Metabolic acidosis: Difference between revisions
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{{Non anion gap acidosis}} | {{Non anion gap acidosis}} | ||
== | ==Evaluation== | ||
;Osm gap = measured osm - calculated osm (normal 10-15) | ;Osm gap = measured osm - calculated osm (normal 10-15) | ||
;Calculated Osm = 2(Na)+(glucose/18)+(BUN/2.8)+(BAL/5) | ;Calculated Osm = 2(Na)+(glucose/18)+(BUN/2.8)+(BAL/5) | ||
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==References== | ==References== | ||
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[[Category:FEN]] | [[Category:FEN]] | ||
[[Category:Toxicology]] | [[Category:Toxicology]] | ||
Latest revision as of 15:12, 22 July 2017
Clinical Features
- Compensatory respiratory tachypnea
Differential Diagnosis
Anion gap metabolic acidosis
- Lactic acidosis
- Sepsis, shock, liver disease, CO, CN, metformin, methemoglobin
- Short bowel syndrome
- Propylene glycol infusions for lorazepam and phenobarbital
- Renal failure
- Ketoacidosis
- Ingestions
- Acetaminophen toxicity
- Aspirin toxicity
- Increased osm gap
- