Differentiating Shock

Summary

This video script offers an advanced comparison of different types of shock, focusing on key values like cardiac output, systemic vascular resistance, and mixed venous oxygen saturation. It explains how these values change in cardiogenic, obstructive, hypovolemic, neurogenic, septic, anaphylactic, and dissociated shock, providing insights into the body's compensatory mechanisms and the impact on tissue oxygenation. The script emphasizes the importance of patient history and symptoms for accurate diagnosis.

Takeaways

• 🩺 The script discusses different types of shock and their impact on various physiological parameters.
• 🔍 Cardiac output and systemic vascular resistance (SVR) are key indicators in diagnosing shock, as they relate to blood pressure and tissue oxygenation.
• 📈 In cardiogenic shock, cardiac output is severely decreased, and SVR is elevated to compensate for the drop in blood pressure.
• 🚫 Obstructive shock is similar to cardiogenic shock but involves an obstruction preventing blood flow, leading to increased pulmonary capillary wedge pressure (PCWP).
• 🩸 Hypovolemic shock is characterized by low blood volume, resulting in decreased cardiac output and elevated SVR due to the body's attempt to conserve blood flow.
• 💊 Neurogenic shock involves a reduced sympathetic response, leading to low blood pressure and unique characteristics like bradycardia.
• 🦠 Septic shock is caused by the immune system's response to infection, initially causing vasodilation and a drop in SVR, which can later affect cardiac output.
• 🌡 Anaphylactic shock involves dilation of blood vessels and a large decrease in vascular resistance, with cardiac output increasing to counteract the effects.
• 🔄 Dissociated shock is unique in that both cardiac output and resistance are increased, but tissues are starved of oxygen due to the inability of red blood cells to release oxygen.
• 📊 Mixed venous oxygen saturation (MvO2) is a critical value in assessing shock, as it reflects the oxygen content in the blood after it has passed through the tissues.
• 📝 The script emphasizes the importance of patient history, symptoms, and diagnostic tools in differentiating between the types of shock.

Q & A

What is the primary focus of the video on shock?

The primary focus of the video is to compare different types of shock and to differentiate between them, providing an advanced coverage of the subject.

What are the two key values discussed in the video that are crucial for understanding shock?

The two key values discussed are cardiac output and systemic vascular resistance (SVR), which together determine blood pressure.

How does cardiac output relate to blood flow in the body?

Cardiac output measures the amount of blood the heart pumps out per minute, which directly relates to the blood flow throughout the body.

What does an elevated systemic vascular resistance (SVR) indicate in the context of shock?

An elevated SVR in shock indicates that blood vessels are constricting in an attempt to compensate for a decrease in cardiac output and restore blood pressure.

What is the significance of pulmonary capillary wedge pressure (PCWP) in diagnosing shock?

PCWP, measured with a pulmonary artery catheter, indicates how well the heart is pumping blood forward and can be elevated if the heart is struggling or if there is a blockage.

How does left ventricular end-diastolic volume (LVEDV) relate to the heart's function in shock?

LVEDV represents the volume of blood in the left ventricle just before it contracts. It can be elevated in shock if the heart is overloaded with fluid and not pumping efficiently.

What does a low mixed venous oxygen saturation (MvO2) suggest about the body's oxygenation?

A low MvO2 suggests that tissues have extracted a lot of oxygen, indicating that the body's oxygenation may be compromised.

How does cardiogenic shock differ from obstructive shock in terms of cardiac function?

In cardiogenic shock, the heart's ability to pump is impaired, leading to decreased cardiac output. In obstructive shock, an external factor prevents blood from being pumped forward, but the heart's function itself is not the primary issue.

What is the typical cardiac output and SVR response in hypovolemic shock?

In hypovolemic shock, due to low blood volume, cardiac output is low, and systemic vascular resistance is elevated as the body tries to maintain blood pressure.

How does neurogenic shock affect heart rate and blood pressure?

