hey everybody Dennis Stanley here with respiratory Sensei and you may know me from Lindsay Jones today we're talking about a very nerdy calculation that's done for Respiratory therapists called the oxygen index and the reason why we want to talk about it is because it is a formula and a value that could be seen on the NBC exam at least the nbrc says they test on this so we want to know how to calculate it but also what it means and certainly what we would do about it on a certain value if the value is high how do we treat the patient all right so let's take a look at the oxygen index all right come with me as the Japanese would [Music] say we're here with the oxygen index and we want to learn how to calculate it but first let me just paint in your mind what we're actually calculating when you think of somebody that's on a ventilator and this will relate to only ventilator patients in rest therapy one of the things that we're trying to achieve is a very specific pao2 or a very specific oxygen level on the blood gas the question that the oxygen index answers is what does it cost in order to get that specific pa2 in other words we're having to use F2 and mean airway pressure and Peep and lots of different things on the ventilator and therefore to get a specific P2 is going to come at a specific cost and oxygen index is really looking at the cost to get a specific pa2 and so that's what we want to take a look at well in order to do so the first thing I want to do is kind of uh redirect your attention to something else and that is what if we were to look at something we'll make this up called a pay index and I were to ask you well how much do you get paid in other words what's the resulting pay you get for a specific amount of work and a job difficulty so if I said how much do you make you might say well I make $500 a week I don't know I'm just making that up now I could think that that's good pay or bad pay but I'd have to ask you a few more questions and one of the questions I'd have to ask you is well how many hours a week do you have to work to get that pay the other question i' certainly want to ask you is hey how difficult is that job are you digging ditches or are you sitting in a nice air conditioned office all right and so I could calculate your pay index by looking at the difficulty of the job or the cost or what it requires of you in order to make that $500 per week all right so I'm going to call that the pay index well that's really what the auction index is well as we take a peek at that so aution index is going to be looking at what is the cost in the numerator here going to be looking at two things we're going to be looking at the F2 or the oxygen percentage that you have to use is it low or is it high and then we're also going to be looking at the amount of peak Peak pressure the pressure but we're going to talk about it in terms of mean airway pressure be careful here you might see a map sometimes is also talking about mean arterial pressure that's a hemodynamic value we're talking about mean arterial excuse me mean mean airway pressure here and so the cost is do I have to use a lot of mean airway pressure do I do I have to expose your body to a lot of negative mean airway pressure in order to get that P2 that I want to so that's what we're really calculating so in the numerator we're going to take the o2% and times it by the mean airway pressure and then to know if that's good or not we're going to divide it by the resulting pa2 so it's a very simple formula we're going to look at its values and what it means but just remember this we're calculating the cost it takes to get to a specific pa2 and that cost is going to come in the form of some ventilator setting keep in mind also that as we look at cost the two things that we're worried about is having to use elevated levels of oxygen the higher we have to use the more dangerous that could be for the patient on any number of scenes for instance High oxygen can promote ARS High oxygen could also cause oxygen toxicity so it's a negative thing to have to use a lot of oxygen to ventilate a patient and to give them the right pao2 the other thing that we really care about is that when we expose the patient to a lot of airway pressure that has a negative effect as well now I won't go into this here a lot I'll talk about this in hemodynamics but let me just paint the picture for you just a minute if we have to give somebody a positive pressure breathing remember we're used to negative pressure breathing we drop our diaphragm and the air just comes in because we produce a negative pressure but on a ventilator we're having to positively push pressure in there and when we do that that pressure is going to go of course into our lungs with the air that we're putting in there the air or the gas is going to stay in our lungs but the pressure is actually going to go right through the tissues and it's going to go all over the inside of our body in other words it has influence well if a lot of pressure will surround itself around some of our bigger veins that are trying to return that blood home to the right heart then it has a tend to nullify the pressure difference and that decreases the Venus return or the Venus blood flow now again that's all covered in hemodynamics but I just want you to know that when we use a lot of mean airway pressure it comes at a cost it decreases our blood flow or return back to the right heart and if we have to use a lot of pressure we're going to expose the patient to dangers like barot trauma such as pneumothorax and actually acute lung injury that can lead to things like ards and that's why we care about understanding the cost in terms of the oxygen percentage and the mean airway pressure we times those together to determine the cost and to see if it's worth it to get that index value we're going to divide that by the pao2 all right with that in mind let's take a peek at that all right to do that we have to take a look at a patient and I have some values here that I'll I'll show you on the board and the first thing I want you to know is that if you're on the NBC exam they're going to give you a lot of values in the question and then your job job is to identify those values needed for an oxygen index so if you'll take a look at some of the values we have something like pH here and remember we're not looking at pH the formula requires o2% and the mean airway pressure and the pa2 therefore we only have to know those three things so if I go through the list well here's the pao2 so I'll pick that number that's important in this case it's going to be 100 and then we have the mean airway pressure in this case is going to be 22 and then the last thing I need is the o percent now this one's tricky if you're a restor therapist you certainly know how to do this they don't give us the oxygen in the percent form but they do give us the F2 and that's the same as saying 30% all right and so we have all our numbers now all we have to do is substitute those in in order to to progress towards the answer all right we're now going to look at another patient and we're going to look at some different values the first thing I'm going to do just like I did just now a moment ago is for this patient I'm going to select their values now I already know what I need to know I need to know the mean airway pressure the oxygen percent and the pa2 so let me select those values and then plug them in over here to do the actual calculation all right and so as we look at pa2 there it is so we have our pa2 and that's going to be 70 remember the P2 is going to go in the denominator here so I'm going to put 70 right here and then I need to know the mean airway pressure which