Neurogenic Shock | Shock (Part 7)

Summary

This educational video, presented by Eddie Watson, delves into neurogenic shock, a type of distributive shock resulting from CNS injury, typically at T6 or higher spinal cord levels. It explains the lack of sympathetic response leading to decreased blood pressure, heart rate, and cardiac output. The video outlines key signs like hypotension, bradycardia, and hypothermia with warm extremities, emphasizing the importance of ruling out other shock causes. Treatment involves protecting the spine, IV fluids, vasopressors, inotropes, and possibly pacing to increase heart rate. It also stresses maintaining a higher mean arterial pressure for spinal cord perfusion and protecting the airway due to potential respiratory failure, offering a comprehensive guide for medical professionals.

Takeaways

• 🧠 Neurogenic shock is a type of distributive shock resulting from CNS injury, typically involving the cervical or high thoracic spinal cord (T6 level or higher).
• 🚫 The injury leads to an impact on sympathetic nerve outflow, causing a lack of sympathetic response while the parasympathetic response remains active.
• 🌡️ In neurogenic shock, there's a decrease in systemic vascular resistance and blood pressure due to the absence of catecholamines that normally cause vasoconstriction.
• 💓 The sympathetic nervous system's absence also affects the heart, leading to decreased cardiac contraction and preload, contributing to reduced cardiac output.
• 🐦 A characteristic sign of neurogenic shock is a low heart rate due to the lack of sympathetic innervation of the SA node.
• 🌡️ Hypothermia can occur in neurogenic shock, but it is central, meaning the patient's core temperature drops due to hypothalamic dysregulation, not peripheral vasoconstriction.
• 📋 Diagnosing neurogenic shock requires ruling out all other possible causes of shock to ensure accuracy.
• 🩺 Key signs of neurogenic shock include decreased blood pressure, bradycardia, decreased cardiac output, and warm, dry extremities despite hypothermia.
• 🛑 Initial treatment involves protecting the spine to prevent further damage, using measures like a flat bed, c-collar, and log rolling.
• 💧 The first line of treatment for neurogenic shock is IV fluids to replace intravascular volume and counteract the effects of decreased vascular tone.
• 💊 If hypotension persists, vasopressors and inotropes may be used to induce vasoconstriction and improve cardiac contractility, respectively.
• 🔁 For significant bradycardia, medications like dopamine and atropine, or pacing, may be considered to increase heart rate and counteract the parasympathetic response.

Q & A

What is the main focus of the seventh lesson in the series?

The seventh lesson focuses on neurogenic shock, a type of distributive shock, and its various aspects including its causes, effects, diagnosis, and treatment.

What does the term 'neurogenic shock' refer to?

Neurogenic shock refers to a state of shock that results from an injury to the central nervous system (CNS), particularly involving the brain and spinal cord.

What is the role of the sympathetic nervous system in neurogenic shock?

In neurogenic shock, there is an impact on the sympathetic nerve outflow, leading to a lack of sympathetic response while the parasympathetic response remains preserved.

How does neurogenic shock affect coronary blood vessels?

In neurogenic shock, the lack of sympathetic response means there is no dilation of the coronary blood flow that normally occurs during the fight-or-flight response.

What is the impact of neurogenic shock on systemic vascular resistance?

Neurogenic shock leads to a decrease in systemic vascular resistance, which contributes to a decrease in blood pressure due to the lack of sympathetic activation.

Why does neurogenic shock result in decreased cardiac contraction?

The sympathetic nervous system normally has a positive inotropic effect on the heart. In neurogenic shock, the absence of this sympathetic activation results in decreased cardiac contraction.

What is the significance of the SA node in neurogenic shock?

The SA node, or the sinoatrial node, is responsible for controlling the heart rate. In neurogenic shock, the lack of sympathetic innervation to the SA node results in a low heart rate.

Why is hypothermia a potential symptom in neurogenic shock?

Hypothermia can occur in neurogenic shock due to dysregulation within the hypothalamus, which is responsible for body temperature regulation. The lack of sympathetic response also prevents the typical vasoconstriction that leads to cool, clammy skin.

What is the primary treatment for neurogenic shock?

The primary treatment for neurogenic shock includes protecting the spine, administering IV fluids to replace intravascular volume, and using vasopressors and inotropes if necessary.

