# Medical Acid Base and ABGs Explained Clearly by MedCram.com | 7 of 8

so welcome to medical acid/base

part 7 we’re gonna go over some more questions and let’s just start off with

the next question which in this case is pH is equal to seven point two five $27.99 and a bicarb of 12 and the chem

seven shows a sodium of 140 a potassium of 4.0 a chloride of 96 and a bicarb of

12 so the first step again is to do the anion gap

what’s the anti gap so we add these two together and subtract from 140 so 96

plus 12 is 108 108 from 140 is equal to 32 definitely anion gap we now know

immediately that we have an anion gap metabolic acidosis and remember the

mnemonic for that as mud piles M for methanol you for your meid for diabetic

ketoacidosis but also alcoholic ketoacidosis and also starvation

ketoacidosis the P is paraldehyde eyes Ison eyes it or iron Ella’s lactic

acidosis is ethylene glycol or ethanol and SS salicylates so basically or and

the s could also stand for starvation ketosis as well if you wanted okay so

the anti gap is 32 which is a pretty sizable anion gap so what we need to do

next is calculate the Delta gap and the Delta gap is simply telling you above

and beyond 12 how much anion gap is there how

strong is this anion gap metabolic acidosis essentially so that’s simply 32

minus 12 which is equal to 20 what does that mean what is that 20 mean that

means there’s 20 units of conjugate base or conjugate anions floating around in

the blood that’s not accounted for here in the chem 7 and those 20 negatively

charged particles have to be balanced out we

the bicarb that was missing so essentially 20 units of bicarb had to be

taken away when they bound to the proton that came off of these 20 units in other

words what we could say is is if we took away the effects of this anion gap

metabolic acidosis and just took it away and see what else was there

we could add 20 to the bicarb and see what the bicarb would have been in this

case 20 plus 12 would have given us a bicarb of 32 what does that tell us

that means if we take away the known anion gap metabolic acidosis which we

already know is there what would the bicarb be while the

bicarb would be 32 and if the bicarb is 32 well let’s just write it down we

already know we have an anion gap metabolic acidosis we know we’ve got

that okay but if we were to take that effect away

since we know that Delta gap is 20 we know that that 20 sucked away 20 units

of bicarb let’s add back those 20 units of bicarb to the 12 that we have

currently and see what life would be like if we didn’t have that anion gap

metabolic acidosis what that would mean is our bike robe would be 32 and if our

bicarb was 32 that would mean that we also have a concomitant metabolic

alkalosis that could be like vomiting or Cushing’s disease or contraction

alkalosis or something like that so just by doing that we’ve already shown we’ve

already seen that we’ve we’ve identified two different metabolic processes that

are occurring okay so we know that so what’s the next step next step as we’ve

gone through is to look at the pH and the pco2 well we already know that both

are going down and we already have metabolic processes going so that’s

that’s easy we know that already the next thing is to do is to check to

see whether or not winters formula holds so obviously here we’ve got a metabolic

acidosis and a metabolic alkalosis which one do you think is stronger

well obviously the metabolic acidosis or in this case the anion gap metabolic

acidosis is stronger because we’re we’re acidotic

we actually acid emic okay so what we need to do is follow follow winters

formula for a metabolic acidosis and what does that say that says that for

every drop in the bicarb of one you should also get a drop in the pco2

of one and let’s see if that’s the case in our example here how much did our

bicarb drop by our bicarb went from 40 down to 12 how much of a drop is that

it’s about 28 actually it’s not from 40 down to 12

it’s actually from 24 down to 12 that’s the normal so if we went from 24 down to

12 that’s a drop of 12 how much did our pco2 go down by it went

from 40 down to 27 40 down to 27 is a drop of 13 and so what we see here is

that winters formula is followed perfectly for a metabolic acidosis okay

now let’s just say for some reason that the pco2 had dropped more let’s say it

had dropped 20 points for instance that would mean that instead of dropping just

13 points which it should have done if there was a pure metabolic acidosis

occurring or metabolic problem if it had dropped by 20 points that means there

would be an increased drop of the pco2 which would tell us that there must be

an additional respiratory alkalosis occurring and that would be an

additional diagnosis that we could put here

conversely if the pco2 had not dropped by 13 but it only dropped by 5 that

would mean that there must be a respiratory acidosis occurring because

the pco2 did not drop by the same amounts that it should have as predicted

by winters formula so basically when you’re doing this winters formula you’re

seeing if the pco2 drop is appropriate if it’s less than appropriate there’s a

additional respiratory acidosis if there’s an additional drop than what

should be predicted by winters formula then there’s a respiratory alkalosis

since in this case it fits winters formula pretty well then there’s no

additional respiratory component and what we’ve done is we’ve diagnosed

what’s happened an anion gap metabolic acidosis and a metabolic alkalosis okay

next question pH is equal to seven point two five $27.99

twelve chem-7 sodium 140 over 4.0 chloride is 118 and the bicarb is 12

first step calculate the anion gap 118 plus 12 is equal to 130 130 from 140 is

equal to 10 that means there’s no anti get metabolic acidosis

step number 2 go ahead and look at the pH and the pco2 are they going in the

same direction or in opposite directions in fact they’re going in the same

direction and they’re both going down therefore it’s a metabolic process and

it’s a metabolic acidosis because the pH is low therefore there must be something

