Metabolic acidosis

(Redirected from Metabolic Acidosis)

Clinical Features

  • Compensatory respiratory tachypnea

Differential Diagnosis

Anion gap metabolic acidosis

Non-gap

Evaluation

Osm gap = measured osm - calculated osm (normal 10-15)
Calculated Osm = 2(Na)+(glucose/18)+(BUN/2.8)+(BAL/5)
  • Primary acidosis if pH <7.38
  • HCO3 <24 = metabolic acidosis
  • Always determine if there is another acid/base process occurring
    • Primary respiratory acidosis if pCO2 > pCO2expected
    • Primary respiratory alkalosis if pCO2 < pCO2expected
      • use Winter's formula: PCO2 (expected) = (1.5 x [HCO3–] + 8) ± 2
      • In acute setting PCO2 should fall by 1 mmHg for every 1 mEq fall in HCO3
    • Concurrent metabolic alkalosis if delta-delta > 28
    • Delta-Delta = (AG - 12) + HCO3

Management

  • Treat source
  • Correct any respiratory acidosis
  • Bicarbonate
    • HCO3 dose in mEq = 0.5(wt in kg) x (24 - measured HCO3)
    • Each bicarb 0.5mEq/kg causes 1 meq/L rise in HCO3
    • Consider for:
      • Bicarb <4
      • pH <7.20 AND shock/myocardial irritability
      • Severe hyperchloremic acidemia
      • lower threshold with non-AG acidosis (greater HCO3 loss)
        • Lost bicarbonate would take days to replenish

See Also

References

Authors:

Ross Donaldson