How does treatment for neurogenic shock differ from other types of shock?

Treatment for neurogenic shock focuses on maintaining a higher mean arterial pressure to ensure adequate spinal cord perfusion, protecting the airway, and managing bradycardia, which are specific considerations due to the CNS injury.

What is the importance of ruling out other causes of shock before diagnosing neurogenic shock?

It is crucial to rule out other causes of shock to ensure an accurate diagnosis and appropriate treatment. Neurogenic shock has specific treatments and considerations that differ from other shock states.

Outlines

00:00

🧠 Understanding Neurogenic Shock

This paragraph introduces the concept of neurogenic shock, a type of distributive shock resulting from central nervous system (CNS) injury, typically involving the brain or spinal cord above the T6 level. The presenter, Eddie Watson, explains how such injuries can disrupt sympathetic nerve outflow, leading to a lack of sympathetic response but a preserved parasympathetic one. This disruption impacts coronary vessels, decreases systemic vascular resistance, and affects cardiac function, resulting in low blood pressure. The absence of sympathetic innervation to the heart leads to decreased contractility and heart rate, contributing to the shock state. Additionally, neurogenic shock can cause hypothermia due to dysregulation in the hypothalamus, but unlike other shock states, the patient's extremities are warm and dry. The importance of ruling out other shock causes before diagnosing neurogenic shock is emphasized.

05:02

🚑 Signs and Treatment of Neurogenic Shock

The second paragraph delves into the clinical signs of neurogenic shock, which include decreased blood pressure due to reduced systemic vascular resistance, and a distinctive lack of compensatory sympathetic response, leading to bradycardia. Other signs include decreased cardiac output, reduced central venous pressure (CVP), and hypothermia with warm, dry extremities. The treatment approach for neurogenic shock is discussed, starting with spinal protection to prevent further damage. Initial treatment involves IV fluids to restore intravascular volume, followed by vasopressors if hypotension persists. Inotropes may be used to improve cardiac contractility, and medications like dopamine or atropine can be considered to increase heart rate. Pacing may also be necessary. The goal is to maintain a higher mean arterial pressure to ensure adequate spinal cord perfusion, given the injury and associated swelling. Lastly, airway protection is crucial, as the shock state and the level of spinal injury can affect respiratory function, potentially necessitating intubation and mechanical ventilation.

10:02

📚 Conclusion and Further Learning

In the concluding paragraph, the presenter thanks the viewers for watching and summarizes the key points covered in the lesson. The unique aspects of neurogenic shock, its clinical signs, and the specific treatment modalities are reiterated. The importance of understanding the differences between neurogenic shock and other types of shock is highlighted. The presenter encourages viewers to like the video and share their thoughts or questions in the comments. Additionally, they promote the next lesson in the series on septic shock and invite viewers to explore other educational content on hemodynamics. The aim is to ensure that viewers have gained valuable knowledge from the lesson and are motivated to continue their learning journey.

Keywords

💡Neurogenic Shock

Neurogenic shock is a type of distributive shock, which occurs due to a central nervous system (CNS) injury, often involving the spinal cord at or above the T6 level. In the video, it is explained as a state resulting from CNS injury that leads to a lack of sympathetic response while parasympathetic activity remains preserved. This condition impacts the cardiovascular system, leading to decreased blood pressure and other symptoms. The script discusses neurogenic shock's effects on coronary vessels, systemic vascular resistance, cardiac contraction, preload, and heart rate.

💡Sympathetic Nerve Outflow

Sympathetic nerve outflow refers to the activation of the sympathetic nervous system, which is part of the body's fight-or-flight response. In the context of neurogenic shock, an injury to the spinal cord can impact this outflow, leading to a lack of sympathetic response. The video script mentions that without this outflow, there is no vasoconstriction, dilation of coronary blood flow, or increase in systemic vascular resistance, which are all critical for maintaining blood pressure.

💡Systemic Vascular Resistance

Systemic vascular resistance (SVR) is a measure of the opposition to blood flow by the systemic circulation. In the video, it is mentioned that neurogenic shock leads to a decrease in SVR, which contributes to a drop in blood pressure. The script explains that the lack of sympathetic activation typically seen in shock states does not occur, resulting in reduced afterload and, consequently, decreased blood pressure.

