so here I have outlined the just a
general concept of the cardiovascular
system we have the heart over here the
arteries deliver blood to the organs and
the veins deliver blood back from the
organs to the heart so the reason I'm
going to draw this is because the
cardiovascular system is critically
affected in neurogenic shock now what is
neurogenic shock neurogenic shock occurs
when the nervous system is no longer
functioning properly and this can happen
from a number of things sometimes and
actually most frequently it's from
trauma so if a patient has something
occur to their spinal cord where it's
severed or an epidural goes wrong and
some nerves are damaged that can lead to
neurogenic shock if it's severe enough
now what neurogenic shock essentially is
is loss of vascular tone and pooling of
peripheral blood so the nervous system
provides tone to the blood vessels and
also to the heart and this tone is is
known as sympathetic tone it's kind of
like muscles you know if you think about
somebody who's flexing versus not
flexing of course there's a certain
tightness that the muscles undergo when
you flex now that's really happening to
the blood vessels at all times and it's
done to really maintain blood pressure
blood vessels are somewhat tightened in
and squeeze down a little bit to allow
blood to flow through the idea is as
blood flows through the vascular system
it's going to be maintained in a four
direction by the blood vessels because
if it hits up against the wall the blood
vessel bounces it back and pushes the
blood forward if it didn't do this if
there was no vascular tone blood would
run up against the wall and lose a lot
of its energy would be really dampened
so it's kind of like a trampoline you
know when you're bouncing on a
trampoline
if the trampoline is taut enough you'll
be able to bounce up and down really
easily right however if you if you think
about loosening the trampoline if you
loosen the material on the trampoline
you won't be able to bounce as high and
so that's the same thing that happens
here when you loosen the blood vessel it
won't be able to bounce blood forward as
well so like I said the nervous system
provides this tone this vascular tone to
both the arteries and the veins so now
what happens if we shut down this
nervous system well the blood vessels
will lose their tightness both the
arteries and the veins so I'm going to
go ahead and erase this to show that the
blood vessels kind of become floppy and
I'm going to really exaggerate this by
making them really wide so both the
arteries and the veins become very
floppy so you can see if this happens in
the arteries Bloods not really going to
make it to the organs as well right it's
supposed to bounce off and bounce
forward but that's not really happening
anymore so it just kind of slowly makes
it to the organs so you have shock you
have decreased oxygen delivery decreased
tissue perfusion to the organs and then
blood of course trying to flow back to
the heart won't be able to it'll just
kind of pool it'll just stay in the
venous system and only a minimum amount
will return to the heart so this will
actually affect the cardiac output of
the heart remember blood pressure and
tissue perfusion are related to cardiac
output and vascular resistance systemic
vascular resistance so up here in the
arteries we've already shown that this
systemic vascular resistance is
decreased so that's going to lead to a
decrease in blood pressure and tissue
perfusion so let me let me actually go
and write that out blood pressure and OH
- delivery tissue perfusion is oxygen
delivery so both of these will go down
because resistance in the arteries are
going down and now also the veins aren't
able to deliver blood back to the heart
and if we recall you can recall cardiac
output is stroke volume times heart rate
so if we decrease the amount of blood
going back to the heart that means
there's going to be less blood that the
heart can squeeze forward so that means
less
drop volume right decreased delivery of
blood to the heart leads to decreased
stroke volume which means decreased
cardiac output and that further worsens
blood pressure and further worsens
oxygen delivery you're shutting down the
cardiovascular system by not being able
to maintain vascular tone something else
that you see it in neurogenic shock is
you know the nervous system the
sympathetic nervous system controls the
heart rate now if you no longer have the
input of the nervous system the heart
rate is going to drop and so we go back
to our equation heart rate drops cardiac
output drops even further and blood
pressure will drop and then oxygen
delivery will also drop so this is truly
shock tissue perfusion is just
completely demolished and so is blood
pressure so the entire cardiovascular
system is just not able to maintain
blood flow and that leads to a shutdown
of oxygen delivery and so let me go
ahead and scroll down so we can think
about some of the symptoms I'm going to
keep this somewhat in view so you can
still ponder it and think about it but
the symptoms of neurogenic shock will be
those of decreased oxygen delivery such
as altered Mental Status
you know decreased urine output you
think about anything that needs oxygen
any organ that needs oxygen and think
about what would happen if it wasn't
getting oxygen it would start to shut
down so organ dysfunction can occur
organ dysfunction and a major symptom
that you see specific to neurogenic
shock is bradycardia now this is
something that you should really be
thinking about this is really the only
shock that has bradycardia remember all
the other shocks are going to try to
increase heart rate speed it up to try
to deliver oxygen and deliver blood to
the body but here we have the heart rate
dropping because it's no longer getting
input from the nervous system and so we
have a low heart rate bradycardia so
this is a key symptom of neurogenic
shock another main symptom that I want
to touch on is
warm skin warm skin occurs because of
the dilation of all blood vessels so
these blood vessels in the skin will
dilate well you know they will enlarge
like we were showing up here so blood
can flow through the skin more easily
and that's a problem because it diverts
blood away from vital organs such as the
brain the lungs in the heart and so the
treatment of neurogenic shock will focus
on trying to maintain this blood
pressure so you'll give medication known
as pressors
pressors allow the blood vessels to
clamp back down if you clamp the vessels
down it directly is affecting the issue
in neurogenic shock and you'll also give
a lot of IV fluids to try to maintain
the fluid volume right if you increase
the amount of fluid in the vasculature
it's more likely that you'll be able to
push it forward and deliver blood to the
system so IV fluid and pressors help
maintain the blood pressure and a final
medication that you'll see is atropine
atropine works by blocking the
parasympathetic nervous system so it's
like stopping the rest and relaxation
part of the nervous system and increases
the fight-or-flight so increasing the
fight-or-flight response will increase
the heart rate so giving atropine will
help raise up the heart rate to increase
cardiac output and to improve the
pumping of blood throughout the
cardiovascular system