learning ABG's

how our instructor taught us to determine if it was respiratory or metabolic:

if the ph goes down the paco2 goes up.

if the ph goes up the paco2 goes down.

like a see-saw its respiratory.

if the ph goes down and the hco3 goes down.

if the ph goes up and the hco3 goes up.

like a elevator its metabolic.

that was hard to put into words but i hoped it helped. otherwise you just have to learn the normals, sorry i don't have an easy way to remember them. just when i get to the test i write them down quickly first thing so i don't confuse myself later on.

ROME

Respiratory

Opposite

Metabolic

Equal

Example:

Normal Values:

pH 7.35-7.45 PaCO2 35-45 mm Hg PaO2 80-95 mm Hg HCO3 22-26 mEq/L

Lets say pH is 7.50 CO2 32 CO3 24

THE PH is elevated and Alkaline

THE CO2 is decreased

THE CO3 is normal

So the pH and CO2 are going in opposite directions which = Respiratory Opposite so this would be Respiratory alkalosis

Now lets say the pH was 7.32 (decreased and acidic) and the CO2 is 33 (decreased) since there both going in the same direction (decreasing) = Metabolic Equal and you would have Metabolic Acidosis

So basically take the Ph and determine if its acidic or alkaline then take the abnormal CO2 or CO3 value and determine which direction they are going (elevated or decreased) and apply ROME.

Good luck, hope this is not confusing.

how our instructor taught us to determine if it was respiratory or metabolic:

if the ph goes down the paco2 goes up.

if the ph goes up the paco2 goes down.

like a see-saw its respiratory.

if the ph goes down and the hco3 goes down.

if the ph goes up and the hco3 goes up.

like a elevator its metabolic.

that was hard to put into words but i hoped it helped. otherwise you just have to learn the normals, sorry i don't have an easy way to remember them. just when i get to the test i write them down quickly first thing so i don't confuse myself later on.

our instructor gave us the term metro (like the train) to remember which goes together and which does not. "metabolic equals together respiratory opposite" like the see-saw or the elevator.

thanks guys understnding it better, what about compensation, full/partial/none? how would you determine??

If there is full compensation, the pH will be normal. Example:

pH 7.35 (low side, but still within normal limits)

CO2 52 (high-acid)

HCO3 30 (high-alkaline)

The above would be compensated respiratory acidosis. The bicarbonate is elevated as it is compensating for the low pH, which is now WNL.

Partially compensated respiratory acidosis:

pH 7.32 (still acidic)

CO2 52 (high-acidic)

HCO3 30 (high-alkaline)

Uncompensated metabolic alkalosis:

pH 7.55 (alkaline)

CO2 37 (normal)

HCO3 35 (high-alkaline)

In this one the CO2 is normal, it has not elevated in an effort to bring the pH down.

Partially compensated metabolic alkalosis:

pH 7.5 (alkaline)

CO2 60 (high-acid)

HCO3 35 (high-alkaline)

In this one the pH is still alkaline, the bicarb is high, yet the CO2 is now elevated, too, in an effort to restore the pH, though it has not yet succeeded.

I hope this helps.

This website is a lifesaver for a nursing student http://danibanani.wordpress.com/ on the right side there is a column for ABG's with practice tests and tutorials, it really helped me.

google land of ABG's. It's the best thing ever for ABG interpretation. I didn't get it until after I was told about this by my nursing instructor. And to think I was a straight A student!