a little bit harder for patients and patient’s families to understand.

 

But there is a big difference between brain death and coma. It can be really hard for patients to understand this. So it’s important that as people come in and you talk with families and things, that you distinguish that there is really a difference between brain death and coma and persistent vegetative state and things like that.

 

So there’s really a very basic article on CNN.com and we will link to it. This article came out in January of 2014 with the whole fiasco of Jahi McMath, the 13-year-old girl who was declared brain dead, and of course the family is thinking that she is not actually dead. But according to brain death testing and things like that, the patient has been declared dead.

 

So there’s a really good article. It’s kind of written at a level that is very understandable. I will go ahead and link to that in the show notes and on the blog in NRSNG.com/003.

 

So it’s really important that the people understand that when someone is declared brain dead, that the – all sense of neurological function has been stopped.

 

The brain has not been perfused. The brain is not capable of functioning and the patient is actually no longer considered alive by medical standards.

 

Coma is different. Coma, there’s still brain function. There’s still brain stem function. It’s just the patient is not alert, awake and arousable.

 

Persistent vegetative state, same thing. I mean you still have neurological function. It’s just severely depressed.

 

So let’s go ahead and talk about how is brain death determined. So brain death needs to be determined by a physician who’s trained and experienced in assessing brain death.

 

What we’re trying to do is to determine that there is no brain function. There’s no brain stem function and that can be done through the series of a few tests.

 

First of all, the physician should come in and physically assess the patient and that will hopefully have been done throughout the course of the patient’s stay and the neurologist will come in and assess the patient and determine their diagnosis.

 

So first the physician comes and examines the patient. They’re going to want to check a few things to see that the patient is – has lost brain stem reflexes and they’re going to check cranial nerves.

 

So first of all, they’re going to assess the pupils generally. They’re going to want to determine that there is no response to light, that the pupils are not responding to any sort of light, and that’s going to determine that there is an absent of light reflex.

 

So basically they will just open the patient’s eyes, shine a light, determine that they are not responding. That’s going to test cranial nerves two and three.

 

Some physicians will do this. I’ve seen some do it and they will actually test the ocular movement and it’s going to test cranial nerves three, six and eight.

 

They’re going to actually instill a bit of cold water into the ear canal and see if the eyes either deviate from the cold water or not. If there’s cranial nerve function within those cranial nerves mentioned, three, six and eight, then the eyes will actually deviate away from that. If they do not, then those determine that those cranial nerves are not functioning.

 

Then you’re also going to make sure that there is no facial sensation or facial motor response and assess the face, assess for corneal reflex. That’s cranial nerves five and seven.

 

They’re going to make sure there is no grimacing under deep pressure and the nurse will be doing this generally every hour, every two hours anyway. As they start to see that there is no response to deep pain, then they will start reporting those types of things to the physician.

 

So you’re going to – that’s going to assess cranial nerves five and seven and you’re going to apply deep pressure to the nail beds and you will determine if the patient grimaces or withdraws in any way.

 

You’re also going to assess gag reflex and this is going to check for cranial nerve nine and ten. So you’re going to – usually the patient will be intubated. You can use the inline suctioning kit and press it or insert it completely and see if the patient coughs or gags in any way.

 

If they do not cough or gag, then you’re going to say that they have absent cough reflex. So as the patient starts to lose these reflexes, we’re determining that these cranial nerves are no longer functioning and we can move on with our testing.

 

Now this is – all of these things are part of a basic neurological examination that the bedside nurse should be doing every couple of hours. As they start seeing these things disappear, these reflexes disappear, then they need to be reporting those to the neurologist, to the hospitalist, and let them know that we are progressing toward brain death.

 

So once we get those things determined, we’re going to kind of move on to what’s called apnea test. Now that new test is a neat little test. It’s going to determine if the patient is capable of taking a spontaneous breath on their own in the presence of hypercarbia. So we’re going to try to drive up the CO2 level within their body and see if the patient takes any sort of breath on their own.

 

Now our sensation to – our drive to breathe is a brain stem reflex and so if we have that absent ability to take a breath under hypercarbia, then we can determine that we have brain stem damage to the point that the patient will not breathe on their own, no matter what.

 

So what we do is we take the patient and we get their blood gas in an appropriate range and we kind of hyper-oxygenate them, get them in an appropriate blood gas range. Then we turn off the ventilator and we keep it off for about 10 minutes. It’s generally what will happen and during those 10 minutes, we watch their vital signs and see if there’s any increase in blood pressure, increase in heart rate, see if they’re stressed at all by having the ventilator off.

 

We will watch to see if they’re breathing. Watch very closely. We sit there at the bedside for 10 minutes or so and determine if there is any sort of sign of breathing. Now to be absolutely positive that there was no breath initiated by the patient spontaneously, at the end of these 10 minutes, we will draw blood gas.