pushing it down so it’s a metabolic acidosis the question is is there an

additional respiratory component and for that again we need to look at our

winters formula and that simply states that the drop in the pco2 and the bicarb

must be very similar again so if we have a drop in the hco3 minus and the pco2

that’s a drop of 1 to 1 let’s see if that occurred here so how much of a drop

in bicarb did we have again 24 is the normal number and it dropped from 24

down to 12 so therefore we had a drop in 12 points here we went from 40 down to

27 that’s a drop of about 13 again winters formula for metabolic acidosis

predicts that the pco2 went down exactly as it should have to compensate and

therefore there is no other respiratory component remember if the pco2 had gone

down even more than what was predicted by winters formula that would be an

additional respiratory alkalosis if the pco2 went down but went down by

less than predicted so let’s say it only went down by 5 points instead of 13

then that would be a respiratory acidosis in addition to the metabolic

acidosis next question pH is equal to seven point five zero 4890 bicarb 38

chem seven sodium is equal to 135 by car sorry P or potassium is three point six

chloride is 85 and as we mentioned bicarb is 38 first step measure anion

gap 85 plus 38 it’s 123 123 from 135 is 12 so the anion gap is equal to 12 the

Delta gap zero we do not have an anion gap metabolic acidosis step number two

look at the pH and the pco2 and see what the direction is here we have a pH going

up here we have a pco2 going up so it must be a metabolic problem and since

they’re both going up it must be in alkalosis question let’s do winters

formula again for every increase in the hco3 and an increase in the pco2 there’s

a two to one ratio in a metabolic alkalosis let’s see if that holds up

here how much that our bicarb go up by 24 is the normal number therefore it

went up by 14 points how much did our co2 go up by it went up

by 8 points is that ratio pretty consistent I would say so remember now

if the pco2 went up by more than 8 points then I would say there is a

concomitant respiratory s dosis if it went up by less than 8

points then I would say there’s a concomitant respiratory alkalosis but in

this case it looks like it’s about the same therefore we can say the secure

metabolic alkalosis okay next question pH is equal to seven point one five

forty 55 and a bicarb of 15 here we have our chem seven sodium is 140 potassium

4.0 chloride 98 bicarb is 15 first step calculate anion gap 98 + 15 is 113 113

240 anion gap is 27 that’s elevated okay so the Delta gap must be 27 minus 12

which is 15 we know right off the bat that we have an anion gap metabolic

acidosis okay so mud piles again mu dpi le s must be one of those and what do we

know we know that there are 15 units of the conjugate base or negative charge

hanging around that protons were released those protons were bound to

bicarbonate which we lost we lost that bicarbonate and so if we could just wave

our magic wand and say if we were to eliminate this and I get metabolic

acidosis what would our bicarb e and we simply

add this anion gap to our current bicarb level and we get 30 that’s what would it

be and if we saw a bicarb level of 30 we would say that means there must be a metabolic alkalosis occurring at the same time so we have

two different processes occurring at the same time so let’s look at our pH and

our pco2 okay remember we do that next pH pco2 obviously we’re dealing with a

metabolic acidosis so it’s going to be low and we look at our pH the question

now is since we have a metabolic acidosis and a metabolic alkalosis the

question is which one is stronger we need to know which one is stronger

because we need to know which winter’s formula to use do we use the metabolic

acidosis winters formula or do we use the metabolic alkalosis winters formula

and we see here that the metabolic acidosis must be the stronger of the two

so we’ll use the metabolic acidosis winters formula which states that the

drop in hco3 and the drop in p co 2 must be equal to 1 over 1 so let’s take a

look at that how much did our bicarb drop our bicarb dropped by 24 to 15

that’s 9 points okay how much did our pco2 drop by however our pco2 did not

drop at all it’s still at 40 how much should I have dropped it should have

dropped by and at 9 points right and the reason why is because winters formula

would predicts that if this were metabolic acidosis that were occurring

the bicarb drop of 9 should mean the pco2 drop should be 9 but it didn’t drop

low enough so if the pco2 did not drop low enough there must be a respiratory

acidosis because the pco2 did not drop enough so what we actually have here is

we have an anion gap metabolic acidosis we have a metabolic alkalosis and we

have a respiratory acidosis so we have a triple acid-base disorder that we could

figure out just based on the blood gas and also the chem 7 why don’t you join

me for part eight for a couple more questions Thanks

Very clear presentation….

thank you dr… it really helps me a lot! everything well explained.

Thanks for explaining. Was a little hard to understand for me at first, since we get the abg listed with different units here (kiloPascale and mmol/L) and also we get the base excess listed, which I guess is equivalent to the anion gap. .

