Let’s take a look at important differential
diagnosis for you in ARDS. Pulmonary edema.
ARDS should have a low pulmonary capillary wedge pressure.
Can be challenging. Both sepsis with ARDS
and low output congestive heart failure will
have hypotension and bilateral pulmonary infiltrate.
What does that mean? It means that if you
had sepsis by itself. Listen, it's a neurogenic
or septic type of shock, right? So this would
then mean that your blood vessels are severely
vasodilated or vasoconstricted? Vasodilated
severely. That gram negative organism, lipopolysaccharide
causing massive vasodilation. If
you have massive vasodilation universally,
arterial side, through the capillaries, through
the veins, you are not able to properly supply
oxygen to your tissue. Hence, shock. We had
this discussion during our shock type of lecture.
But, anyhow. So, now, you have sepsis by itself
then you would have increased cardiac output
because of decreased afterload. But,
then if you have sepsis causing ARDS, which is
quite common, then you are going to have low
output. And you have hypertension. Low output
congestive heart failure will have hypertension,
both of these will. Next, ARDS. Both areas
of the lungs, the alveolar has collapsed,
therefore, you will have bilateral pulmonary
infiltrate. If you have congestive heart failure,
what are you going to find? Pulmonary edema.
Back up. That is cardiogenic, transudates,
but obviously, this is bilateral type of
Next, pneumonia a differential. The grey
area as pneumonia can be caused of ARDS, be
careful. And then neonate. Respiratory distress
of a newborn but this would be due to surfactant
deficiency as we shall see. Some important
differentials here. Be able to go
through the first two bullet points. Pulmonary
edema, but ARDS will have a lower to normal
pulmonary capillary wedge pressure clinically.
Is that clear? Whereas pulmonary edema, if
it was by itself without ARDS, will have an
increase in pulmonary capillary wedge pressure.
And the other big one here was the low cardiac
output that we saw with ARDS in the setting
of sepsis and cardiogenic issues.