COVID-19 Ventilator Course: Learn or Review Mechanical Ventilation (Free at MedCram.com)

COVID-19 Ventilator Course: Learn or Review Mechanical Ventilation (Free at MedCram.com)


as hospitals across the world are dealing
with more patients in respiratory distress from COVID-19 we wanted to
offer this course as a refresher on mechanical ventilation or a way to learn
the key concepts for the first time we’ve received a lot of comments from
medical professionals physicians pas and peas nurses students that don’t have
significant experience with mechanical ventilation but who want to be ready if
called upon to help the ventilator teams in the critical care setting or maybe
you have ventilator experience but want a refresher course to help teach these
skills to others this video series is a collection of previously recorded videos
and we’ve added some new kovat 19 specific ones as well part 1 of this
course covers the core concepts of mechanical ventilation we’ll start with
an introduction to the ventilator and compliance pressure volume relationships
and the different ventilator modes then I’ll illustrate plateau and peak
pressure peep and other vent settings or review the pathophysiology of acute
respiratory distress syndrome and how kovat 19 causes fatalities will then
discuss vent changes and COPD we think the discussion about Co P will be
relevant because they’ll be patients who will come down with kovat 19 who have
COPD we’ll finish part 1 with a checklist
that you can use to see if a patient’s ready to be liberated from the
ventilator in part 2 of this course will progress to vent pearls tips clinical
pitfalls more advanced strategies involving heart lung interactions
ventilation in metabolic acidosis more on COPD and finally bi-level ventilation
we’re committed to keeping this course free please share it with anyone you
think may be interested be well and thank you for joining us cram welcome to
another make cram lecture we’re going to talk about mechanical ventilation and
this is meant to be a introduction to mechanical ventilation so if you’ve
never done mechanical ventilation before we’re going to introduce you to the
basics so you can go in and actually feel competent about managing a patient
on the ventilator this is often a daunting task because
typically these patients are critical but actually the basics are fairly
graspable and series that’s gonna actually go through
a number of different lectures and we’re gonna start with the basic starting
right now the first thing you’ve got to know is you’ve got another definition of
some of these things okay so you’ve got the patient then you’ve got this thing
coming out of their mouth that’s the endotracheal tube we’re gonna
show this a little bit more later and then you have it hooked up to a big
machine with a bunch of knobs on it and dials and output this is what we know as
the ET tube that’s the endotracheal tube and then
finally you’ve got the actual ventilator that’s important to know because
sometimes people are intubated that means we’ve put a tube down into their
mouth because they need airway protection in other words because they
can’t protect their airway they can’t protect liquids and solids from going
down their airway work that stuff shouldn’t go and because of this it’s
not too comfortable we’ve got to sedate them and when we sedate them we’ve got
to put them on a ventilator so that might be one reason why we would have to
do this the other reason is because they can protect their airway okay but they
just can’t breathe on their own they’re struggling to breathe and so we help
them out with the mechanical portion of breathing and that’s where the
ventilator comes in and the way we deliver that is through the endotracheal
tube so it’s kind of important to know what a endotracheal tube looks like and
the basic is pretty much the same all the way around it’s this long tube kind
of looks like this and that’s the part that connects to the ventilator this is
the part that goes inside the patient and actually you’ll see that there is a
balloon on the end of that endotracheal tube and the thing that allows you to
blow it up it’s a little thing that goes up the pilot part comes out and it’s
like a little pilot balloon that you can kind of feel what the pressure is and
then there’s a little port where you can inject air into it so when this goes
down and you intubate somebody goes into their mouth past their vocal cords
specifically and down into the trachea so the vocal cords usually end up about
right here and so this is going down into somebody’s trachea okay and then
usually it branches off you’ve got the left and the right mainstem bronchus
okay so here you have the endotracheal tube going down now this balloon gets
inflated here so that stuff that might make it down here doesn’t go past and go
into the lung this is called airway protection and we blow up the balloon
here after we intubate them to make sure that that happens
now in some versions of this they’ll have like a little device right here
that also comes out the purpose of that is to suck secretions that might come up
and go out and at subglottic suctioning that’s kind of an option but this is the
basic anatomy of an endotracheal tube now of course we just talked about the
ventilator that’s got a bunch of buttons and whistles and things we’re gonna talk
about in a little bit okay so going back to our patient again we’ve got our
endotracheal tube we’ve got our ventilator so what’s the purpose of this
ventilator the purpose of the ventilator is to maintain homeostasis between the
dew gas concentrations that we’re talking about here which is carbon
dioxide and oxygen okay so oxygen is being put into the patient and carbon
dioxide is coming out and for the most part we want to keep those close to
normal there’s some exceptions to that here’s the point though there’s many
different ways to put air into somebody okay we can say we’re gonna put air into
somebody based on volume so we’re going to put a certain X amount of volume into
somebody and then let it come back out that’s one way of doing it another way
of ventilating somebody is saying we’re going to inflate them to a certain
pressure so we’re gonna have this ventilator put a certain amount of
pressure into the patient and then when that pressure is released then it’s
gonna come back out so we can do that now we can do it at a certain rate we
can do this fast and we can do it slow okay so in other words how many breaths
per minute we could also adjust the flow rate so in other words yes we can port a
certain volume in but we can give that volume slowly or we can give that volume
very quick the other thing that we can do is we can
decide how much pressure to leave in there at the end of when we put the air
