Refractory means stubborn or unmanageable
or resistant to a process or stimulus.
That's what that word means
inside and outside of medicine.
resistant to process or stimulus.
Now, we say stubborn,
resistant to processor stimulus,
low oxygen in the blood.
So, no matter how we try to
ventilator oxygenate this patient,
we just can't make it work that
PaO2/FiO2 level is still too low.
Take a look at that Berlin
definition you see right there.
Remember we talked about
that in the beginning.
We talked about the
We've got the breakdown there
for mild to moderate to severe.
Now, which category do you think
refractory hypoxemia would fall into?
This is when we're in big
trouble for our patient.
So, that refractory hypoxemia is
low levels of oxygen in the blood
despite increasing the
delivery of oxygen.
It's rare, but very serious and a
life-threatening complication of ARDS.
So, is there anything we can do?
Yes, there's some things I'll
get to those in just a minute,
but I want to make sure you are
clear on what this definition is.
it's been defined as an increase in
partial pressure of
oxygen in arterial blood.
you already know that is PaO2.
So, in looking at as a increase in
the PaO2 of less than 5 millimeters.
If the fraction of inspired oxygen
the FiO2 is increased by 0.1 or 10 %.
Okay, so what does that mean?
Well, that means if I have a
patient who is on 75% oxygen, right.
So let's say you're
on a ventilator,
they're on 75% oxygen which is
higher than I would want them
to be look at that definition.
So if we increase
the oxygen by 0.1,
then I would bump that
patient up to 85%.
But the PaO2 change I
saw was less than 5.
So, if my PaO2 before this
ventilator change was set at 75
when I Increased it to 85%
FiO2 and only bumped up to 77
that would be considered
So for practical purposes, there's various
criteria been applied most commonly
is considered as one of
these other things, right.
Because that was a lot for
me to talk you through.
Look at these,
it's either a PaO2 of less than 60.
Hello, because remember
normal is 80 to 100
or it's the defiinition you see
here that we just talked about.
PF of less than or equal to
100 on FiO2 of 80% to a 100%
with peep positive end pressure
of greater than 30 centimeters.
Okay, this is wow.
We're going to add on to that
a plateau pressure of 30.
Now, if your eyes just
glazed over and you said,
I don't even know what
you are talking about.
That is okay, all right.
I just want you to know
takeaway point from this.
Refractory hypoxemia means we're doing
some pretty fancy ventilator settings
and oxygen support and we're not making
that big a difference in the PaO2.
So, easier than memorizing
all this is just think
been an easy one to go with is
PaO2 less than or equal to 60.
And refractory means
no matter what we're trying, it doesn't
seem to be making a difference in the PaO2.
Why are we looking
at that number?
Because the PaO2 helps us quantify
the lungs ability to get oxygen
from the lungs into
the blood stream.