💡Catecholamines

Catecholamines are hormones and neurotransmitters, such as adrenaline and noradrenaline, produced by the adrenal glands. They play a crucial role in the body's stress response by binding to receptor sites in blood vessels to cause vasoconstriction. The script explains that in neurogenic shock, the release of catecholamines is disrupted, leading to decreased vascular tone and contributing to the shock state.

💡Cardiac Contraction

Cardiac contraction refers to the process by which the heart muscle contracts to pump blood. The video script explains that in neurogenic shock, the lack of sympathetic nerve activation to the heart results in a decrease in the force of cardiac contraction, which contributes to a decrease in cardiac output and preload.

💡Preload

Preload in the context of the cardiovascular system refers to the amount of blood returning to the heart, which stretches the heart muscle and influences the strength of the subsequent contraction. The script mentions that neurogenic shock leads to a decrease in preload due to reduced blood return to the heart, impacting the heart's ability to effectively pump blood.

💡Heart Rate

Heart rate is the number of times the heart beats per minute. The video script indicates that neurogenic shock is characterized by a low heart rate, or bradycardia, due to the lack of sympathetic activation of the SA node of the heart. This decrease in heart rate contributes to the overall decrease in cardiac output.

💡Hypothermia

Hypothermia is a condition where the body temperature drops below the normal range, typically due to an inability to produce or maintain heat. In the video, hypothermia is mentioned as a potential symptom in neurogenic shock patients, resulting from dysregulation within the hypothalamus. Unlike other shock states, patients with neurogenic shock may exhibit warm, dry extremities due to the lack of sympathetic-induced vasoconstriction.

💡Protect the Spine

In the context of neurogenic shock, protecting the spine is a critical aspect of treatment to prevent further damage to the spinal cord. The script emphasizes the importance of maintaining spinal stability through measures such as keeping the patient's bed flat, using a cervical collar, and log rolling the patient to avoid exacerbating the injury.

💡Vasopressors

Vasopressors are medications that constrict blood vessels, thereby increasing blood pressure. The video script discusses the use of vasopressors in the treatment of neurogenic shock when a patient remains hypotensive despite fluid resuscitation. They help to provide the necessary vasoconstriction that the patient's body cannot produce on its own.

💡Inotropes

Inotropes are drugs that affect the force and rate of heart muscle contractions. The script mentions inotropes as part of the treatment for neurogenic shock to compensate for the decreased contractility of the heart due to the lack of sympathetic stimulation. These medications help to improve cardiac output by enhancing the strength of cardiac contractions.

💡Bradycardia

Bradycardia is a medical term for an abnormally slow heart rate. The video script describes bradycardia as a characteristic sign of neurogenic shock, where the patient's heart rate is decreased due to the absence of sympathetic stimulation to the heart. This condition can be addressed with medications or interventions aimed at increasing the heart rate.

💡Mean Arterial Pressure (MAP)

Mean arterial pressure is the average arterial pressure over a complete cycle of the heart. The script highlights the importance of maintaining a higher MAP in patients with neurogenic shock to ensure adequate spinal cord perfusion. This is necessary due to the increased pressure and swelling in the spinal cord caused by the injury.

💡Respiratory Failure

Respiratory failure is a condition where the respiratory system is unable to maintain adequate oxygen levels and remove carbon dioxide. The video script notes that respiratory failure may occur in patients with neurogenic shock, particularly if the spinal cord injury is high enough to affect the respiratory accessory muscles and diaphragm innervation, potentially necessitating intubation and mechanical ventilation.

Highlights

Introduction to the seventh lesson on shock, focusing on neurogenic shock.

Definition of neurogenic shock as a distributive shock resulting from CNS injury.

Explanation of the impact of CNS injury on sympathetic nerve outflow leading to shock.

Absence of sympathetic response in neurogenic shock while parasympathetic response is preserved.

Effects on coronary vessels and systemic vascular resistance due to lack of sympathetic activation.

Decreased blood pressure due to reduced vascular tone in neurogenic shock.

Impact of sympathetic nerve on cardiac function and the resulting decrease in cardiac contraction.

Decreased preload and afterload leading to low cardiac output.

