By Adem Lewis / in , , , , , , , , , /

Welcome to another MedCram
lecture we’re going to talk today about shock there’s different types of shock we’re
going to talk about all three one is called hypovolemic shock then you’ve got
cardiogenic shock and you’ve got septic shock we’re going to go through these
three different types of shock how they’re different and why you need to
know them what I want to do is kind of diagram out what it is I’m talking about
okay so the first thing I want to do is draw some compartments because that’s
going to be very important the first thing I want to draw is the vascular
compartment and this is where basically the blood is stored okay then it goes
into the vasculature which is then goes into the heart once you understand these
things I think it’s going to be a lot easier to understand and then there’s a
decision that’s made a choice where it can either go to the vital organs or the
non vital organs okay so we got vital organs here and then we’ve got the non vital organs
what is a non vital organ well something like skin would fit into that category
it’s kind of vital but not absolutely essential the body’s got to make a
decision at some point about where blood is going to go if there’s not enough of
it to go around and then of course everything goes right back to where it’s
being held okay so we’ve got the vasculature and this is sort of the
storehouse of blood it’s primarily in the venous system and so this is where
you can have problems and so we’ll call this a okay next is B which is the heart
and then finally last is C which is the vasculature and so these are the three
areas that really contribute to shock so let’s figure out what’s happening in the
normal system so you’ve got blood blood goes to the heart the heart then pumps
blood to the non-vital and the vital organs and why does this happen
this happens because you need oxygen oxygen needs to get to these organs
otherwise these organs will go into shock so what is shock shock is a
situation where the vital organs are not getting oxygen if vital organs don’t get
oxygen your body will go into shock because these organs will shut down and
if they shut down more than three of these organs shut down there’s a very
high mortality associated with this and so not only are we going to talk about
the different types of shock but we’re going to talk about the different ways
of fixing shock in these specific organ systems but it’s important for you to
get a kind of a sense about what’s going on you’ve
got blood blood goes to the heart the heart then pumps that blood and
important because that blood the hemoglobin molecule specifically is
binding to oxygen and taking an oxygen molecule to the target tissues now why
did those target tissues need oxygen you may recall from biochemistry that oxygen
is needed as the final electron acceptor so that the electron transport chain can
continue to function and FADH2 NADH gets transported across and you get protons
pumped into the intermembrane space which then come back into the matrix of
the mitochondria to make ATP if you don’t make ATP you’re dead
okay basically so your target tissues need oxygen
so there are three places where that can break down a if you don’t have enough
blood that can cause a problem and you’ll eventually get into shock because
there’s not enough oxygen reaching the organs B if your heart is just not
strong enough to pump that blood to your organs and finally see kind of a septic
shock or distributive shock if there’s a problem here in the way the body
regulates how much blood goes to the vital and non vital organs so in other
words if it starts messing up and things start going this way and less going this
way that can be a problem and that can cause less oxygen to go to your vital
organs so three different possibilities okay now I want to break this down so
you can see the differences first of all I’m going to make a column here and
we’re going to have three different columns and we’re going to have eight different
rows and we’ll see if we can get all of this
in here so you can understand okay so there are three different types of shock
the first type of shock is what we call hypovolemic shock I’m going to make that
red because that has to do with blood hypovolemic
you can follow along hair on your piece of paper now hypovolemic has to do with
letter A that’s where there’s a problem at a there’s not enough blood it’s just
not enough blood and so let’s go ahead before we go through all of these and
quickly label what I want to talk about here we’re going to talk about some
issues Co is the cardiac output HR is the heart rate SVR is systemic vascular
resistance it’s kind of the resistance right here s the R what is the
resistance to flow in these blood vessels that’s what SVR basically is EF
is the ejection fraction it’s how much blood does the heart pump out it’s a
surrogate for basically how strong is the heart beating then we have something
called the post capillary wedge pressure this is this is measured by something
called the right heart catheter it’s where you float a balloon into the
pulmonary artery and there’s a little tip distal to that balloon that can
measure what the pressure is in the pulmonary artery when there’s no more
pulsation coming from the right ventricle this is a surrogate for the
pressure in the pulmonary capillary which is a surrogate for the pressure in
the pulmonary vein which is a surrogate for basically the pressure in the left
atrium so when you see pulmonary capillary
wedge pressure I really want you to think left atrium because that’s really
what it’s measuring next one is jvp that’s the jugular venous pulse when you
see that I want you to think right atrium then we’ve got blood pressure and
then finally skin the temperature okay let’s go
through these then and I think this will be very instructive to figure out what
happens in hypovolemic shock so in hypovolemic shock you’ve got a lot of
bleeding you’ve bled out from an accident from a GI bleed something’s
going on and so what’s the first thing that you’re going to see well the first
thing you’ll see is your jugular venous pressure is low and that makes sense
jugular venous pressure is measured right here if you don’t have a lot of
blood obviously the pressure is going to be low if your pressure going into your
heart is low just from the starlings forces if your preload is low your
