Summary Flashcards
Normal pH lab value:
7.38 - 7.44
Condition with pH < 7.38:
acidemia
Condition with pH > 7.44:
alkalemia
Normal PCO2 lab value:
35-45 (magic #40)
Normal HCO3- lab value:
21-30 (magic #24)
Normal anion gap value:
7-16 (magic #12)
Normal ∆-∆ value:
-5 to +5
Anion gap formula and when to use:
AG = [Na+] - ([Cl-] + [HCO3-])
Use: metabolic acidosis only.
∆-∆ formula and when to use:
∆-∆ = ∆AG - ∆[HCO3-]
Use: AG elevated metabolic acidosis only.
∆AG =
∆AG = measured AG - 12
use in ∆-∆ calculation
∆[HCO3-] =
∆[HCO3-] = 24 - measured [HCO3-]
use in ∆-∆ calculation
Winter’s formula and use:
PCO2 = 1.5[HCO3-] + 8 ± 2
- Use: metabolic acidosis only to determine whether or not PCO2 compensation has occurred. Should decrease in metabolic acidosis.
Formula that should be used to determine compensation status in the setting of metabolic acidosis:
Winter’s formula
PCO2 = 1.5[HCO3-] + 8 ± 2
Formula that should be used to determine compensation status in the setting of metabolic alkalosis:
PCO2 = 0.7[HCO3-] + 20 ± 2
- Use: calculate predicted PCO2. Should rise in metabolic alkalosis.
Compensation rules for respiratory acidosis (acute versus chronic):
- acute: up 1 [HCO3-] for every up 10 PCO2.
- chronic: up 4 [HCO3-] for every up 10 PCO2.