Signs of neurogenic shock include low heart rate and lack of sympathetic innervation of the SA node.

Hypothermia in neurogenic shock due to dysregulation within the hypothalamus.

Importance of ruling out other causes of shock before diagnosing neurogenic shock.

Signs of neurogenic shock include hypotension, bradycardia, and decreased cardiac output.

Treatment of neurogenic shock starts with protecting the spine to prevent further damage.

Use of IV fluids to replace intravascular volume in the treatment of neurogenic shock.

Utilization of vasopressors and inotropes to compensate for lack of sympathetic response.

Medications like dopamine and atropine to increase heart rate in neurogenic shock.

Pacing as a treatment option for hemodynamically significant bradycardia.

Maintaining a higher mean arterial pressure for adequate spinal cord perfusion.

Protecting the airway and potential need for intubation and mechanical ventilation.

Summary of neurogenic shock's unique characteristics and treatment approaches.

Transcripts

you

[Music]

alright and welcome everybody to this

seventh lesson in our series of lessons

on shock in this lesson we're going to

continue our discussion of the various

types of distributive shock specifically

covering neurogenic shock and my name is

Eddie Watson I will be your presenter

for this series of lessons and make sure

and subscribe to our channel below in

order to stay up to date on when our

latest lessons are released and don't

forget to hit the bell icon in order to

get those notifications as those lessons

become available all right so for this

lesson we're gonna take a look at our

neurogenic shock again another type of

shock that is classified as a

distributive shock so like with all the

rest of them we're going to go ahead and

break down our word into its root words

so we have neuro and genic neuro having

to do with the brain and spinal cord and

genic meaning originating from and so in

our case here our shock state is going

to be the result of some sort of CNS

injury and so the CNS injury is going to

be the result of some sort of cervical

or high thoracic and so this is going to

be t6 and above so some sort of injury

to the spinal cord at at least the t6

level or higher and so what happens when

we have a spinal cord injury at this

level or higher is if there is some sort

of impact on the sympathetic nerve

outflow that this is going to have an

impact on things in our body that can

lead to a state of shock

so essentially they'll find themselves

in a state with with no sympathetic

respond but still a preserved

parasympathetic response or activity

and so what does this really mean for

our patients well this is gonna impact

our coronary vessels so again if we

think about that sympathetic response

that fight-or-flight normally we get

that dilation of the coronary blood flow

but in the case of neurogenic shock

we're not going to see that now also

since we're not going to have our

sympathetic activation we're also going

to see a decrease in our systemic

vascular resistance or essentially our

after load and again if you think back

to our first lesson in this series we

have the release of the catecholamines

from the adrenal gland which ultimately

bind with receptor sites in our blood

vessels and work to cause

vasoconstriction

but again in neurogenic shock we're not

going to have this cascade of events

ultimately leading to decreased vascular

tone and since our systemic vascular

resistance plays an important role in

our blood pressure we are going to see

that decreased blood pressure now we

also see this sympathetic nerve

innervate

the heart itself and one of the things

that it does there is it has that

positive inotropic effect and so since

we don't again have that we're going to

see a decrease in our cardiac

contraction now in addition to our

decreased systemic vascular resistance

this means where we're not going to be

getting blood back to the heart as well

as we should so this is going to lead to

a decrease in our preload and finally

one of the most telltale signs of

neurogenic shock is we no longer are

innervating the SA node of the heart and

we're no longer getting that positive

Crona tropic effect of the sympathetic

response and so what happens is you'll

will see a low heart rate in your

patient and so really if we think about

all the factors that go into our cardiac

output we're having an impact on all of

those or decreasing our preload

decreasing our afterload decreasing our

contractility and also decreasing our

heart rate and so this combination of

all of these impacted areas and our lack

of sympathetic response is going to lead

to a low blood pressure

another thing that we also could see in

our patients with neurogenic shock is

hypothermia but one important thing to

note about this is this is going to be

in the patient's core and this is due to

a disc regulation within the

hypothalamus but again if you think

about our lack of sympathetic response

we are not getting that vasoconstriction

that often leads to the cool clammy skin

and so we'll talk about that here in a

minute but our patient will be

exhibiting this this hypothermia within

the body and so one thing that's really

important to note when we're looking at

possibly diagnosing a patient with

neurogenic shock is it's really

important that we rule out all others so

it's really important that we rule out

all other possible causes of shock

before we make the determination that

