Winters' formula

Winters' formula, named after Dr. R.W. Winters, is a formula used to evaluate respiratory compensation when analyzing acid-base disorders and a metabolic acidosis is present. It can be given as

${\displaystyle P_{CO_{2}}=(1.5\times HCO_{\operatorname {sgn} })+8\pm 2}$,

where HCO₃⁻ is given in units of mEq/L and P_CO2 will be in units of mmHg.

Winters' formula gives an expected value for the patient's P_CO2; the patient's actual (measured) P_CO2 is then compared to this.
If the two values correspond, respiratory compensation is considered to be adequate.
If the measured P_CO2 is higher than the calculated value, there is also a primary respiratory acidosis.
If the measured P_CO2 is lower than the calculated value, there is also a primary respiratory alkalosis.