Winter’s Formula Calculation: Expected pCO2 = 1.5 * HCO3- + 8 +/- 2
When to use Winter’s Formula
Winter formula is used during times of metabolic acidosis, metabolic acidosis is when both pH < 7.35 and HCO3- < 22 on an arterial blood gas.
What is the purpose of the Winters formula
Is the respiratory system properly compensating for the metabolic acidosis.
| HCO3− mEq/L | |
| pCO2 in mmHg |
If measured and calculated values correspond, respiratory compensation is considered to be adequate. How ever if something else is going on there is improper compensation.
- PCO2 is greater than the calculated value, there is also a primary respiratory acidosis.
- PCO2 is less than the calculated value, there is also a primary respiratory alkalosis.
