Okay, welcome to another Med Cram Lecture.
We're going to talk about liberation from the ventilator.
Now, this is kind of an interesting term and the old term for this was weaning from the
ventilator.
Weaning from the ventilator.
Well, we used to use this in terms of getting people off ventilators, now, we just kind
of use that term when we're talking about breast feeding so the more appropriate term
is liberation from the ventilator.
We try to use this as much as possible, so we've talked about, in our former lectures,
about putting people on the ventilator using the endotracheal tube, the vent settings,
how we come across with the vent settings.
What they're trying to be doing and now we're going to talk about how do we get them off
and what do we look for when people are on the ventilator?
Well, the first thing I want you to be aware of is when anyone is on a ventilator, you
really want to make sure that every single day you are lifting sedation
and number two, when you've lifted that sedation, you're doing a weaning trial.
Now, I just used that term weaning.
You're doing a liberation trial.
The purpose of that is to see whether or not your patient can liberate themselves from
the ventilator.
Can they come off the ventilator and if you don't do this every single day, the research
has shown that people stay on ventilators longer than they should be and this is not
a good thing because you can actually get pneumonias and complications from being on
the ventilator for too long.
Of course, there are exceptions to this rule here.
Obviously, if the patient is on an FIO2 of more than 45%, that's probably a good reason
not to even bother doing a set of parameters to see whether or not they can come off the
ventilator.
The other thing of course, is if they're very unstable or if they're on high amounts of
vasopressors.
Those would be exceptions to that rule but generally speaking, when someone is on a ventilator,
in fact, there are protocols in intensive care units to make sure that you are lifting
sedation on a daily basis.
It's called a sedation holiday and they're also doing what they call liberation or weaning
trials.
This was made very clear in a recent article that was published that was called the "Wake
Up and Breathe Trial".
This showed that practicing this type of a protocol was very important.
Let's say your patient has had their sedation lifted and you start a weaning, or a liberation
trial, what are you going to actually do and see whether or not the patient is going to
succeed and come off the ventilator?
Basically, what you are going to do is you are going to do something that is called an
SBT.
That is known as a spontaneous breathing trial.
If the patient is on AC ventilation, pressure support, or SIMV or some other supportive
ventilatory mode, you're going to switch them to some sort of combination of, in most cases,
pressure support, which means they're getting a certain amount of pressure with every breath
that they take in.
They might also be on a specific peep and that's usually around five or so.
The other mode that you could do is something called tube compensation.
Simply, this compensates for the resistance of the tube.
The bottom line is that there are several ways that you can do a spontaneous breathing
trial.
What you want to do is get the support as low as physiological and see how the patient
does over the next one, two, three hours.
Then, draw a blood gas.
An ABG.
Generally speaking, if the patient looks like they're comfortable.
Looks like they're able to take in some deep breaths.
They're not breathing too quickly, we'll get into some of those parameters later.
They've got a blood gas that look pretty good, what I mean by pretty good is it's usually
greater ... The PH is greater than 7.35 and it's less than a PCO2 of 45 and the PO2 is
in a reasonable range, so somewhere 60 to 70 or above and the patient looks comfortable,
then that's a good spontaneous breathing trial.
Some of the other factors that we see, let's run down those.
There's something called the rapid shallow breathing index.
This is also known as the Tobin Index.
Named after the gentleman who came up with this and it's basically the respiratory rate
divided by the total volume.
The respiratory rate is in terms of breaths per minute, so you can put down here, the
respiratory rate which would be, let's say 20 and the total volume, which is in liters.
You'd want to put that maybe if it's 500ml, then you would put a .5, so 20 divided by
.5 is going to be about 40.
Now, the key with the rapid shallow breathing index, as you can see from this equation,
very simple equation.
The higher the respiratory rate goes, the higher the RSBI and the lower the total volume
goes, the higher the RSVI.
That's not a good situation.