Sorry bout that!. Actually the base excess is not the anion gap but is related to the amount of HO3 in the serum. (i.e. 0 means normal).

Yeah you're right, I went on to study it some more and realised you use the base excess (normal range -2 to +2) to determine wether there is a metabolic component to the pH, ie. renal compensation or metabolic alkalosis/acidosis through HCO3.

By the way I had my exam in acute medicine yesterday and was presented with 5 different abg's and everything went smooth. Got a B, I didn't get an A because I missed something on an X-ray hehe. So thanks again for the videos, I appreciate them. 🙂

Great! That's what this is all about – making the medical world make sense one topic at a time.

Thanks Dr. Roger Seheult! very well explained and I loved the fact that you added cases at the end. Thanks.

Man, this is so amazing. I did not truly understand the utility of delta gap and Winter's rules before this. Amazing.

I've been using the formula pCO2 = (1.5 x HCO3) + 8 for Winter's formula to find the expected pCO2 b/c I can calculate this faster than comparing the ratio of the delta HCO3 and delta pCO2. Does this work in all cases (never breaks down)?

Thank you very much.

12:28 what is the difference here between using the formula pCO2 = 1.5 x HCO3 + 8 and doing your method? I am curious because it seems the formula above suggests there would be a concomitant resp alkalosis with the met alkalosis, but that is not the conclusion you reached? So are both answers possibly correct? (as your fraction was also not as close as usual..)

Final example: will we ever need to differentiate between acute and chronic if the resp disorder is the 2nd concomitant problem?

there are several way of doing it. Another way is to simply at 15 to the bicarb and see what the CO2 is. if the actual co2 is higher then (bicarb + 15) you have a resp acidosis, if the actual co2 is lower then (bicarb + 15) you have a resp alkalosis. – works most of the time.

Sir, we do not have chloride ion conc. In our abg report , we have base excess how to calculate anion gap

Thank you very much

Hi, could you explain how you were able to tell in the first example that the additional bicarb was due to metabolic acidosis and not renal compensation?

This was the hard part – to understand the additional respiratory process that goes on with the metabolic process. Thank you for explaining it so well that anybody can understand. I cannot thank you enough for this lecture. Thank you.

Hi,Thanks for clear explanation and principle to use.

mecram for president of WHO

actually no

he would be too busy and neglect us and wouldnt make vids anymore 🙁

For the first example in this video, why does the Winturn's formula hold for AG Met Acidosis? Shouldn't the pC02 be higher since it has to compensate for Met Alkalosis as well?

Would it be correct ( or more appropriate ) to say in the first example that you have a AG metabolic AcidEMIA and a metabolic AlkalOSIS?

How did you determine in 16.28 that there is a respiratory acidosis when the rule for that is 1/3 or 1/2 when we have 9/0 ?

You are awesome, you should consider partnering with a rph who is just as knowledgeable in their field and understands the needs for naplex. This way we get both the med side and in depth pharm side. Although you do provide some info its not as in depth as we need.

adjusted anion gap = anion gap + (2.5x[4-serum albumin]

@7:34 – At what point would this shortcut break down? In this case, we assumed that 12/13 is close enough to 1/1, but exactly where can we draw that line? 12/14 is pretty close too but as we get further and further away, 12/15, 12/16, 12/17, where can we say that we are beginning to break away from a pure 1/1 ratio? In the Winter's formula, 1.5[HCO3]+8, there is a component of +/- 2 to account for this range. I like the method that you use but I need to be convinced that it won't miss any respiratory acid/base disturbances just because I assumed that the ratios were "close enough" to 1/1.

This video series has helped me out beyond words. Thank you so much Dr. Seheult!

Respiratory Therapy student here, this is helpful for my ABG quiz today. Thanks so much!

thanks alot

Damn. I finally understand this crap. Its still complicated but systematic approach helps to organize thoughts when solving these numbers. Thank you soooo much. My next issue is ECG. Will definitely buy the course. This guy kicks ass!!!

Finally I get it! thanks!

Acid base disorder very clear now many thanks to u. One more lecture to go!

how can we determine whether there is a concomitant metabolic alkalosis in non anion gap metabolic acidosis or not?

Hi

Thanks for your great lectures. Unfortunately the 8'th video is not available. I wonder why it's shown as a private video?

hi there thanks aot.. i have a patient of mine can help me ot for this confused with winters formula…

6.98/64.5/243/14.4 chem 7: 132/3.4/98/14.4

hope u can help

thanks again

What happened to the 8th video?

Where is the eighth Video…….??????????

I couldn't find the 8th part . could you plz share it with me?

Dear sir, Thank you and your team very much for all sharing these medical lectures.

I could not find part 8 ! How could i have it please?

This is the most helpful video about ABG I've ever watched. Though I think the 3rd example was wrong in application of Winters formula. Maybe a review would do wonders. Thanks anyway.