Metabolic acidosis: Difference between revisions

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== Differential Diagnosis==
== Differential Diagnosis==
=== Gap ===
{{Anion gap metabolic acidosis}}
*[[Lactic acidosis]]
**[[Sepsis]], [[shock]], liver disease, [[CO]], [[CN]], [[metformin]], [[methemoglobin]]
*[[Renal failure]]
**[[Uremia]]
*Ketoacidosis
**[[DKA]]
**[[Alcoholic Ketoacidosis]]
**[[Starvation ketoacidosis]]
*Ingestions
**Increased osm gap
***[[Methanol]], [[ethylene glycol]]
**Normal osm gap
***[[ASA]], [[iron]], [[INH]]


;Osm gap = measured osm - calculated osm (normal 10-15)
;Osm gap = measured osm - calculated osm (normal 10-15)

Revision as of 19:56, 11 June 2015

Background

  • 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

Differential Diagnosis

Anion gap metabolic acidosis

Osm gap = measured osm - calculated osm (normal 10-15)
Calculated Osm = 2(Na)+(glucose/18)+(BUN/2.8)+(BAL/5)

Non-gap

  • Hyperkalemia
    • Resolving DKA
    • Early uremic acidosis
    • Early obstructive uropathy
    • RTA Type IV
    • Hypoaldosteronism
    • K-sparing diuretics
  • Hypokalemia
    • RTA Type I
    • RTA Type II
    • Acetazolamide
    • Acute diarrhea
      • (May be assoc with gap if hypoperfusion -> lactic acidosis)

Treatment

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

See Also

Acid-Base

Source

Tintinalli