okay well welcome to another MedCram lecture we could talk today about shock
there's different types of shock we're gonna talk about all three one is called
hypovolemic shock then you've got cardiogenic shock and you've got septic
shock we're gonna go through these three different types of shock how they're
different and why you need to know them well 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 gonna 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 gonna 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 central to body's got to make a decision at some
point about where blood is gonna 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
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 do 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 gonna make a column here and we're going to have three
different columns and we're gonna 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 gonna make that red cuz that has to do with blood
hypo Foley Mick 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
but 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 and 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 gonna see well the first
thing you'll see is yet your jugular venous pressure is low and that makes
sense jugular venous pressure is measured
right here 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 gonna try to compensate so your heart rate is gonna
go up then what's gonna happen because it'll compensate at some point it's not
going to compensate anymore it's gonna get worse and worse and your blood
pressure is gonna 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 slowed 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 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 gonna actually shunt a lot of the blood
towards the vital organs and it's gonna close off the non vital like the skin
and so therefore your skin temperature is gonna be cool
it's gonna be low so that's what happens in hypovolemic shock okay let's talk
about cardiogenic shock will make that green cardio genic 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 it's the harshest not working and your cardiac
output is gonna 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 gonna be the thing that
causes it to have problems so when that happens what do you think is gonna
happen to the pressure of fluid behind the heart well if the heart's not
pumping everything's gonna 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 gonna 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 vs. 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
pick shocked 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 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