00:01
Refractory means stubborn or unmanageable
or resistant to a process or stimulus.
00:07
That's what that word means
inside and outside of medicine.
00:11
Stubborn, unmanageable,
resistant to process or stimulus.
00:17
Now, we say stubborn,
unmanageable
resistant to processor stimulus,
low oxygen in the blood.
00:25
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.
00:36
Take a look at that Berlin
definition you see right there.
00:39
Remember we talked about
that in the beginning.
00:41
We talked about the
PaO2/FiO2 ratio.
00:44
We've got the breakdown there
for mild to moderate to severe.
00:48
Now, which category do you think
refractory hypoxemia would fall into?
Right, severe.
00:55
This is when we're in big
trouble for our patient.
00:58
So, that refractory hypoxemia is
low levels of oxygen in the blood
despite increasing the
delivery of oxygen.
01:06
It's rare, but very serious and a
life-threatening complication of ARDS.
01:12
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.
01:22
So physiologically,
it's been defined as an increase in
partial pressure of
oxygen in arterial blood.
01:29
Yes,
you already know that is PaO2.
01:32
So, in looking at as a increase in
the PaO2 of less than 5 millimeters.
01:39
If the fraction of inspired oxygen
the FiO2 is increased by 0.1 or 10 %.
01:47
Okay, so what does that mean?
Well, that means if I have a
patient who is on 75% oxygen, right.
01:55
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.
02:05
So if we increase
the oxygen by 0.1,
then I would bump that
patient up to 85%.
02:12
But the PaO2 change I
saw was less than 5.
02:17
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
refractory hypoxemia.
02:32
So for practical purposes, there's various
criteria been applied most commonly
is considered as one of
these other things, right.
02:40
Because that was a lot for
me to talk you through.
02:42
Look at these,
it's either a PaO2 of less than 60.
02:46
Hello, because remember
normal is 80 to 100
or it's the defiinition you see
here that we just talked about.
02:55
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.
03:09
Okay, this is wow.
03:11
We're going to add on to that
a plateau pressure of 30.
03:14
Now, if your eyes just
glazed over and you said,
I don't even know what
you are talking about.
03:19
That is okay, all right.
03:20
I just want you to know
takeaway point from this.
03:23
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.
03:34
So, easier than memorizing
all this is just think
been an easy one to go with is
PaO2 less than or equal to 60.
03:41
And refractory means
no matter what we're trying, it doesn't
seem to be making a difference in the PaO2.
03:48
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.