Airway pressure on the ventilator. Airway
pressure on the ventilator, what kind of issues
do you want to take a look at with this? Well,
the ventilator will support out a peak pressure.
So what does that mean? Well, you are going
to now introduce positive pressure, aren’t
you? You are introducing positive pressure
throughout the airways and then eventually,
what is the objective? The alveoli. Keep that
in mind. Let me show you a figure here that
is going to give you a nice little analogy
to exactly that. This is the airway pressure
measured in the endotracheal tube with each
breath. Listen, airway pressure is what you
are focusing upon here, I will show you. Now,
more important though is the pressure in the
lungs, in the plateau pressure, which is measuring
the distending pressure of whom? The alveoli.
So, for example, you take a look at this image.
In this illustration, shows you a bubble and
that then represents the lung or the alveoli.
But then you actually have the airway to
the left proximally. So, you can increase
pressure in two places. That airway pressure
or the lung. Think of this as kind of being like
a balloon. So, you have a straw in the balloon.
The pressure in the balloon is more important,
that is the lung, than the pressure in the
straw, isn’t it? But in the mean time that
you need to make sure that you are able to
properly measure the pressure in the airway.
So the goal of this is to minimise the trauma
to the lung leading to further lung injury
or even perhaps, remember, if you increase
the lung volume so much, you might actually
introduce some type of pneumothorax. Something
like a tension pneumothorax. What does that
mean? Well, that is your ball and valve effect.
A simple analogy there. You put air into a
football. Air doesn’t leave. The football
is the lung, tension pneumothorax. You are
putting air into the pleural cavity. Air
is not coming out. What are you creating?
Tension. Keep that in mind. We will have that
discussion when the time is right. In ARDS
the goal plateau pressure is less than 30
cm H2O. You need to know the units that you
are gonna use here for pressure, specifically.
Complications of mechanical ventilation. Lot
of this should be pretty straight forward, but
nonetheless, let's make sure that we are
clear. While you put in endotracheal tube,
understand that there might be organisms that
you are introducing into the pulmonary system.
Not good. What about these organisms? Often
times, resistant. Scary. Pneumothorax, we
talked about, mean to say that you have enough
pressure. At some point in time, there might
be a little bit of tear of your parenchyma
in which air then escapes into the pleural
cavity upon inspiration, it doesn’t leave,
often times, tension. We will talk about auto
PEEP coming up and that will make perfect
sense to you. Remember once again, as you
increase the pressure at some point, it may
then cause barotraumas. Tracheal damage. You
literally are going, well, might break a couple
of teeth when due intubation and you might
actually introduce lesions into the trachea.
If it lasts two weeks or longer, your next
step of management, so that you avoid further
damage, a tracheostomy. Critical care, always
worry about myo or perhaps neuropathy.
So, mechanical ventilation complications are
things that you want to keep in mind. Okay,