Neurogenic shock impairs the sympathetic response, leading to low blood pressure and, uniquely, a low heart rate (bradycardia), as opposed to other types of shock where heart rate is increased.

What immune system response is responsible for the vasodilation seen in septic shock?

In septic shock, the immune system responds to infectious material, causing systemic vasodilation and a significant drop in vascular resistance.

How does anaphylactic shock differ from septic shock in terms of vascular response?

Both anaphylactic and septic shock involve vasodilation and lowered vascular resistance, but anaphylactic shock is characterized by an allergic reaction causing widespread swelling, while septic shock is due to an immune response to infection.

What is unique about the cardiac output and resistance in dissociative shock?

In dissociative shock, both cardiac output and resistance are increased, but tissues are not receiving oxygenation due to the inability of oxygen to dissociate from red blood cells.

Why would the mixed venous oxygen saturation (MvO2) be low in dissociative shock?

MvO2 would be low in dissociative shock because tissues are pulling out any available oxygen from the blood, as they are not receiving adequate oxygen from red blood cells.

Outlines

00:00

🩺 Understanding Different Types of Shock

This paragraph introduces the concept of creating a final video to compare various types of shock. The focus is on differentiating between them using key values such as cardiac output, systemic vascular resistance (SVR), pulmonary capillary wedge pressure (PCWP), left ventricular end-diastolic volume (LVEDV), and mixed venous oxygen saturation (MVO2). The video aims to provide a brief overview of these values and their implications in shock conditions, emphasizing the importance of cardiac output and SVR in maintaining blood pressure and tissue oxygenation.

05:03

🚑 Cardiogenic and Obstructive Shock Analysis

The first part of this paragraph discusses cardiogenic shock, which is characterized by a severe decrease in cardiac output due to the heart's impaired pumping ability. As a compensatory mechanism, systemic vascular resistance increases to maintain blood pressure. The heart's dysfunction leads to fluid backup, resulting in elevated PCWP and LVEDV. Mixed venous oxygen content is lower due to reduced blood flow allowing tissues to extract more oxygen. The second part quickly addresses obstructive shock, which is similar to cardiogenic shock but caused by an obstruction preventing blood from being pumped forward, leading to increased PCWP and decreased MVO2. Differentiating these two types of shock requires understanding the patient's history and symptoms.

🌡 Hypovolemic, Neurogenic, and Septic Shock Overview

This paragraph delves into hypovolemic shock, where low blood volume results in decreased cardiac output and oxygen delivery. Systemic vascular resistance is elevated as the body tries to compensate for the low blood volume. In neurogenic shock, there's an impaired sympathetic response leading to low blood pressure and bradycardia, with no change in ventricular volume and decreased MVO2 due to slowed blood flow allowing more time for oxygen extraction. Septic shock is caused by the immune system's response to infection, initially causing vasodilation and decreased vascular resistance, with cardiac output potentially increasing or decreasing in later stages. Fluid load and oxygen extraction can vary, with tissues potentially not extracting oxygen properly due to swelling and fluid accumulation outside blood vessels.

🌪 Anaphylactic and Dissociative Shock Characteristics

Anaphylactic shock is characterized by increased swelling, which hinders proper oxygen distribution to tissues, and a large decrease in vascular resistance due to blood vessel dilation, similar to septic shock. Cardiac output is elevated to counteract the decreased resistance, with pulmonary capillary wedge pressure remaining unchanged or slightly decreased. Dissociative shock is unique, with both cardiac output and resistance increased, but tissues not receiving oxygen due to the inability of oxygen to dissociate from red blood cells. Despite these compensatory mechanisms, tissue starvation occurs, and MVO2 is lowered as tissues extract what oxygen they can. Free-floating oxygen in the plasma is also low due to the tissues' oxygen deprivation.

Keywords

💡Shock

Shock is a life-threatening medical condition characterized by inadequate blood flow to organs and tissues, leading to cellular dysfunction and organ failure. In the video, shock is the central theme, with various types being discussed to differentiate their causes and effects on the body.

