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