ABG’s
Acid=lemon Juice acidic, PCO2
PCO2= respiratory
Base=soap=HCO3 alkaline
HCO3= metabolic
Normal values to memorize-
PH 7.35-7.45 7.40 is dead center normal
PCO2 35-45
HCO3 22-26
If the ph is lower then 7.35 it is ALWAYS an ACDIOSIS problem
If the ph is HIGHER then 7.45 then it is ALWAYS an ALKALINE problem
IF the ph is between 7.35-7.45 it is either a normal ABG, or it is fully compensated.
If fully compensated look to see on which side of 7.40 it lays, if lower then 7.40 its acidosis, if higher then it’s alkaline.
There are two primary ways to get an acidosis. The first is by adding acid to the equation (if you added acid to get the acidosis its known as a respiratory acidosis cause your increasing the PCO2. The second is by decreasing the amount of Base- this is known as a metabolic acidosis. You can also have an acidosis when both acids has been added and base has been removed, that’s when it’s known as a respiratory and metabolic acidosis.
Let’s review these concepts with examples
Ph PCO2 HCO3
7.20 44 18
Look at the pH first…. It is lower then 7.35 so it is an acidosis problem.
Next look at the PCO2, is it higher then normal value? No its not, so it’s not respiratory. Next look at the HCO3 is it lower then normal yes, so it’s a metabolic acidosis.
How did we know we were looking for a higher PCO2 or Lower HCO3, because the PH was low and thus we were looking for an acidosis?
Let’s do another problem
Ph PCO2 HCO3
7.32 48 24
LOOK at the ph first- is it higher or lower then the Norms? Its lower so we are looking for a what? An acidosis. Next look at the PCO2 is it higher then the norm? Yes so we have a respiratory acidosis, but don’t stop there look at the HCO3 too to make sure it’s not both a respiratory and metabolic disorder. Is 24 low for HCO3? No it’s normal. So this is a respiratory acidosis.
Lets do one more problem
Ph PCO2 HC03
7.18 68 18
Look at the ph first is it higher or lower then normal? Lower so it’s an acid problem.
Now look at the PCO2 is it higher then normal? Yes so that means it’s a respiratory problem, now look at the HCO3 is it lower then normal? Yes so it’s a metabolic problem
So what do you have? A respiratory and metabolic acidosis.
There are two primary ways to get an alkalosis The first is by adding base to the equation (if you added base to get the alkalosis its known as a metabolic alkalosis cause your increasing the HCO3. The second is by decreasing the amount of acid this is known as a respiratory alkalosis. You can also have an alkalosis when both base has been added and acid has been removed, that’s when it’s known as a respiratory and metabolic alkalosis.
Let’s review these concepts with examples
Ph PCO2 HCO3
7.48 30 26
Is the Ph normal? High? Or low? ….. High so its al alkaline problem.
Next look at the PCO2 is it low? Yes so we have respiratory problem, but don’t stop there, remember to look at the HCO3 is it high? No its not, its normal. So then we have a respiratory alkalosis
Lets do more!
Ph PCO2 HCO3
7.7 20 38
Is the ph normal? High ? or low? It is High so we are look for what caused it to be alkaline.
Look at the PCO2 is it low? Yes so we have a respiratory problem, Look at the HCO3 is it high? Yes so we have a metabolic problem
So our answer would be a respiratory and metabolic alkalosis.
Another problem
Ph PCO2 HCO3
7.34 48 24
Is the ph Normal? High or Low? Low so we are looking for an acidosis. Next look at the PCO2 is it high? Yes so we have a respiratory acidosis, now look at the HCO3 is it low? No it’s normal so we have a respiratory acidosis.
Now lets complicate the problem and deal with compensation. Compensation happens when we have either an Acidosis or Alkalosis and one system is causing the problem and the other system kicks in to try and reverse the problem.
Hint* if both the PCO2 and HCO3 is low you have compensation
If both the PCO2 and HCO3 are high you have compensation
How can you tell which you’re looking for the Acidosis or the Alkalosis?
By looking at the PH, although the Ph might be within the “normal” range it will usually fall on either side of 7.40. if it is lower it’s an acidosis problem. If it’s higher its alkalosis.
You can either have a partially compensated or fully compensated. It’s considered partially compensated any time the ph is not in the normal range but the other system has kicked in and helped out some. It is considered fully compensated as soon as the ph enters the “normal” range.
Lets apply this new information to some problems.
Ph PCO2 HCO3
7.28 22 10
look at the ph first? Is it normal? High? Or low? Low so we are looking for an acidosis. So if it’s an acidosis either the PCO2 will be high or the HCO3 will be low, or both.
Let’s start by looking at the PCO2? Is it normal? No its low…. But low PCO2 won’t give you an acidosis. So look at the HCO3 is it normal? No it’s low. Will a low HCO3 give you an acidosis? Yes
So you have a metabolic acidosis…. But we already said the PCO2 isn’t normal it’s also low so it’s helping to compensate. Is it fully compensated or partially? Partially because the ph is not in the normal range.
So what do you have? Metabolic acidosis with partial compensation.
Another problem
Ph PCO2 HCO3
7.39 64 32
look at the ph. Is it normal? High? Low? It is normal…..so do we have a normal ABG? No because the PCO2 and the HCO3 are not with in their normal range. So lets look at the PH again, its it on the high or low side of 7.40? low, so its an Acidosis problem. So lets look at the gasses again. Is the PCO2 causing an Acidosis? Yes because its high. So we have a respiratory acidosis. Now look at the HCO3 is it in the normal range? No its also high so its compensating.
So what do we have a respiratory acidosis with full compensation.
Why is it full because the ph in within the normal range.
Lets do more for pratice
Ph PCO2 HCO3
7.41 10 10
look at the ph frist. Is it normal? High or low? It is normal. So do we have a normal ABG? No because the PCO2 and the HCO3 are not within normal range.
So lets look at the ph again is it on the high or low side of 7.40? High so we have an alkaline problem. So lets look at the PCO2 now, would a PCO2 of 10 cause an alkalosis? Yes, now lets look at the HCO3 would a HCO3 of 10 cause a alkalosis no it would cause an acidosis. So what do we have?
We have a respiratory alkalosis with full compensation
Lets do one more
Ph PCO2 HCO3
7.38 38 24
look at the ph is it normal? Yes. So look at the gasses are they normal? Yes so what do you have ? a normal blood gas.