💡Cardiac Output

Cardiac output refers to the volume of blood pumped by the heart per minute, measured in liters or milliliters. It is a critical parameter in assessing circulatory function. In the script, decreased cardiac output is associated with cardiogenic shock, indicating the heart's impaired ability to pump blood effectively.

💡Systemic Vascular Resistance (SVR)

Systemic vascular resistance is the measure of resistance to blood flow in the systemic circulation. It is an important factor in maintaining blood pressure. The video explains how an increase in SVR can compensate for a decrease in cardiac output in certain types of shock.

💡Pulmonary Capillary Wedge Pressure (PCWP)

Pulmonary capillary wedge pressure is a measure of pressure in the pulmonary artery, obtained using a pulmonary artery catheter. It reflects the heart's ability to pump blood forward. In the script, elevated PCWP is indicative of fluid backup in the heart, as seen in cardiogenic and obstructive shock.

💡Left Ventricular End-Diastolic Volume (LVEDV)

Left ventricular end-diastolic volume is the amount of blood in the left ventricle just before it contracts. It is a measure of the heart's preload. The video mentions increased LVEDV in conditions where the heart is overloaded with blood, such as in cardiogenic shock.

💡Mixed Venous Oxygen Saturation (MvO2)

Mixed venous oxygen saturation is a measure of the oxygen content in the blood returning to the heart, reflecting the balance between oxygen supply and demand in the body. The script explains that a low MvO2 indicates tissues have extracted a lot of oxygen, which can be seen in various types of shock.

💡Cardiogenic Shock

Cardiogenic shock is a type of shock resulting from the heart's inability to pump blood effectively. The script describes it as having severely decreased cardiac output, elevated SVR, and increased PCWP and LVEDV, all pointing to heart dysfunction.

💡Obstructive Shock

Obstructive shock occurs when an obstruction prevents blood from being pumped forward by the heart. The script compares it to cardiogenic shock, noting similar effects on PCWP and MvO2, but with the cause being an external blockage rather than heart impairment.

💡Hypovolemic Shock

Hypovolemic shock is caused by a significant loss of blood or fluid in the body, leading to low blood volume and reduced cardiac output. The video script explains that in this type of shock, SVR is elevated due to the body's attempt to maintain blood pressure despite low blood volume.

💡Neurogenic Shock

Neurogenic shock is caused by a loss of sympathetic tone to the heart and blood vessels, resulting in low blood pressure. The script highlights that it is unique in that it can cause bradycardia, a slow heart rate, unlike other types of shock where heart rate is typically increased.

💡Septic Shock

Septic shock is a severe form of shock resulting from sepsis, an overwhelming immune response to infection. The script describes it as initially causing vasodilation and a drop in SVR, with cardiac output potentially increasing or decreasing depending on the stage of the condition.

💡Anaphylactic Shock

Anaphylactic shock is a severe allergic reaction that can cause a rapid drop in blood pressure. The script explains that it involves vasodilation, similar to septic shock, leading to decreased vascular resistance, and an initial increase in cardiac output to compensate.

💡Dissociative Shock

Dissociative shock is a condition where oxygen cannot dissociate from red blood cells, leading to tissue hypoxia despite normal or increased blood flow. The script notes that both cardiac output and resistance are increased in an attempt to improve oxygen delivery, but the tissues still experience oxygen starvation.

Highlights

Introduction to creating a final video on shock, aiming to compare different types and differentiate them.

Explanation of cardiac output as a measure of blood pumped by the heart per minute.

Definition of systemic vascular resistance (SVR) and its role in blood pressure regulation.

Importance of cardiac output and SVR in tissue oxygenation.

Introduction of pulmonary capillary wedge pressure (PCWP) as an indicator of heart's pumping efficiency.

Description of left ventricular end-diastolic volume (LVEDV) and its relation to heart overload.

Role of mixed venous oxygen saturation (MvO2) in reflecting tissue oxygen extraction.

Cardiogenic shock characterized by decreased cardiac output and increased SVR.