 

What we’re trying to do is determine OK, we drove up their CO2 drastically and that’s generally our motivation to breathe is that as the CO2 rises, our brain stem signals to our body that it’s time to take a breath.

 

If that doesn’t happen, if we don’t take a breath during that time, then our CO2 will continue to rise and to rise and to rise. So we keep the ventilator off for about those 10 minutes. See if the patient takes a breath to determine. We watch, watch vital signs, watch the patient, see if they take a breath. To verify that no breath was taken and if they did not try to compensate for this hypercarbia, we take a blood gas and if the CO2 is greater than 60 or so, we can determine that they’ve lost that brain stem function to breathe.

 

Generally in these patients, you will see CO2 is 70, 80, even higher, as they do not attempt any spontaneous breaths on their own.

 

So now we checked our cranial nerves. Now we checked our brain stem function. So we can kind of move on to the next test.

Podcast Transcription

Hey, everybody! This is Jon at NRSNG.com.

Today I wanted to just talk really briefly about brain death testing – exactly why it’s done,

what it is and how some of the practices that are used within Neural ICUs nowadays to

determine brain death.

As always this podcast is not giving medical advice or anything like that, just sharing

some of the experiences that I’ve seen throughout my career in Neural ICU as well as

some of the guidelines by the National Institute of Health. You shouldn’t use this podcast

to use any medical decisions or anything like that.

So first of all, why do we do brain death testing? Well, there’s basically two ways that a

person can die, essentially – cardiac death and brain death. If the heart stops perfuse in

the body, the body stops getting oxygen and the patient will die. If the brain stops being

perfuse, stops working, then the person will also die. This one is a little bit harder for

patients and patient’s families to understand but there is a big difference between brain

death and coma. It can be really hard for patients to understand this. So it’s important

that as people come in and you talk with families and things that you distinguish that

there is really a difference between brain death and coma and persistent vegetative

state and things like that. So there’s really a very basic article on CNN.com and we’ll link

to it. This article came out in January 2014 with the whole fiasco of Jahi McMath, the 13-

year-old girl who was declared brain dead and of course, the family is taking that she is

not actually dead but according to brain death testing and things like that, the patient has

been declared dead. So there’s a really good article; it’s written at a level that is very

understandable and I’ll have a link to that in the show notes and on the blog in

NRSNG.com/003.

So it’s really important that people understand that when someone is declared brain

dead that all sense of neurological function has been stopped. The brain is not being

perfuse, the brain is not capable of functioning and the patient is actually no longer

considered alive by medical standards. Coma is different – coma there is still brain

function, there’s still brainstem function, it’s just the patient is not alert, awake and

arousable. Persistent vegetative state is the same thing – you still have neurological

function it’s just severely depressed.

Let’s go ahead and talk about how is brain death determined? Brain death needs to be

determined by a physician who is trained and experienced in assessing brain death. And

what we’re trying to do is determine that there is no brain function, there is no brainstem

function and that can be done through the series of a few tests.

First of all, the physician should come in and physically assess the patient and that will

hopefully have been done throughout the course of the patient’s stay and the neurologist

will come in and assess the patient and determine their diagnosis. So first the physician

comes, examines the patient and they’re going to want to check a few things to see that

the patient has lost brainstem reflexes and they’re going to check cranial nerves. First of

all, they’re going to assess the pupils generally and then we want to determine that there

is no response to light – the pupils are not responding to any sort of light and that’s going

to determine that there is an absent light reflex. So basically they’ll just open the

patient’s eyes, shine a light, determine that they are not responding. That’s going to test

cranial nerves 2 and 3. Some physicians will do this; I’ve seen some do it and they’ll

actually test the ocular movement and that’s going to test cranial nerves 3, 6 and 8. And

they’re going to actually instill a bit of cold water into the ear canal and see if the eyes

either deviate from the cold water or not. If there’s cranial nerve function within those

cranial nerves mentioned (3, 6 and 8), then the eyes will actually deviate from that. If

they do not, then it is determined that those cranial nerves are not functioning.

Then you’re also going to make sure that there’s no facial sensation or facial motor

response. Assess the face, asses for corneal reflex, that’s cranial nerves 5 and 7. You’re

going to make sure there is no grimacing under deep pressure. The nurse will be doing

this generally every hour or every two hours anyway, and as they start to see that there

is no response to deep pain, then they will start reporting those types of things to the

physicians. So that’s going to assess cranial nerves 5 and 7. And you’re going to apply

deep pressure to the nail beds and you’ll determine if the patient grimaces or withdraws

in any way.

Then you’re also going to assess gag reflex, and this is going to check for cranial nerve

9 and 10. Usually, the patient will be intubated – you can use the inline suctioning kit and

press it or insert it completely and see if the patient coughs or gags in any way. If they

do not cough or gag then you’re certainly going to say that they have absent cough

reflex.

