welcome to another video this is Mike Hansen and in this video I'm going to talk about do
ventilators actually save patients lives so as a lung doctor and an intensive care unit doctor I
see patients in the hospital who are the sickest of the sick patients come to the intensive care
unit who are on the brink of death and sometimes they live and sometimes they die based on a recent
study that came out only a few weeks ago only 14 percent of people who have covid 19 who require
a breathing tube end up surviving so Covid 19 patients who end up getting ARDS in an intensive
care unit who need to get a breathing tube only 14 percent of them end up surviving but let's talk
about why that is in order to understand why we have to know more about Covid 19 and how it
affects the lungs we have to understand mechanical ventilation and we have to understand the bridge
between those two things ARDS acute respiratory distress syndrome let's start off by talking
about why does someone need a breathing tube in the first place because there's only one of
four reasons why someone needs it and usually it's gonna be either 1 2 3 or 4 these reasons why I end
up someone why someone ends up getting intubated with mechanical ventilation the first one is
gonna be hypoxemia or hypoxia meaning low oxygen levels now hypoxia by itself doesn't necessarily
by someone our breathing tube when someone has low oxygen levels and we can't get those oxygen levels
up by other means such as with a nasal cannula or high flowed or high-flown use a cannula or with a
BiPAP mask when people don't get better with your oxygen we have no choice but to put that
breathing tube in and have them on a ventilator so that's one reason another main reason why
we put a breathing tube in is because someone's carbon dioxide levels are too high meaning their
co2 levels so a couple of common scenarios where that's an issue is when for example someone has a
drug overdose and they're not breathing because of that drug in their system well in that case
they start to accumulate high levels of co2 if they're not gonna breed that breed that co2 off
on their own they need a breathing tube in order to do that another common scenario is with COPD
emphysema where they just not able to breathe off that co2 because they're trapping air within their
lungs and eventually they need a breathing tube in order to accomplish that the third scenario
is when someone has a high work of breathing so for example let's say someone who's having
a severe asthma attack or severe exacerbation of COPD for example in that case lots of times they
are breathing at a rate of 30s to 40s meaning 30 times per minute 40 times per minute and they're
also using what we call accessory muscles of breathing so normally when we breathe we're just
using our diaphragm that does most of the work but when someone's really working hard they're
also using their abdominal muscles they're using their sternocleidomastoid muscles here and they're
also using the muscles that are around their ribs so that's three reasons the fourth reason why we
put a breathing tube in someone is because they're so obtunded for whatever reason that they're not
able to protect their airway meaning for example let's say someone is very very drunk to the point
where there's totally unconscious in that scenario they could vomit whatever's inside their stomach
probably what they're drinking and then it goes up their esophagus from their stomach and then
it goes down into their trachea the windpipe and down into the lungs and that can cause a
severe inflammatory reaction within the lungs it can cause aspiration pneumonitis can cause
air yes so that's the fourth scenario another example of the fourth scenario is let's say
someone has a big-time stroke where they just lose consciousness something like that and they're not
able to protect their airway it's the same thing those patients will need a breathing tube in order
to protect their airway so those are the four indications for a breathing tube so with
covid 19 patients who have ARDS their oxygen levels are too low and usually they're breathing fast
where their work of breathing is up as well and so really they have at least one probably two
reasons to be intubated with the Covid 19 patients for the ones who do get air - yes what happens is
the virus latches onto these ace two receptors within the body within the lungs and ultimately
it triggers this crazy chaotic inflammatory reaction within the lungs it's primarily
within the lungs but the immune system affects the entire body and the whole reaction affects
other organs as well so all the organs or most of the organs will become affected but the main
organ that's affected is the lungs so acute respiratory distress syndrome it has a lot of
different causes not just covid 19 but also if you remember with the vaping lung injury that was the
cause of ARDS as I mentioned before when someone aspirates causing aspiration pneumonitis that can
cause ARDS pneumonia in general whether it's bacterial or viral that can cause ARDS and in
order for us to make the diagnosis of ARDS it's basically four criteria to meet that diagnosis
it's one having low oxygen levels specifically not specifically specifically a po2 ratio of less than
300 so what that is is the air that someone inhales that's gonna be a certain percentage
percentage of oxygen so this air right here is 21% oxygen when we're giving someone more oxygen
in the hospital supplemental oxygen that's higher percentage of oxygen so whatever they're breathing