Elevated PCWP and LVEDV in cardiogenic shock due to fluid backup.

Lowered MvO2 in cardiogenic shock indicating intense tissue oxygen extraction.

Differentiation between cardiogenic and obstructive shock based on patient history and symptoms.

Hypovolemic shock marked by low blood volume and decreased cardiac output.

Neurogenic shock characterized by impaired sympathetic response leading to low blood pressure.

Unique feature of neurogenic shock: bradycardia in contrast to other shock types.

Septic shock involves immune system response causing vasodilation and varying cardiac output.

Anaphylactic shock with increased swelling and lowered vascular resistance similar to septic shock.

Dissociated shock characterized by increased cardiac output and resistance without proper oxygen dissociation.

Encouragement for viewers to review and understand the differences among shock types.

Transcripts

so I want to create one final video on

shock and this is the video to really

compare all the different types of shock

and see how you can differentiate

between them now this will be an

advanced coverage of all the different

types of shock so most of my detail will

be very brief and give you a general

gist of the type of shock but of all of

these I want to look at four different

values the first is cardiac output and

of course cardiac output is how much

fluid how much blood the heart puts out

per minute so it's usually measured in

liters per minute or milliliters per

minute SVR stands for systemic vascular

resistance

so that's resistance of all the blood

vessels in the body and the two of these

cardiac output and systemic vascular

resistance equal blood pressure so

usually in shock when one value goes

down the other will go up to try to

compensate unless both of them are shut

down cardiac output and systemic

vascular resistance also provide

information on tissue oxygenation if

they're decreased tissue oxygenation can

be decreased as well bcw P stands for

pulmonary capillary wedge pressure and

this is measured with a pulmonary artery

catheter it tells you how well the heart

is able to pump fluid forward if the

heart is struggling or if there's some

blockage or something preventing blood

from being pushed forward by the heart

then P C WP pulmonary capillary wedge

pressure will be elevated and lved V

stands for left ventricular

end-diastolic volume it's the volume of

blood in the left ventricle at the end

of relaxation basically it's how much

blood is in the left ventricle just

before it squeezes out so this will also

be elevated in a heart that is

overloaded with fluid and last of all

the value M vo2 which stands for mixed

venous oxygen saturation this will

usually be low when the tissues have

extracted a lot of oxygen this is

measured in the right atrium so it's a

way to average out the oxygen content in

the blood and

of tissues in the capillaries are able

to extract oxygen the total amount of

oxygen going back to the heart will be

decreased so that would be a decreased

mixed venous oxygen content and

vice-versa

if the tissues are unable to extract

oxygen oxygen will be left in the

bloodstream and this value will be

elevated okay so that's the basics let's

go ahead and get started on this

so cardiogenic shock is an issue with

the heart's ability to pump so right

away we know that cardiac output is

going to be decreased pretty severely

depending on how severely the heart

muscle is impaired with a decreased

cardiac output the blood vessels are

going to clamp down and so you'll have

an elevated systemic vascular resistance

in an attempt to return blood back to

the heart and restore blood pressure the

heart's inability to function leads to

backup of fluid and usually this

accumulates in the heart

so you'll see an elevated pulmonary

capillary wedge pressure as well as the

left ventricular end-diastolic volume so

these will be increased because blood is

not squeezed out of the heart properly

last of all mixed venous oxygen content

will be lower and that's because since

blood is not flowing as quickly because

the heart is shut down any oxygen that

remains in the blood is pulled furiously

out by the tissues and so you'll see a

lower content of oxygen when Blood

returns to the heart

now obstructive all I'll rush through

really quickly because it's pretty much

identical to cardiogenic shock instead

of the heart being affected it's

something outside of the heart that's

preventing fluid from being squeezed

forward so of course blood is left in

the heart meaning a piece ewp will be

elevated and going back over here fluid

can't be pushed out of the heart because

of some sort of obstruction whether this

is a pulmonary embolism preventing blood

from getting from the right side of the

heart to the left side of the heart or

