Ventilator Associated Pneumonia (VAP) Explained Clearly | Part 1
28
August

By Adem Lewis / in , , , , , , , , , , , , , /


welcome to our talk on ventilator
associated pneumonia we’re going to get started with looking over some of the
objectives that we’re going to cover in this lecture series so the first
objective is that we’re going to identify or ID the epidemiology the
pathophysiology detection and the risk factors for vApp number two is we’re
going to identify the risk reduction strategies and number three we’re going
to identify the pitfalls of implementation and then finally for
number four we’re going to identify the areas of controversy so there is
controversy because this is a burgeoning field in terms of research ok the first
thing that we really want to attack is the definition of vApp and really what
is the definition of vApp or ventilator associated pneumonia basically it’s a
pneumonia that arises more than 48 to 72 hours after endotracheal tube intubation
ok so you really can’t make this diagnosis on admission unless the
patients coming from another facility where they were intubated more than 48
to 72 hours before so in terms of this it’s just simply looking up at the time
when the patient was intubated so the timeline is pretty easy the part that’s
difficult is figuring out the pneumonia portion so what exactly is a pneumonia
now typically when we think about pneumonia we think of a fever we think
of an increased WBC count and we think of an infiltrate so you really should
have an x-ray that’s the cornerstone of diagnosis of pneumonia the problem is is
that some people may not get a fever and other people may be on
immunosuppressants or they may have a low white blood cell
count and then sometimes if they don’t have an immune system that is functional
they may not even have an infiltrate or what’s even more common is other things
may cause abnormalities on the chest x-ray that have nothing to do with an in
fact or an ammonia and so really what the
problem is in terms of definition is that the timing but is what is exactly a
pneumonia and as a result of that there’s been kind of two strategies that
have looked at this definitional issue one is known as the clinical strategy
and the other is known as the bacterial logic okay so here we have the non
invasive and this would be more as the invasive okay so what do these things
mean and we’re going to get back to these two strategies the clinical and
the bacterial logic be aware that there is sufficient not being quite clear
about how you define this pneumonia and so there’s been two strategies in the
literature the clinical which will you look at things clinically and make a
determination based on some criteria or the bacteriological which is the
invasive typically involving tracheal aspirates so where they put a tube down
the tube and get a tracheal aspirate and then culture it and see how many
bacterial counts they have okay so we’re gonna get back to that but first of all
let’s go through our objectives and let’s talk about the epidemiology so in
terms of epidemiology the the literature is about ten to twenty percent of
patients on mechanical ventilation so that’s about 6 to 21 times the risk of
contracting pneumonia okay so that’s the prevalence now in terms of mortality this can range anywhere from 13% to 55
percent depending on the literature that you look at the attributed more tality
which means you know how much can we say that the vapp was actually the reason
for the patient passing away is about 30 percent I don’t think you need to know
these numbers specifically but I would say that this is a serious issue and
that’s why we’re taking it very seriously not only in terms of
and life but in terms of financially the length of stay in the hospital increases
by about nine days so that’s an increase of about sixty two percent sixty two
percent increase what does that translate into in terms of dollars
that’s about forty thousand dollars per patient so if we can prevent ventilator
associated pneumonia you can see that we can prevent a lot of bad things from
happening let’s talk about how it actually happens okay so here is a
drawing of a larynx and trachea and bronchi with lungs and what I want to
show you is the endotracheal tube so as you know in intubation the endotracheal
tube goes down about two to three centimeters above the Carina up to about
five and as you know there’s a balloon that gets inflated to prevent secretions
from going down below into the lungs of course it’s not 100% but the
pathophysiology is that there’s aspiration of these oral pharyngeal
pathogens of gram negatives etc or leakage of these secretions containing
the bacteria which are up here in the oral pharynx and what happens is they go
down here and there’s pooled secretions which sit above this balloon and drip
down into the lungs and this goes into the lower respiratory tract now a lot of
the pathophysiology and epidemiology has come out of the latest guidelines from
the infectious disease Society of America and the American Thoracic
Society which were published back in 2005 and sort of the definitive paper so
if you want to do further reading please go to the American Journal of
respiratory and critical care medicine 2005 and look up the IDSA and 80s
guidelines everything that they say they give evidence for there’s
one evidence which is the highest level two which is intermediate and then level
three which is less and the evidence for which they say this is the cause of the
pathophysiology is level two evidence so pretty good but not randomized
placebo-controlled obviously the other thing that they mentioned is that
because this is a non living item here inside the patient biofilm can form on