So as a patient starts to lose these reflexes we’re determining that these cranial nerves

are no longer functioning and we can move on with our testing. Now all of these things

are part of a basic neurological examination that the bedside nurse should be doing

every couple of hours. As they start seeing these things disappear, these reflexes

disappear, then they need to be reported to the neurologist or the hospitalist and let

them know that we are progressing toward brain death.

Once we get those things determined, we’re going to move on to what’s called the

Apnea test. The Apnea test is a neat little test. It’s going to determine if the patient is

capable of taking a spontaneous breath on their own in the presence of hypercarbia. So

we’re going to try to drive up the CO2 level within their body and see if the patient takes

any sort of breath on their own. Our drive to breathe is a brainstem reflex, so if we have

that absent ability to take a breath under hypercarbia, then we can determine that we

have brain stem damage to the point that the patient will not breathe on their own no

matter what.

What we do is we take their patient and we get their blood gas come in at an appropriate

range and we hyperoxygenate them; get them in an appropriate blood gas range. And

then we turn off the ventilator and we keep it off for about 10 minutes, is generally what

would happen. During those 10 minutes, we watch their vital signs and see if there is

any increase in blood pressure, increase in heart rate, see if they’re stressed at all by

having the ventilator off. We’ll watch to see if they’re breathing- watch very closely; we

sit there at the bedside for 10 minutes or so and determine if there is any sort of sign of

breathing. To be absolutely positive that there was no breath initiated by the patient

spontaneously, at the end of these 10 minutes we’ll draw blood gas. What we’re trying to

do is determine, okay, we drove up their CO2 drastically, and that’s generally our

motivation to breathe is that, as the CO2 rises, our brainstem signals to our body that it’s

time to take a breath. And if that doesn’t happen, if we don’t take a breath during that

time, then our CO2 will continue to rise, and to rise, and to rise. So we keep the

ventilator of about those 10 minutes, see if the patient takes a breath. To determine we

watch, watch vital signs, watch the patient, see if they take a breath. But to verify that no

breath was taken and that they did not try to compensate for this hypercarbia we take a

blood gas and if the CO2 is greater than 60 or so, we can determine that they’ve lost that

brainstem function to breathe. In general, in these patients, you’ll see 70, 80 even higher

as they do not attempt any spontaneous breaths on their own.

Now we’ve checked our cranial nerves, now we’ve checked our brainstem function and

so we can kind of move on to the next test. And for the next test, we actually want to do

a brain scan to see if there is any blood flow at all to the brain. To do this, there are a

couple different options; what is used most often is this nuclear brain scan. What will

happen is you will take the patient down to radiology and they’ll have an isotope dye

injected into them and what that will do is it will be taken up into the blood vessels and

delivered throughout the body. And as you take a scan of the patient you’ll be able to

see this delivered on the scan; any area that’s taking up this injection will be white and

clear on the scan. Areas that are not taking up this dye will actually be dark and black.

So what you’ll see on the scans of these patients is you’ll see white all the way up the

entire body and it will stop at about the neck. And from about the neck by the brainstem

up, it’s completely black inside. This is called the hollow skull phenomenon and it’s

basically indicating to the physician that the brain is not taking up any of this blood – the

brain is not being perfuse.

So with those things in hand, the physician can generally use those to make a diagnosis

of brain death. This time, you’ll let the family know and the physician will talk to the

family and determine that the patient has died and at that point, the ventilator can be

disconnected and you’ll wait for the heart to stop beating. At that point, the patient is

then taken down and that is how brain death is generally determined. Now we can go

over later on some of the causes of brain death and things like that. Usually, it’s

herniation and as the brain swells and pushes through, the foramen magnum and

different areas. There are different types of herniation but that’s generally what would

cause this brain death that we see in neurological ICUs.

So that’s kind of how brain death testing is done. It’s a pretty interesting series of event

to kind of watch as a physician does this and as you talk with the family and as you try to

comfort them. That’s generally where your nursing care comes into play is being able to

appropriately discuss with the family what’s actually going on with their loved one and

being able to explain to them what brain death is, how it differs from coma, and how it

differs from cardiac death and being able to help them understand this and grasp what’s

actually going on and why these different tests are happening.

So that’s kind of what goes on here with brain death testing. Again, this is Jon with the

NRSNG.com, thanks for listening.

Date Published - Oct 24, 2014
Date Modified - Jul 21, 2016

Jon Haws RN

Written by Jon Haws RN

Jon Haws RN began his nursing career at a Level I Trauma ICU in DFW working as a code team nurse, charge nurse, and preceptor. Frustrated with the nursing education process, Jon started NRSNG in 2014 with a desire to provide tools and confidence to nursing students around the globe. When he's not busting out content for NRSNG, Jon enjoys spending time with his two kids and wife.