okay hi everyone my name is lahiru and here i've got andrew and we're just going to discuss why
would you have low fio2 in really unhealthy lungs and so the question i'm posing to andrew here
is you know say you've got someone really bad maybe they've got an evolving pneumonia maybe
that just had a recent aspiration or evolving bronchospasm now i'm going to make the argument
that if you have this case and they've rushed to theater it's in this case you might actually
want to have a low fio2 so let's try to explore that so um good so first of all i'm just going to
draw you some pretty dodgy looking lungs here imagine that these lungs are a little bit bad
but they could get worse now there's going to be two situations let's say you've got a four
five
is just arbitrary arbitrary numbers yeah if i start with a low f1 let's say
forty percent and the stats are not great for their okay not important versus say eighty percent
the stats are still that ninety percent because the lungs are equally as bad
now so ask andrew what happens what happens to the sats in this situation in this situation
if the lungs get a little bit worse so there's like an evolving pneumonia
it's an evolving bronchospasm whatever it is now what happens in you know say
two minutes ten minutes whatever it is as long as you get a little bit like what happens here
so expect that the stats here are gonna go down fantastic so the satellites are going to know
what what does this that sort of get probably they might go down a little bit but probably not much
now let's see the lungs get a little bit worse what happens as time moves on so again these
will go down obviously we're going to intervene then uh here and on this side
it might go down a little more yeah because you got a lot more reserve you can do that much so
keep going so let's say they go to 80 percent and then sets might at this point just go down
a little bit and then here let's say 75 percent and now they finally go down somewhere that i'm
really concerned about so that's as the evolving process gets worse and worse my lungs get worse
and suddenly my stats are dropping these two situations and what's interesting is andrew
when would you if you had the if you had the sats on 80 when would you start treating this problem
so earlier around here yeah for this one so that's your 40 percent at time 2 as soon as it drops
suddenly you start treating so you increase your fio2 you have lots of time because now you
know put my si2 straight to 100 and i'll have you know say 5-10 minutes before the lungs get really
worse and i'll start treating straight away but i'll identify it at this point here at time 2.
if i've got my saturn 80 yeah where do you where do you start intervening
so if my stats are too high that means i'm starting to be in here which is really bad right
because now i have no room to move even if i increase myself 100
i don't have 10 minutes i've only got a couple of minutes to sort my things out
and solve the problem so that's my argument for buying my fire tube lower in sick ones
but still keeping the patients safe you know so they've got a knife knife or some sats or above
that enables me to really uh have to identify when there's a problem
increase the fio2 and have lots of time to solve that problem now this also makes sense because of
the hb o2 dissociation clearly everything that's the sets on that axis the key virtual analysis and
it's clearly looks a little bit like this if i'm running at high here you know high office high co2
if the patient's there in the lung deteriorate the sets don't drop because we're not measuring
the avg's constantly we're not able to see that the ph2 is actually dropping in this situation
here so in this situation here it drops and drops and drops until finally we see a drop
but that's when we've got very little reserve in this situation here i'm running a patient
just at the cusp of you know over here and so as soon as something goes wrong i see it and i see
a noticeable change so that's my argument why we should run lower fis in in sick lungs so that we
identify exactly when the problem is going to come and there's an anesthetic context obviously not
in an icu context or other context like in the in the ward very specific context that's my argument
you