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Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.

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Winters' formula

Introduction

Overview

Overview

Winters’ formula is a formula to assess the adequacy of respiratory compensation in the presence of a primary metabolic acidosis.

Historical Perspective

Historical Perspective

Winters’ formula, named after Robert W. Winters,[1][2] is a formula used to evaluate respiratory compensation when analyzing acid-base disorders and a metabolic acidosis is present.[3][4]

Winters’ formula

Winters’ formula

Winters’ formula can be given as

PCO2 = 1.5 x [HCO3–] + 8 ± 2

where HCO3– is given in units of mEq/L and PCO2 will be in units of mm Hg.

Interpretation

Interpretation

Winters’ formula gives an expected value for the patient’s PCO2; the patient’s measured PCO2 is then compared to this.

  • If the two values correspond, respiratory compensation is considered to be adequate.
  • If the measured PCO2 is higher than the calculated value, there is also a primary respiratory acidosis.
  • If the measured PCO2 is lower than the calculated value, there is also a primary respiratory alkalosis.
References

References

  1. ↑ Albert MS, Dell RB, Winters RW (1967). “Quantitative displacement of acid-base equilibrium in metabolic acidosis”. Annals of Internal Medicine. 66 (2): 312–22. PMID 6016545. Unknown parameter |month= ignored (help)
  2. ↑ Asch MJ, Dell RB, Williams GS, Cohen M, Winters RW (1969). “Time course for development of respiratory compensation in metabolic acidosis”. The Journal of Laboratory and Clinical Medicine. 73 (4): 610–5. PMID 5775132. Unknown parameter |month= ignored (help)
  3. ↑ “Case 1: Acid Base Tutorial, University of Connecticut Health Center”.
  4. ↑ “Acid-Base Disorders: Acid-Base Regulation and Disorders: Merck Manual Professional”.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]