top of this and it can be very difficult to eradicate so this is not foolproof
here the balloon is inflated but you can’t over inflate it and what you’ll
get is secretions which go down and that causes the vApp and so you can see that
a lot of the treatments that will talk about later or prevention strategies are
going to prevent this mode of transmission and causation of vApp so
now that we’ve talked about the epidemiology the prevalence the
pathophysiology let’s go back to what we were talking about before which was the
actual diagnosis or the detection of vApp and our dichotomy between the
clinical non invasive and the bacteriological
or the invasive so let’s talk about the clinical the clinical strategy is quite
simple what you really need is something that has happened to the patient after
48 to 72 hours of intubation and those things would be a new infiltrate but
several things could cause a new infiltrate and the way to make sure it’s
a pneumonia is by checking for a fever and an elevated WBC count but a lot of
things can cause that as well as we mentioned so you also should look for
purulent sputum if these things occur there’s a good chance that you’re going
to pick up a ventilator associated pneumonia so an ammonia that the patient
got while they were on the ventilator remember has to happen 48 to 72 hours
after intubation but there’s a chance that you could get a pneumonia and it
may not cause an infiltrate it may not cause a fever may not cause an elevated
white count and the patient may not have pure Yulin sputum so in other words
which you may have here are some false negatives
okay so this is going to be very specific but it may you may lose some
more subtle types of vApp now in contrast let’s go over to the
bacteriological here we use bronchoscopy that goes actually down into the lungs
and samples you could also use tracheal aspirants but classically it’s
bronchoscopy we actually sample secretions that are down in the lungs
and typically those should be sterile or certainly below a threshold now you know
that if I were to culture your skin I would get bacteria but your skin is not
infected and you don’t have cellulitis but in people who do have cellulitis the
bacterial counts are much higher on the skin indicating that there is an
infection and so what you could do is do a bronchoscopy in culture and set a
certain threshold like 10 to the 3 in terms of colony forming units and that
would determine whether or not there was colonization or whether or not there is
infection okay so the risk here is that you may have enough bacteria causing
colonization and you may call it a positive when in fact it would be a
false positive so here are the risk is false positive rate and you can see how
be very sensitive and there’s pros and cons on this in on both sides now the
thing is is that there’s some downsides of the bacteriological if you’ve changed
antibiotics within the last 24 hours typically it’s going to depress the
colonization rate and you may actually get a false negative in that sense there
is some evidence on the upside using this technique that if you don’t see
bacteria then you could stop antibiotics and there’s actually was a study that
showed that after two weeks mortality rates actually dropped also if you had a
negative colony forming unit threshold in other
words if you did the threshold then it was low is below your threshold then you
could say that the infection might be coming from another source maybe it’s
actually not from the lungs and that would spur you on to look for sources
elsewhere it actually could benefit the patient I think in terms of what you
should choose and certainly be IDSA guidelines say you could use either one
both are appropriate both are standard of care one has more advantages than the
other obviously if you don’t have somebody doing bronchoscopy then the
bacteriological strategy is going to be something that you can’t do the clinical
can be done fairly cheaply and it can be done just about anywhere so there are
advantages and disadvantages with either the key that I would say is that if
you’re going to track ventilator associated pneumonia rates in your
hospital you ought to stick with one definition and use it consistently
because how you define vapp can change your prevalence in your incidence of
that I’ll just say that there are a number of algorithms out there of the
diagnosis of ventilator associated pneumonia some of them are related to
vApp in immunocompromised patients and some of them are related to vApp in
immuno competent patients and so make sure that you look it up make sure that
you make a protocol and you stick with it that’s I think the key because you
really want to make sure that you don’t have a moving target you want to make
sure that you’re consistent in terms of your definition okay will join us for
our next video when we get into the risk factors for vApp you


6 thoughts on “Ventilator Associated Pneumonia (VAP) Explained Clearly | Part 1

  1. Great work Roger…Concise & yet highly educative. Will definitely think about getting a subscription in the future but the prices are too steep for me currently. Can we expect the rest of this series on youtube anytime in the future.

  2. VAP Pneumonia videos 2 – 6 (and quizzes after each video) at Dr. Seheult's website: www.MedCram.com

  3. Why is Health checkup so expensive in USA. In my country people get checked up all of their problems in individual department at just Rs. 60 (60 cent USA) with very good doctors. Can you believe it? I mean what do you even get with 60 cents?!
    Just wanted to share!

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