Flashcards in pH Disorders Deck (19)
What is the difference between Acidemia vs. Acidosis?
acidemia is the pH's change away from the reference range (so just a description of the lab)
acidosis refers to the abnormal condition or process that contributes to the pH's change
(same difference for alkalemia and alkalois)
What is the normal pH range?
What is the normal pCO2 range?
38-42 mm hg
What is the normal HCO3 range?
What are the implications of the henderson-Hasselbach equation?
it's the HCO3/H2CO3 buffer system
Basically, if pCO2 goes up, then pH goes down
If HCO3 goes up, then pH goes up
CO2 is the acid and HCO3 is the base
What are Dr. Li's steps for working through acid base problems?
identify all the abnormalities (pH/CO2/bicarb)
acidosis vs alkalosis
metabolic or respiratory
acute or chronic
calculate anion gap
calculate the expected pCO2 range
How do you calculate the anion gap?
Na - (Cl + HCO3)
What's the normal range for anion gap?
7-16 (12 typically used)
WHat are the normal "unmeasured" anions in the gap?
If the anion gap is over 20, but the pH and bicarb is normal, does the patient have an acidosis?
YES - anion gap over 20 defines metabolic acidosis regardless of what the pH or bicarb are doing, which is why you always need to calculate it
just means there is a mixed process going on
Why do you need to calculate the expected pCO2 range?
it determines whether respiratory compensation is adequate or under or over-compensated
How do you calculate the expected pCO2 range?
1.5 x (measured HCO3) + 8 +/- 3
If the pCO2 is above the expected range, what is the secondary process?
respiratory acidosis even if the pCO2 is below 40
If the pCO2 is less than the expected range, what's oging on?
they're not compensating appropriately, so there is a concomitant respiratory alkalosis
If there is an anion gap, what do you need to calcualate next? Why?
the excess anion gap (or delta gap)
It allows you to determine the "corrected" bicarbonate to see whether there are any other metabolic disturbances
How do you calculate the excess anion gap?
Calculated AG - 12
How do you calculate the corrected bicarbonate?
Corrected bicarb = measured bicarb + excess anion gap
A corrected bicarb over what will reveal an underlying primary metabolic alkalosis?