Winters' formula, named after Dr. R.W. Winters, is a formula used to evaluate

respiratory compensation Respiratory compensation is the modulation by the brainstem respiratory centers, which involves altering alveolar ventilation to try and bring the plasma pH back to its normal value (7.4) in order to keep the acid-base balance in the body. It ...

when analyzing acid-base disorders in the presence of

metabolic acidosis Metabolic acidosis is a serious electrolyte disorder characterized by an imbalance in the body's acid-base balance. Metabolic acidosis has three main root causes: increased acid production, loss of bicarbonate, and a reduced ability of the kidneys ...

. It can be given as:

P_ = (1.5 \times HCO_\sgn) + 8 \pm 2

, where ⁻ is given in

units Unit may refer to: Arts and entertainment * UNIT, a fictional military organization in the science fiction television series ''Doctor Who'' * Unit of action, a discrete piece of action (or beat) in a theatrical presentation Music * Unit (album), ...

mEq/L An equivalent (symbol: officially equiv; unofficially but often Eq) is the amount of a substance that reacts with (or is ''equivalent'' to) an arbitrary amount (typically one mole) of another substance in a given chemical reaction. It is an arc ...

and P will be in units of mmHg. Winters' formula gives an expected value for the patient's P; the patient's actual (measured) P is then compared to this.
If the two values correspond,

is considered to be adequate.
If the measured P is higher than the calculated value, there is also a primary

respiratory acidosis Respiratory acidosis is a state in which decreased ventilation (hypoventilation) increases the concentration of carbon dioxide in the blood and decreases the blood's pH (a condition generally called acidosis). Carbon dioxide is produced continu ...

.
If the measured P is lower than the calculated value, there is also a primary

respiratory alkalosis Respiratory alkalosis is a medical condition in which increased respiration elevates the blood pH beyond the normal range (7.35–7.45) with a concurrent reduction in arterial levels of carbon dioxide. This condition is one of the four primary dis ...

References

Respiratory therapy Mathematics in medicine {{Medicine-stub