if it's cardiac tamponade or aortic

stenosis or or any of that and the blood

vessels will compensate by trying to

increase vascular resistance

and last of all tissues are trying to

pull out oxygen furiously

so it's will see a lo MV o2 to really

differentiate these two it's important

to know a patient's history as well as

the symptoms that they're experiencing

and the onset of the symptoms as well

for example if a patient has history of

heart attacks it may be more likely that

cardiogenic shock is the cause so you'll

go through your different diagnostic

tools to determine whether it's

cardiogenic or obstructive shock

now hypovolemic shock the issue is low

blood volume so because of low blood

volume there is a low amount of blood

that can be squeezed forward from the

heart low fluid return to the heart

means low cardiac output low delivery of

oxygen and because of this low blood

volume blood vessels are trying to clamp

down and so systemic vascular resistance

will be very elevated the fluid

accumulation in the heart that's left

over will actually be very low because

right it's hypovolemic low volume in the

body and tissues we'll be extracting

oxygen furiously leaving the MV o2 to be

much lower

next neurogenic shock causes impaired

sympathetic response to the heart and

the blood vessels so you have very low

blood pressure because both the heart

and the blood vessels are getting low

sympathetic tone and if no in neurogenic

shock you have bradycardia low heart

rate this is very unique to neurogenic

shock as in all the other shocks heart

rate is increased to try to compensate

for the low blood pressure and there

should really be no change in

ventricular volume and there will be a

decrease in mixed venous oxygen

essentially the circulatory system

collapses so blood flow slows way down

and so oxygen is exposed to the tissues

longer as blood traverses through the

blood vessels giving more time for

oxygen extraction next we have septic

shock now the cause for shock in sepsis

is the immune system the immune system

responds to infective material and

causes systemic

their dilation vasodilation so vascular

resistance drops tremendously to

compensate for this the heart initially

tries to pump faster but as time goes on

as a patient is exposed to sepsis for a

longer period of time the immune

molecules can paralyze the heart and

cause damage which will lead to

decreased cardiac output so cardiac

output can either be elevated initially

or lower in later stages of septic shock

the fluid load on the heart is really

not affected maybe a little bit lowered

and oxygen extraction can either be

elevated or decreased and the reason you

might have an elevated MV o2 mixed

venous oxygen saturation is because the

tissues aren't extracting it properly

septic shock causes a lot of swelling

throughout the body and this can make it

difficult for oxygen to be delivered to

the tissues a lot of fluid is

accumulating just outside of the blood

vessels and so oxygen has to travel a

longer way to get from the blood vessels

to the tissues that need the oxygen and

so that's a perfect segue into

anaphylactic shock there's also

increased swelling and that's one of the

major symptoms of anaphylactic shock

so oxygen cannot be distributed to the

tissues properly and also an

anaphylactic shock you have a large

lowering of vascular resistance the

blood vessels throughout the body dilate

which is very similar to septic shock

now cardiac output will be elevated in

an attempt to counteract the decreased

resistance and the pulmonary capillary

wedge pressure will be the same maybe a

little bit decreased now last of all we

have dissociated shock and this is a

very interesting shock because both

cardiac output and resistance are going

to be increased the tissues are not

getting oxygenation because oxygen

cannot dissociate off of red blood cells

so because of that the body attempts to

increase the heart rate and improve

cardiac output as well as clamp blood

school's down to distribute oxygen

properly however regardless of these

changes red blood cells cannot

dissociate from their oxygen and so that

is causing tissue starvation so looking

over at mvo to the tissues will pull out

any oxygen they can from the blood so MV

o2 will be lowered free-floating oxygen

in the plasma in the blood plasma will

especially be low since tissues are not

getting their oxygen from the red blood

cells and finally the pulmonary

capillary wedge pressure or the fluid

overload of the heart will be about the

same no real change so I encourage you

to go back and look over this chart and

attempt to do it on your own to really

reason through each of these types of

shock to understand how they cause

decreased oxygen perfusion