If you see somebody coming off the ventilator and they're breathing rapidly and shallow,
if it is above about 105, that's not usually a good sign.
You want patients to be breathing slowly and with deep breaths.
If the RSBI is less than 105, that's a good sign.
That's a positive sign.
Other things to look for is if the NIF is around negative 30.
That's usually a good sign that they're able to take a good deep breath in.
Some other things that you might see is a minute ventilation of less than 15 liters
per minute.
This just shows that the metabolic requirements of the patient are not so demanding that they're
going to have to breath very fast when they get off the ventilator.
That's probably the reason why they got on the ventilator in the first place.
If the minute ventilation is less than 15 liters per minute, that's usually a good sign.
All of what we've just talked about here, since the beginning of this video, is in terms
of what are the mechanics of ventilation and is the patient ready to come off the ventilator,
so these are all numbers that you should look at.
I would say that the most important that we've talked about so far is simply, what does the
blood gas look like at the end of a spontaneous breathing trial, after about two or three
hours?
In fact, there are four things which I want to talk about.
There are four specific things on your checklist that you must say yes, the patient is ready
to fly, when they're coming off the ventilator.
Think about this as a plane taking off and you're going through a checklist of things
to make sure that everything is working before you lift that plane off.
The first thing, is everything that we've talked about up to this point is the mechanics
of ventilation good?
The way you can check this one off is if they have completed a spontaneous breathing trial
and they've got a good blood gas.
That would be a check.
The next thing is mental status.
In other words, is the patient mentally alert enough to protect their airway?
Remember now, sometimes this is the particular reason why they got intubated in the first
place, so if somebody comes in with a drug overdose, obviously their lungs should be
working fine.
It's just the brain that's running the lungs, isn't working fine and they may swallow stuff
and it may go down into their lungs and that is the reason why people get intubated.
Obviously, if it's a factor for them being intubated, it could also be a factor for them
being extubated.
You want to make sure that they can actually protect their airway before you take that
endotracheal tube out.
If they've got a good gag reflex and they're awake, they don't have to be deriving the
quadratic formula, but if you feel that they can protect their airway than that's a good
check there.
The next thing is secretions.
They may have a good mechanics of ventilation.
They may have a good mental status but if there are copious think secretions coming
up from the endotracheal tube that you don't feel this patient is going to be able to clear,
then you may need to leave the tube in.
If on the other hand, you think that they can, secretions are not a problem, then that's
a check.
The final thing that we check for is something known as an air leak.
This has something to do with the endotracheal tube itself.
Let me demonstrate what I mean by that.
If we've got a trachea, you know that when we put the endotracheal tube in, there is
a balloon that we inflate.
That's this green thing right here.
Now, when that balloon is inflated, it prevents secretions from going down into the trachea.
That's how we protect the airway.
Now, because of that balloon, there can be swelling that occurs and so you may actually
have such swelling in this area that when you deflate that cuff, in other words, when
that balloon is deflated and you put positive pressure into this lung, the air may not be
able to get out.
Normally when you deflate that balloon, air should be able to come out.
You should be able to hear that passing by the trachea.
You should be able to hear what we call an air leak.
An air leak is good.
It's positive.
It's a good sign, but if you've got tracheal swelling and you deflate the cuff and there
is no air leak, you do not hear any sound coming up in the patient's mouth, that is
probably because there is swelling and if you were to remove that endotracheal tube,
it is possible that your airway could be closed off.
That is not a good thing.
When you're ready to extubate, the last thing we do if all of these things look good is
we check an air leak.
If we hear an air leak, then all systems are go.
These are the four things that I look at before taking the endotracheal tube out of a patient.
This doesn't mean that nothing bad is going to happen to the patient.
That's why you watch very carefully when you extubate and you see what's going to happen,
but these are the four things that they've got to pass before I will take that endotracheal
tube out.
That is extubating.
Thanks for joining us.