What's your answer??

My guess is compensated resp acidosis. The pH is on the acidic side of 7.4. I was taught that is how you can tell which side it comes from by using that rule. You gain base to make the pH less acidic.

I hope that's right. Maybe I should go get my notes out.

On the 1st one I would say Compensated Respiratory Acidosis because the pH is normal but closer towards the acid (7.4 as midpoint) with the CO2 (acid) high. The elevated HCO3 (alkaline) is in response to the high CO2, in order to bring up the pH. CO2 indicates respiratory, HCO3 indicates metabolic causes. It is also possible to have a mixed disturbance, with a definitive cause.

On the second one; what would you say the pH is? You initially look at that to see where the shift is from midline on 7.4-that will tell you if it is had an acidotic or alkalotic origin. Let's say it stayed 7.36, so it's origin remains acidotic; and, the acidotic number would be the metobolic HCO3 (19)---Compensated Metabolic Acidosis would be the answer. The breathing of the patient just compensated for the metabolic acidosis to bring the pH to normal (that's where the alkaline CO2 came from).

Now, if you get a pH of 7.4 with, let's say, the both the CO2 & HCO3 high, CO2 indicating acidosis and HCO3 indicating alkalosis---you really can't tell it's origin. The full clinical picture of the patient would be needed because the metabolic compensatory mechanism would take days to develop, where the respiratory component is almost immediately seen. This time delay for a metabolic compensatory response would be the only thing that could clue you in to a respiratory origin. I remember some instructors trying to trick students with this one.

Hope this helps and I haven't confused you.

Remember ROME -- Respiratory Opposite Metabolic Equal

Meaning, if the pH and CO2 are going in opposite directions and extend the normal value range, you have respiratory alkalosis/acidosis.

If the pH and HCO3 are going in the same direction and extend the normal value range, you have metabolis alkalosis/acidosis.

After you figured out whether it is respiratory or metabolic, look at the other factor and if it is not within the normal value range, you will have compensation.

That is a general rule, although with every rule there are exceptions.

Forgot to include in my previous posting.

The ABG examples you are providing are referred to as "mixed disorders" or "complex acid-base". I am suprised your school makes you learn mixed disorders and complex acid-base.

For example, your first one states: pH 7.36, CO2 50, HCO3 35. It would be: Chronic (compensated) primary respiratory acidosis, with metabolic alkalosis.