Alright, now when we think
about hemorrhagic shock,
one of the questions we
always have to ask ourselves
is where is the blood?
You need to identify where
the blood is in the body
and where it’s gone, so that you
can plan your treatment accordingly.
So blood is not gonna be in the head
if your patient is in hemorrhagic shock
except maybe in infants, right?
The head in adults is not large enough to
hold enough blood volume to cause shock.
Now, infants have relatively larger
heads compared to their body sizes
and their heads are distensible.
So there actually are
cases where infants with
hemorrhages can be in shock.
we’re not gonna think about the head.
What we are gonna think
about is the thorax.
Each hemithorax can hold a liter
to a liter and a half of blood,
so that’s definitely
enough to put you
at least in the early
stages of shock.
Blood’s not gonna be
in the extremities.
They typically do not hold
enough blood volume for that.
You can maybe lose a unit of blood
into each thigh from a femur fracture.
But again, that’s not really gonna
be enough to cause significant shock.
The abdomen however, definitely can
hold enough blood volume for that.
The abdomen is large,
it’s readily distensible,
it’s very easy to put
a lot of blood into it.
So interabdominal injuries are
commonly associated with shock.
As our pelvic injuries
for the same reason.
But the neck, definitely not an area
where you’re gonna be able to get
hemorrhagic shock unless you’re
and that’s the caveat
with all of these.
The other places the blood can be in every
case is on the floor, at the scene, etc.
So remember, patients bleed internally
but they obviously also bleed externally.
So you always wanna get a
sense from your paramedics
about how much blood was at the scene,
how much blood was lost in the ambulance,
and you wanna get a feel
for how much ongoing
external blood loss
there isin the ED
to see if that could potentially
account for the hemorrhagic shock
that you’re seeing
in your patient.
You have identify where
the blood has gone
because this is gonna dictate
how you manage the patient.
A patient with intraabdominal
hemorrhage needs operative management.
A patient with thoracic
hemorrhage needs chest tubes, etc.
So you need to understand
where the blood is
so that you can treat the
So that pretty much
covers hemorrhagic shock.
The other type of shock to be aware
of in trauma is obstructive shock
which is caused by injuries like cardiac
tamponade and tension pneumothorax.
occurs when there is
an extra cardiac obstruction
to normal blood flow.
In the case of both of
these disease processes,
there’s actually mechanical
compression of the heart.
In the case of pneumothorax
by an air collection.
In the case of cardiac tamponade
by a pericardial fluid
collection or blood collection.
In both cases, the compression of the
heart mechanically impedes venous filling.
And of course, if the heart doesn’t
fill normally during diastole,
it can’t pump blood out to the body
normally which is gonna lead to shock.
We’ve addressed tension
pneumothorax in another lecture
and we’re gonna talk about
cardiac tamponade at the end.
So what diagnostic test can identify
all the potential etiologies
for shock in trauma patients?
Wouldn’t it be great if there
was just one thing we could do
to really get to the bottom of
why our patient is in shock?
Well, it turns out that there
is and that’s the E-FAST
which is the extended focused
abdominal sonography in trauma exam.
And it’s basically a bedside ultrasound
exam that’s designed to localize
where the blood is if the
patient is in hemorrhagic shock.
It’s designed to identify
hemopericardium and pneumothorax,
so that we can address our
causes of obstructive shock.
It could be performed right there at the
bedside as part of the secondary survey,
and it was originally developed for
use in unstable blunt trauma patients.
But it actually can be used in any trauma
patient as an adjunct to your physical exam
to give you a better sense of
what’s going on with the patient.
So there are five views that we
do as part of the E-FAST exam.
There’s the right upper quadrant,
the left upper quadrant, the bladder view,
the pericardial view,
and the bilateral lung views.
The bottom line on E-FAST is that
you’re answering three yes/no questions
and those questions are,
is there hemorperitoneum?
Is there hemopericardium?
And is there pneumothorax?
What you’re not answering with E-FAST
is, what is the injured organ?
How much blood is in there?
How badly is it injured?
Is it going to be treatable conservatively
or is it going to need surgery?
You’re not answering
You are simply answering questions about
whether there is unauthorized blood
or air in major body cavities and
that’s really important to remember.
So when we think about
a few basic principles will
help us interpret our images.
Fluid on ultrasound is anechoic, it’s
always gonna appear as black on your image.
So when you look at blood vessels,
when you look at the chambers of the heart,
they’re all gonna be
filled with black.
Air on the other
hand is hyperechoic.
Air appears as white on ultrasound and
then tissue based on its consistency
and composition is gonna be
varying shades of grey in between.
The goal of the E-FAST again is
to detect blood or air in places
where they don’t belong.
So our goal as we perform
this exam is gonna be to look
for black or white in places
where we don’t want to see it.