cardiac output is going to be low as a result your heart’s going to try to
compensate so your heart rate is going to go up then what’s going to happen
because it’ll compensate at some point it’s not going to compensate anymore
it’s going to go and get worse and worse and your blood pressure is going to
start to go down as a result of that your ejection fraction may go up to
compensate but as the blood pressure goes down your systemic vascular
resistance is going to go up now this is important if the cardiac output slow
right here okay the and your blood pressure is low then these arteries are
going to try to squeeze together to bring the blood pressure up so there’s
enough pressure to reach the non-vital and the vital organs that’s why the SVR
or the systemic vascular resistance goes up now you can imagine if there’s not
enough volume circulating both your right atrial pressure and your left
atrial pressure are going to be low now here’s the important thing because the
pressure is low and systemic vascular resistance is increasing which one do
you think is going to increase more this is going to increase more the blood
going to the vital organs or more going to the non vital well you’re right it’s
going to actually shunt a lot of the blood towards the vital organs and it’s
going to close off the non-vital like the skin and so
therefore your skin temperature is going to be cool it’s going to be low so
that’s what happens in hypovolemic shock okay let’s talk about cardiogenic shock
will make that green cardiogenic shock that’s B that’s where we are here at B
okay so what’s the primary problem with cardiogenic shock primary problem is the
heart is not working and your cardiac output is going to be low so that’s
where it’s starting notice we’re starting in a different place here the
problem is not not enough volume the problem is there’s not enough cardiac
output as a result of that the heart rate may speed up unless of course the
thing that’s causing your cardiogenic shock is something like beta blockers
and therefore your heart rate would be good low so just depends on what’s
causing your cardiogenic shock and that’s going to be the thing that causes
it to have problems so when that happens what do you think is going to happen to
the pressure of fluid behind the heart well if the heart’s not pumping
everything’s going to back up and so both your left atrial pressure and your
right atrial pressure are both going to go up because you’re in cardiogenic
shock however your blood pressure is going to go down now what do you think
is going to happen to your systemic vascular resistance well again because
your heart is having a problem pumping blood your blood vessels are going to do
the same thing your blood vessels don’t know the difference between whether it’s
the heart not pumping or just not having enough blood they’re going to do the
same thing and so systemic vascular resistance is going to go up your
ejection fraction obviously because you’re in cardiogenic shock is good to
be low and what’s going to be your skin temperature once again since you’re
having constriction here and you’re getting a shunting of blood from the non
vital to the vital organs your skin temperature is going to be cold okay so
let’s take a moment to notice what the difference is between hypovolemic and
cardiogenic shock everything else is the same really except for the fact that
these indices go up versus go down so if you can measure the jvp that would be a
great way of determining if someone is in hypovolemic or cardiogenic shock okay
let’s talk about septic shock now septic shock is a lot different
septic shock is caused by an infection and when you have an infection you’ve
got an immune response against that well something funny happens when you
get that immune response that immune response or these antibodies or cells
will have them down here as cells they release cytokines and chemokines and all
of these sorts of things and what do they do they cause dysregulation of
vasoconstriction here that where we’ve been talking about at the arterioles
both going to the non vital and vital organs and basically what happens is
because there’s dysregulation and specifically vasodilation
okay so opening up widening there is this shunting of blood if you will to
non vital organs away from the vital organs so where’s the problem the
problem starts off here at the systemic vascular resistance systemic vascular
resistance plummets it drops and that’s a big problem and as a result of that
you have compensation so in other words if this thing opens up and the pressure
just drops which you’ll see blood pressure drops and septic shock that
causes a compensatory increase in heart rate and an increase in cardiac output
at least early on in septic shock the ejection fraction because of the
infection actually is stunned and drops somewhat okay and as a result of the
increased cardiac output the post capillary wedge pressure actually drops
and so does your jugular venous pulse it also drops now because there’s this
regulation here and blood is going to the skin believe it or not your skin
temperature is actually up and if these patients
actually feel very warm so notice here that whereas in cardiogenic shock your
post capillary wedge pressure and jugular venous pulse was high in septic
shock it’s low so what I would recommend is studying these looking them over and
over so you can see quickly the differences skin temperature is very
important sometimes you can just walk into a room and touch the patient and
look up on the monitor and see that they’ve got a fast heart rate and see
that their blood pressure is low and just by simply touching the skin and
a feeling if it’s very warm you can tell if this patients in septic shock
although it’s not a hundred percent of course and there’s other things that you
should look at but the key here is is that there are certain readings that
you’ll see depending on the type of shock that you’re in and knowing where
everything starts off you’ll be able to fill in the rest of the blanks so
there’s another lecture coming up talking about how we treat septic shock
and using something called early goal-directed therapy and that’s very important it’s been shown to save lives
we’ll talk about why it’s important to to use early goal-directed therapy all right thanks for joining me

Leave a Reply

Your email address will not be published. Required fields are marked *