Первинні зміни та компенсаторні механізми при простих порушеннях кислотно-основної рівноваги

Primary Disturbance

pH

Bicarbonate (HCO3)

Pco2

Expected Compensation

Metabolic acidosis

< 7.35

Primary decrease

Compensatory decrease

1.2 mm Hg decrease in Pco2 for every 1 mEq/L (1 mmol/L) decrease in HCO3

  or*

Pco2= (1.5 × HCO3) + 8 (± 2)

  or

Pco2= HCO3+ 15

  or

Pco2= last 2 digits of pH ×100

Metabolic alkalosis

> 7.45

Primary increase

Compensatory increase

0.6–0.75 mm Hg increase in Pco2 for every 1 mEq/L (1 mmol/L) increase in HCO3 (Pco2 should not rise above 55 mm Hg in compensation)

Respiratory acidosis

< 7.35

Compensatory increase

Primary increase

Acute: 1–2 mEq/L (1–2 mmol/L) increase in HCO3 for every 10-mm Hg increase in Pco2

Chronic: 3–4 mEq/L (3–4 mmol/L) increase in HCO3 for every 10-mm Hg increase in Pco2

Respiratory alkalosis

> 7.45

Compensatory decrease

Primary decrease

Acute: 1–2 mEq/L (1–2 mmol/L) decrease in HCO3 for every 10-mm Hg decrease in Pco2

Chronic: 4–5 mEq/L (4–5 mmol/L) decrease in HCO3 for every 10-mm Hg decrease in Pco2

* Imprecise but convenient rules of thumb.

HCO3- = bicarbonate; Pco2 = carbon dioxide partial pressure.