ABG question

chihuahuaman · Oct 7, 2011

There's a whole thread right there...

https://allnurses.com/nursing-student-assistance/easy-way-remember-144947.html

And if you type "ABG" into the search thingy up at the top of the page you will find loads of links to discussions.

Lbarrien · Oct 7, 2011

I saw that but I'm confused about these lab values. The HCO3 is suppose to be decreased with the pH in order to be metabolic acidosis, but its increased and the PaCO2 is normal so there it cant be respiratory alkalosis, respiratory acidosis, metabolic alkalosis, or even metabolic acidosis. There is no answer and someone told me it means its compensating but idk what they mean and if it is compensating (whatever that means) what is it called metabolic or respiratory?? I'm lost.

stillStriving · Oct 8, 2011

It's metabolic acidosis..

Lbarrien · Oct 8, 2011

Compensating? If so what does that mean?

loveslife · Oct 8, 2011

first thing to look at is the pH. normal pH is 7.35 to 7.45. if it is than its alkalosis. Compensated means that the pH has returned to the normal range. the pH is 7.33 so its acidosis

Next look at PaCO2 normal is 35-45. If this level is off than the condition is respiratory. CO2 is an acid so if there is more ( >45) it is acidosis. But if there is

The HCO3 is next. If this level is off than it is metabolic Normal is 22-26. Bicarb is a base so if there is more of this(>26) than it is alkalosis and less than(

PaO2 will not help you determine acid base balance. PaO2 normal is 80-100. This assesses the % of oxygen bound to hemoglobin and helps you to determine the pts perfusion(gas exchange)

Hope this helps

dudette10, MSN, RN · Oct 8, 2011

I think it's partially compensated respiratory acidosis. Gas exchange is affected, as shown by the Dx and low O2.

The thing that throws me off is the normal range of CO2, but the baby might be breathing rapidly and shallowly in order to blow off the CO2 that caused the acidotic condition. The bicarb is elevated to compensate for the lower pH.

I'm sticking with PCRA.

loveslife · Oct 8, 2011

Another thing to help you is to remember is that Metabolic conditions the arrows follow eachother. pH is low in metabolic acidosis( down arrow) and HCO3 is low( down Arrow) down down OR if pH is high in alkalosis(up arrow) HCO3 is high(up arrow) up up

This is true because HCO3 is a base. Bases raise the pH

Respiratory conditions the arrows are opposite. In respiratory acidosis the pH is low(down arrow) and the PaCO2 is high (up arrow) In respiratory alkalosis the pH is high(up arrow) and the PaCO2 is low(down Arrow) up down or down up

This is true because CO2 is an acid. Acids lower the pH.

belle005 · Oct 8, 2011

Hmm.... I'm no expert, but I'll try! It's not terribly clear because the pCO2 is normal. Any chance you wrote the values incorrectly? 7.33 is acidic. So the patient has acidosis. It's not fully compensated or the pH would be back within normal range. It is partially compensated though because the HCO3 is higher than normal range - indicating the kidneys are the compensation mechanism at work - which points to respiratory as the initial problem. I want to think it's respiratory acidosis because of the respiratory issues and the fact the kidneys are compensating by retaining HCO3.

Lbarrien · Oct 8, 2011

Thanks everyone that helped alot!! I now understand the concept and I truly appreciate everyone's help.

loveslife · Oct 8, 2011

"I think it's partially compensated respiratory acidosis. Gas exchange is affected, as shown by the Dx and low O2.
The thing that throws me off is the normal range of CO2, but the baby might be breathing rapidly and shallowly in order to blow off the CO2 that caused the acidotic condition. The bicarb is elevated to compensate for the lower pH."
Its not respiratory because the CO2 is normal. Think about the compensation the body does the lungs(quick) and the kidneys(slow) BOTH try to compensate but the lungs compensate first with breathing, which is the quickest way to compensate, then the kidneys. The breathing you are talking about would be true for acidosis as this compensatory mechanism is quick and happens first. Then the kidneys compensate and it is the reason for a high HCO3. The body is compensating by the kidneys retaining HCO3, a base, to counteract a low pH.
RSV is a virus that causes impaired gas exchange, yes, but the pt is 3 months old. Infants are at a very high risk for fluid loss and when the cannot get enough oxygen they cannot drink, as swallowing and eating require a pause in breathing. Thus, the pt would be severly dehydrated. Severe dehydration causes metabolic acidosis.

dudette10, MSN, RN · Oct 8, 2011

You're saying that it can't be respiratory because CO2 is normal, so it must be metabolic acidosis, although the bicarb value and diagnosis don't support metabolic acidosis. Then, in order to support your rationale for metabolic acidosis, you're throwing in reduced fluid intake and insensible losses to justify the idea of severe dehydration that can lead to it.

I don't agree with that line of thinking for a nursing school question (maybe not even in real life, but I have no experience with that right now). It's just too convoluted.

BOTH try to compensate but the lungs compensate first with breathing, which is the quickest way to compensate, then the kidneys. The breathing you are talking about would be true for acidosis as this compensatory mechanism is quick and happens first. Then the kidneys compensate and it is the reason for a high HCO3. The body is compensating by the kidneys retaining HCO3, a base, to counteract a low pH.

You had the answer right here, before you went into the dehydration thing. The breathing IS compensating by lowering the CO2 to normal, but the kidneys kicked in, too.