we determine how much oxygen is in that air that they're breathing that's going to be your fio2 now
when we do an arterial blood gas meaning we stick a needle in the artery and then we sample that
artery send it off to the lab and we measure the oxygen within the artery we can determine exactly
how much oxygen is within your arteries so what we do is we divide those two that's how we get
the ratio fio2 is how much you breathe in and then you have the oxygen level the po2 in the blood so
the po2 divided the fio2 that's gonna give you a certain number it's gonna be a certain ratio and
if that number is less than 300 that meets the criteria for a yard yes so that's one criteria
the other country criteria is if it's a cute meaning if this process happens quickly within
a couple days usually it's ours the third criteria is when you have bilateral fluffy infiltrates on
chest x-ray or the bilateral patchy ground-glass opacities better seen on the CT scan and then the
fourth criteria is we have to determine that all this inflammation and x-ray findings in
the lungs are not due to the left side of the heart not failing so we get an echocardiogram
an ultrasound of the heart and determine if that left side of the heart is functioning properly so
if we see that left side of the heart functioning properly we can say that this is gonna be aired
yes as long as all those other criteria are met so we know what ARDS is now the thing is can
we do something to treat it and the answer is yes there are a few keys to managing patients who have
ARDS in our on mechanical ventilation the first key is actually to use low long tidal volumes
the way that I'm breathing right now I inhaled normally and I exhale normally the same way that
you're breathing and that's called tidal volume and for most people that's around 500 CCS or so
that's about half a liter and when we do tidal volumes for patients on mechanical but mechanical
ventilation who have erred yes we shoot for lower lung volumes the exact scientific answer is 6 cc's
per kick per body weight and that usually ends up coming out to about 300 range 300 cc's for women
and 400 range meaning 400 CCS for men so that's lower than your typical tidal volume that you
and I are breathing and because that's lower than what we're breathing it's uncomfortable for the
patient so lots of times we have to give patients sedation in order to make them comfortable in
order to breathe with that lower law Title VII now sedation by itself isn't always enough some
patients will require paralysis meaning we have to give a medication that causes them to be paralyzed
temporarily and what that does is it allows the patient to be synchronous with the ventilator if
we don't do that they won't be synchronous with the ventilator and that's actually not conducive
to them getting better so not all patients require paralysis is actually generally speaking a pretty
small percentage but when the ARDS is typically severe or moderate to severe we do sometimes have
to give paralytic agents now you've probably seen some horror movies where someone was paralyzed
but they're awake so we try to avoid that at all cost we give them sedation whenever we give it we
give them a paralytic that way they're not their mind isn't awake during that time so the other
key to managing patients with ARDS is having a high peep level meaning positive and expiratory
pressure all that is is if you were to take a deep breath and then right when you're about
to let that breath go out you cover your mouth and your nose and you'll feel that with inside there's
a pressure inside your chest and that pressure that's in there when you do that is your peep
so the studies have shown that ARDS patients who have higher peep levels and we dial that
on a ventilator when we have higher people levels on the ventilator for patients with the ARDS they
have better rates of survival the only downside is you have to be careful you don't give someone too
much peep because that can puncture their long and their long ends up becoming like a flat tire and
that's not good that can make the situation much worse so there are a couple other things that we
often do for air - yes that may improve air - yes when someone has severe a RTS we typically give
steroids so in the form of corticosteroids meaning solu-medrol which is methylprednisolone the other
thing we do sometimes is prone positioning we do that if they have moderate to severe ARDS
so prone positioning means okay when you're in a hospital you see someone lying in a bed they're
always lying on their back right well the prone we flipped them over so they're lying on their
chest and what that does is it takes the weight of the heart off the posterior meaning the back
of the lung regions and it also lifts a little bit that pressure off the diaphragm in the lower
lung regions so what you end up getting is more compliant lungs meaning the lungs are
able to expand deflate and inflate back and forth easier sometimes to do other modes and mechanical
ventilation which gets pretty complicated so I'm not gonna dive into but if you want to look it
up there's airway pressure release ventilation there's inverse ratio ventilation typically not
something that we do but sometimes we have to when we have no other choice to try and
get their oxygen levels higher so with COVID 19 patients who have ARDS who require mechanical
ventilation with a breathing tube their average time on the ventilator is 17 days and like I
mentioned early in this video only 14% of those who get the breathing tube actually survive