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