this is a result of a neurogenic shock

state all right so let's go ahead and

move on to talk about some of the signs

that we would see if we had a patient at

neurogenic shock so as always we're

going to see that decreased blood

pressure or hypotension and this is

going to be a result of that decreased

systemic vascular resistance now one of

the tell-tale signs for neurogenic shock

is that normally our body would attempt

to compensate for this blood pressure by

activating the sympathetic response and

increasing our heart rate and our

vasoconstriction but in this case we no

longer have that ability so you're gonna

find your patient with a decreased heart

rate or bradycardia and along with that

you're often going to see a decreased

cardiac output as well as a decrease in

our CVP or our pulmonary capillary wedge

pressure and again this is a result of

that lack of preload

of the blood not making its way back and

finally like we just talked about you

may also see hypothermia but unlike in

other shock states with this hypothermia

you're actually going to have warm dry

extremities

all right so now let's go ahead and move

on to our treatment and so when we look

at our treatment modalities for a

patient in neurogenic shock probably the

first and most important thing that we

need to make sure we do is we need to

protect the spine and this is very

important because while oftentimes the

damage to the spine may not be

reversible or fixable sometimes it may

be or they may be able to partially

recover some function and so it's

imperative that we do not cause even

more damage and this is where we're

gonna use things like keeping their bed

flat using a c-collar and also log

rolling your patient and so now with

neurogenic shock our first line of

treatment is actually going to be IV

fluids and we're going to look to

replace that intravascular volume and so

essentially we want to be able to

provide more volume of blood in order to

fill all the extra space that now exists

within the vasculature now if the

patient's symptoms persist and they

remain persistently hypotensive then the

next thing we're going to be looking at

doing is using our vasopressors and this

is going to provide the body with that

vasoconstriction that our patient is

just not able to produce themselves but

we might also look at medications like

our inotropes and for these we're

looking to make up for that lack of

contractility again that we're not

receiving as a result of this lack of

sympathetic response now if your patient

remains with a hemodynamically

significant bradycardia then we may also

want to look at ways of increasing our

heart rate so we may try medications

like dopamine which can have a dual

effect on both increasing our heart rate

as well as providing that

vasoconstriction we also often will look

at a medication called atropine and this

medication works to increase our heart

rate by actually blocking the

parasympathetic response which in the

case of neurogenic shock is the

overriding response that our body has

right now and finally may also look at

options such as pacing your patient

and this can be both externally or

internally and so with these

interventions like the fluids and the

pressors and the inotropes and working

to increase their heart rate we're going

to really want to make sure that we're

maintaining a higher mean arterial

pressure than we normally would look in

normal patients and the reason for this

is we're gonna want to be ensuring that

we're providing adequate spinal cord

perfusion and due to the result of the

injury and the swelling that's going on

in the spinal cord we're gonna have to

have a higher map in order to overcome

the increased pressure and increase

swelling in order to profuse that spinal

cord and finally the last thing that we

may need to look at doing for our

patients is we are going to want to be

looking at protecting their airway and

now this may come about as a result of

being in a shock state but also

oftentimes depending on how high the

level of the spinal cord injury that

this could have an impact on respiratory

accessory muscles as well as the direct

innervation of the diaphragm itself

possibly leading to respiratory failure

for your patient requiring intubation

and mechanical ventilation alright so

that just about covers our discussion of

neurogenic shock as you can see the

shock is quite a bit different than some

of the other ones that we've talked to

up to this point and so it really kind

of talked about what's going on and

what's really causing those differences

and how those differences are leading to

that shock state in addition we talked

about some of the signs that you'd see

in your patient and finally covered some

of the courses of treatment that we had

in place specifically for patients with

neurogenic shock and so on that note I

do want to thank you for watching this

lesson I really do hope that you found

this useful for you if you did like the

video and you found it informative

make sure and hit that like button down

below as it really helps to spread the

word about our channel also in the

comments below tell us your favorite

part of this video or feel free to ask

any questions that you might have

finally make sure and check out the next

lesson in this series on septic shock or

also check out another one of our great

series of lessons on hemodynamics thank

you so much for watching and we'll see

you in the next lesson