ABG help

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Specializes in Pediatrics.

We have a test tomorrow on ABG's. Just simple stuff. I was practicing them from http://realnurseed.com/abgm2.htm. But for some reason I missed two. I am trying to figure them out but have no idea why they are what they are.

The first one is:

pH 7.43 [Which is normal]

PaCO2 32 [Low]

HCO3 21 [Low]

So would it not be Compensated Metabolic Alkalosis?

Rationale for my answer: The pH is normal so that's not even the question; The PaCO2 is low which is respiratory; HCO3 is low as well which is Metabolic; That the pH is closer to the Alkaline side; So would it not be Metabolic?

I don't know; someone please HELP! :banghead:

Thanks SO much! :bugeyes:

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Ok. I know a few ways to figure ABG's, but the easiest to explain is the old ROME- respiratory opposite metabolic equal!

If it is Respiratory the PH and the CO2 will be going in opposite directions- One high the other low.

If it is metabolic the HCO3 and PH will both be high or both be low!!

You questions: The PH is in the normal range because it has been compensated...

THe PH is HIGH normal the CO2 is low and the HCO3 is low..

By the ROME formula... the respiratory and the PH are going in the opposite dirrections.. that makes this Compensated (cause the PH is now normal ((becaue the kidneys decreased the production of bicarb)))respiratoy alkalosis.

Hope this makes SOME sense and helped a little!!

JG

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Specializes in med/surg, telemetry, IV therapy, mgmt.

It's compensated respiratory alkalosis. When you analyze you always consider in this order:

  1. pH
  2. CO2 (the respiratory component)
  3. HCO3 (the metabolic component)

pH was normal, so you move on. Since both the CO2 and HCO3 were whacked, you consider the respiratory component first. Then, look back at the pH to see what happened. The pH is normal so compensation is occurring, but since it is .02 below 7.45 of normal means it was slightly alkalotic to begin with, thus, there was respiratory alkalosis. It is only metabolic alkalosis if the pH is in the alkalosis range and that clearly has not happened here.

What was the second one you missed?

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Specializes in TCU.

Punky

Please try this link, I think the 3rd post down has a great explanation.

https://allnurses.com/forums/f205/about-acidosis-alkalosis-ctxt-93156.html

Cheers!

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Specializes in Pediatrics.

Okay that makes sense.

The second on I missed was:

pH: 7.42 [N]

CO2: 32 [L]

HCO3: 27 [H]

I put that it was Compensated Metabolic Alkalosis.

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Specializes in med/surg, telemetry, IV therapy, mgmt.

the rome mnemonic only works when the ph is whacked. when the ph is within normal limits you have a compensated situation and must analyze in the order of which gas is out of whack (respiratory trumps metabolic) and which way the ph has been tweaked (acid or base)

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Specializes in med/surg, telemetry, IV therapy, mgmt.
Okay that makes sense.

The second on I missed was:

pH: 7.42 [N]

CO2: 32 [L]

HCO3: 27 [H]

I put that it was Compensated Metabolic Alkalosis.

It is also compensated respiratory alkalosis. Analysis:

  1. pH - 7.42 (normal)
  2. CO2 - 32 (low)
    • so, this is a compensated respiratory something. Now, go back and look at the pH and see which way it is tweaking

[*]HCO3 (high)

  • the high HCO3 indicates the body is making a lot of a base (the HCO3) in order to lower the pH, so the pH had to be much higher than 7.42 at some point. A high pH would have been alkalosis that is now compensated.

[*]Answer: Compensated respiratory alkalosis

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Specializes in Pediatrics.

Thank you so much! That makes it alot clearer now! :smackingf

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Specializes in med/surg, telemetry, IV therapy, mgmt.

did you see the abg links? https://allnurses.com/forums/2488838-post46.html i thought there was something on there about analyzing abgs. use rome if the ph is abnormal. do the 1,2,3 thing if the ph is in a normal range because they are compensated.

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