is right here and I need to know the oxygen percent remember they have 0 4 cuz they're looking at f2 we're going to talk about it in terms of 40% and so all I have to do is say that the mean airway pressure which is 28 and I have to times that by 40 not4 because we're going to be looking at the percent version of that and as I do the math there as you do this math you can do 28 * 40 and then divide by 70 and then what you're going to get is a result of 16 and so our result here is 16 that's what our oi is the auxy index on this patient now is that good or bad well we don't know until we take a peak we'll talk about the values in just a minute but this person has an auction index of 16 all right well let's take a look at another patient all right here's another Patient First thing we're going to do is pick out our values and of course we have a P2 of 80 right there and then the mean airway pressure is 42 and it's taking 60% so let's just plug those values in all right the pa2 always goes in the bottom so we have got a PA two of 80 so we'll put that there and then the mean airway pressure is 42 and then we're going to multiply that times 60% all right so now all we have to do is that math we just go 42 * 60 and divided by 80 and we're going to get an oxygen index of 31.5 or I might just say 32 just to round that up all right so this patient has an oxygen index of 32 all right well now let's take a look at another patient okay okay here we are with patient number three now let's take a look at some of their values let's go ahead and pick those out well first of all we have a P2 of 50 that's not very good is it we're not getting a very good pa2 of whatever it's costing the pao2 is only 50 should be 80 to 100 in the artery so we know something's up already there and then look the mean airway pressure is 48 that's a lot of pressure and so we have that and then the F2 is 100 it's 1.0 but that's the same as saying 100% so let's plug those in and figure out what the auction index is for this patient all right well the pao2 always goes in the bottom and so we're getting a 50 here and then the mean airway pressure is 48 and we're going to times that by 100 and then all we have to do now is to do that math 48 time 100 ided 50 so we can get an oxygen index and what we get is an oxygen index of 96 okay that's the highest oxygen index that we've gotten so far and that means means that the cost for this patient to get just the P2 of 50 is very high what's the cost 96 I always think of costing money so it's $96 but as we go back to the other one remember the other one cost only $32 and the other one only cost us $16 not really dollars but you know what I mean and so this is what we're calculating we're actually just calculating the cost now that we've learned how to calculate the auction index what we to make of those values and what do we do for the patient so now we're looking at interpretation where we label the patient as normal or problematic and then also what could we do if the patient is problematic with their oxygen index and what does that mean remember the oxygen index is calculating the cost of getting a specific pa2 and we've calculated our patients so we'll take a peek of those in just a minute but just so we understand if we have an oxygen index of 20 or less then that's going to be considered normal that would be a patient of you and I that doesn't have lung disease if we were to go on a ventilator it would be pretty easy to get a PO to that we wanted to with very little mean airway pressure and very little oxygen percentage but if the oxygen index is rises above 30 then we're going to say you have some sort of acute lung injury what that is we don't know we might have even caused the acute lung injury with our ventilation or you may have come in that way but we can just generally categorize you and say you have acute lung injury but now take a peak that if we have an oi of greater than 40 we're going to say two things one that you do have an acute lung injury but also you have advanced to the stage of what we call ards so you have arts and then of course if you have ards then I should be thinking I should use the ards net protocol and I have permission to use a very drastic form of oxygenation called ECMO extracorporal membrane oxygenation and that's when we start taking the blood out and rerouting it outside the body to use an artificial lung in order to give its oxygen well so now here are the values let's take a peek at our p patients all right well first of all if you remember patient number one had an oxygen index of 16 and then we can look at our values here remember we said if it's 20 or less then the patient is basically normal and so what we're going to do with this patient is that we're going to say the patient is basically normal because they have an oxygen index of less than 20 all right now let's take a look at this patient patient number two had an oxygen index of 32 now that's not below 20 but but it's also not greater than 40 so it's kind of in that middle range what we can conclude from this patient and from this data on this patient is that they have some sort of of acute lung injury what is it we don't know we just know that acute lung injury is beginning to happen in their life and so that's how we could conclude from that patient and then of course we have our last patient patient number three they had an oxygen index at 96 now if we look at our values anything greater than 40 we're going to categorize that as ards and so we can say about this patient that they have ards and of course if they have ards we should be using the ards net protocol and so we'd want to be able to treat them that protocol of course is going to include things like using lower title volumes or lower f2s and managing peep appropriately so we just have to look at the protocol all right and then of course we also have permission to use something called ECMO or extracorporal membrane on oxygenation well that's what we need to know about the oxygen index look at what we've determined we use the formula to calculate the cost remember oxygen index is a cost the cost of achieving a certain pa2 on the patient and then depending on the value we can categorize that patient is either normal or having an onset of acute lung injury or they have acute lung injury and it has advanced ORS and we should treat them with the ards net protocol so on the NBC exam you can imagine what they could do with this they could just give you an auction index and make sure you understand how to categorize the patient and what you should do for the patient or they may make you pick out the values and calculate the oxygen index yourself and then either give them the index number or also go from there and interpret the results and maybe even decide what you should be doing for the patient well I hope that was helpful for you rest therapists who are preparing for the NBC exam you could also calculate the auxy index really on a patient if you have patients you should do that it might direct you and what you should do for the patient we do mostly see it using in a nerdy situation specifically for the NBC exam I'm Dennis from restr Sensei don't forget if you would please subscribe and like the video let let me know if I'm on the right track and also notify and share this video uh with others if you can and it really helps the channel it helps us to reach more people we hope to make the restor Sensei Channel a bang up success and reach a lot of people and bring restor therapy to the concepts to the whole Community inclusing not only to restor therapists but also to nurses all right thank you and we'll see you next time as the Japanese would say G Mar [Music]