in and then we can decide how much pressure to leave in there after we’re
done putting the air in finally we can decide how much oxygen we want to put in
there we can put a lot or we can put a little now just to further complicate
this just to kind of see where we’re going with this we can have the
ventilator be in charge of when the patient gets a breath or we can have the
patient be in charge of when they want to get a breath so think about all of
these different variabilities and now you can quickly see how there are so
many different ways that you can ventilate somebody and each one of these
ways is a different mode of ventilation you may have heard of these before
like AC or simv or pressure support or CPAP these are all different modes and
we’re going to go through some of these modes and show you how this is working
okay so here’s our system over here we’ve got the ventilator here we’ve got
the tubing that goes to the endotracheal tube down into the lungs and we’ve got
our balloon here filled with air to make sure nothing else gets down there and
we’re ventilating our right lung and our left lung so let’s talk about the first
mode of ventilation and this will become important later
the first mode that I want to talk about is AC okay the other way we call it as
assist control the other name for it also is continuous mandatory ventilation
or CMV now this is the most common mode of ventilation that you’ll see
especially on a medicine floor or medicine units the key here is that the
patient triggers the vent how does that happen well the patient takes a breath
in and therefore there’s a negative pressure here which causes a negative
pressure to be sensed here at the ventilator the other way you could sense
it is by flow if there is a flow that actually goes through here by the
negative pressure now as soon as the ventilator picks
on that negative pressure it’s going to deliver a specific volume and so there’s
an actual dial on here where you can actually turn the knob to a specific
volume or you can enter it in and that volume can be anywhere from 500 CC’s all
the way up to 600 cc’s usually the ideal way of ventilating somebody would be
around eight milliliters per kilogram ideal body weight anyway whatever that
volume is it’s going to deliver that specific volume in AC mode ventilation
now the patient can trigger it you could also set up a backup mode or a rate what
does that mean if I set the rate to for instance twelve because there are twelve
five-second intervals in one minute that means every five seconds the ventilator
will give a breath to the patient of a specific volume only if the patient does
not take a breath if the patient is breathing above 12 then the ventilator
will only give breaths when the patient triggers it by trying to take a breath
in in other words if you set the mode to AC set in a volume and set a rate of 12
the patient can never breathe less than 12 times per minute now there’s
something that you should understand about this which is very important you
may recall from chemistry an equation that says P V equals n R T now in this
system temperature is constant R of course is always a constant n is a
constant and so the thing that you must realize is that pressure and volume are
inversely proportional to themselves in other words as the volume of a gas goes
up the pressure goes down if you have the same amount of gas however the other
way of looking at this is compliance which I’ll abbreviate as a C compliance
is equal to the change in volume over the change in pressure which means to
say if the pressure changes a little bit and
the volume changes a lot then you have a very compliant lung if you don’t have a
very compliant lung it’s gonna take a lot of pressure to make just a small
amount of change here’s the point the point is is that these set of lungs have
a specific compliance and if you are delivering a specific volume into these
lungs you are going to get a specific pressure after you deliver that volume
that pressure can change depending on the compliance the point of this is is
that you need to have a readout that tells you what the pressure is in that
lung so you can know what the compliance is so in other words in this mode of
ventilation you set the tidal volume and the ventilator will tell you what the
pressure is so you’re setting the tidal volume you’re setting how much volume of
gas is going to go into the lung and based on the compliance of the lung it
will tell you what the pressure is if the compliance of the lung goes down
then typically you’ll have higher pressures if the compliance of the lung
is very high in other words a very compliant lung then your pressures are
going to tend to be on the lower side now let’s make this converse to pressure
control in pressure control what we’re doing is we’re setting a pressure in
other words we’re going to decide how much pressure we’re going to ventilate
this patient with and so as you can imagine if we’re setting a pressure
there is a specific compliance to this lung depending on what state it is in
and if we set a certain pressure if the compliance of this lung is very low then
you can imagine we’re gonna have lower volumes however if the compliance of
this lung is very high then we’re gonna have higher volumes because remember
compliance is equal to the change in volume over the change in pressure so in
pressure control you can also have the patient or time triggering a set
change in pressure and depending on the compliance the volume can change and so
the key here is that you need to have alarm setup and you need to know and
understand what those alarms mean what could happen here let’s for instance say
in a pressure control situation where you’re giving a specific pressure if the
compliance of these lungs somehow drop precipitously all of a sudden because of
some pathology which we’ll get into you will notice that the volumes will drop
you would want to know that and so you could set a alarm on the lower side of
the volume so that if the volumes did go down an alarm would go off saying that
you’re not ventilating conversely if you were back in our previous mode which was
assist control and you’re setting a certain volume if the compliance of the
lung dropped in that situation then as you would realize the pressure would
start to go up because you’re trying to put a set amount of volume into a low
compliant lung and when that happens the pressure goes up the pressure would then
trigger an alarm so the point here is in pressure control you’re setting a
pressure and your output to Reed is your volume in AC it’s the flip of this so
when we come back we’ll talk about the pressure volume relationship and a few
more modes of mechanical ventilation you