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Compensatory responses for acid-base disorders

Introduction

Overview

Overview

Compensatory changes for acid-base disorders include renal compensation and respiratory compensation.

Adequacy of compensatory responses for acid-base disorders

Adequacy of compensatory responses for acid-base disorders

Compensatory responses are not potent enough to correct the acid-base derangement but only to blunt the changes in pH resulted from the primary deficits. Ranges and limits of appropriate compensations are given as follows:[1][2][3]

Primary Deficit Expected Ranges of Compensation Limits of Compensation
Respiratory acidosis Acute: Δ[HCO3–] = + 0.1 mEq/L x ΔPCO2 [HCO3–] = 38 mEq/L
Chronic: Δ[HCO3–] = + 0.25 to 0.5 mEq/L x ΔPCO2 [HCO3–] = 45 mEq/L
Respiratory alkalosis Acute: Δ[HCO3–] = – 0.25 mEq/L x ΔPCO2 [HCO3–] = 18 mEq/L
Chronic: Δ[HCO3–] = – 0.4 to 0.5 mEq/L x ΔPCO2 [HCO3–] = 15 mEq/L
Metabolic acidosis PCO2 = 1.5 x [HCO3–] + 8 ± 2 (Winters’ formula)[4]
PCO2 = 15 + [HCO3–]
PCO2 = last 2 digits of pH		 PCO2 = 15 mm Hg
Metabolic alkalosis PCO2 = 0.7 x [HCO3–] + 21 ± 2
PCO2 = 15 + [HCO3–]
PCO2 = 0.6 x [HCO3–]		 PCO2 = 55 mm Hg
References

References

  1. ↑ Brenner, Barry M.; L. Lee Hamm; Thomas D. Dubose (2002). Acid-base and electrolyte disorders: a companion to Brenner & Rector’s The kidney. Philadelphia: Saunders. ISBN 0-7216-8956-6.
  2. ↑ DeFronzo, Ralph A.; Arieff, Allen I. (1995). Fluid, electrolyte, and acid-base disorders. Edinburgh: Churchill Livingstone. ISBN 0-443-08774-1.
  3. ↑ Rector, Floyd C.; Brenner, Barry M. (2008). Brenner & Rector’s the kidney. Saunders Elsevier. ISBN 1-4160-3105-7.
  4. ↑ 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)

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rim Halaby, M.D. [2]