Help with blood gases

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Specializes in Inpatient Acute Rehab.

Can anyone help me understand how to tell the difference between metabolic and respiratory in the blood gases???

I can tell if a situation is acidosis or alkalosis, and if it compensated or uncompensated. BUT, I have a hard time telling whether the situation would be metabolic or respiratory. PLEASE HELP!!!

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This may sound really confusing so i will do a example below but if you have a Ph that is acidotic and a HCO3 that is acidotic and a PCO2 that is alkaline. (which ever one is with the PH is the indicator. IN this case the HCO3 is the same as the PH (acidotic) that means that it is Metabolic Acidosis. If the HCO3 were alkaline and the PH and PCO2 were both acidotic then then it would be respiratory Acidosis. IF the PCO2 and the PH were both alkalotic then it would be Respiratory alkalosis and if the PH and the HCO3 are both alkalotic then it would be metabolic alkalosis.

Do a tic tac toe method

Acid Neutral Alkaline

PH

HCO3

PCO2 This one is Respiratory

acidosis with partial

compensation

Acid Neutral Alkaline

PH Metabolic Acidosis

HCO3 uncompensated because the

PCO2 PCO2 is neutral not

alkaline

This is just a few examples. If you need more help let me know.

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It doesnt look right when it shows up in the posting so if you need a new example let me know and i can take a digital picture of an example on paper.

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I learned the "ROME" method, and it seems to work...

R = respiratory

O = opposite

M = metabolic

E = equal

"Respiratory opposite, metabolic equal". If the pH is low and the PCO2 is high, it is respiratory acidosis (PCO2 and pH moving in opposite directions from normal value). If the pH is low and the HCO3 is low, it is metabolic acidosis. If the pH is high and the PCO2 is low, it is respiratory alkalosis. If the pH is low and the HCO3 low, it is metabolic alkalosis.

Hope that makes sense!

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Specializes in Inpatient Acute Rehab.

Thank you both!!!

The ROME method is easier for me. However, what if the pH is in normal range? I know that means the condition is compensated, but what if the pCO2 and the HCO3 are both abnormal, but the pH is normal? How do you tell which one it is, metabolic or respiratory??

This is the hardest thing I have had to learn in school!!!!

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I also found ABG's to be the most difficult thing I learned in nursing school!

If the pH is normal, you can still use the ROME method to figure out the problem. For example, if the pH is on the lower end of normal range and the PCO2 is high, it is still respiratory acidosis. But in this situation the HCO3 is probably getting higher as well, as the body is correcting the respiratory problem by excreting more HCO3. The pH is starting to return to normal because of this compensation. So it is compensated respiratory acidosis. If you go back and do ROME you will see that your pH and respiratory component arrows are going in opposite directions, telling you that it is a respiratory problem (Respiratory Opposite) and your pH and metabolic component arrows are also going in opposite directions to compensate. Since a metabolic problem would result in the HCO3 and pH going in the same direction (Metabolic Equal) you can see that it is a respiratory problem with metabolic compensation. It really helps me to put the arrows next to my actual results.

Hope this helps!

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Specializes in Inpatient Acute Rehab.

:kiss :kiss :kiss

THANK YOU curly nurse!!! That helped so much!!!

I did 10 problems with your method and got all 10 right!!!

AWESOME!!!

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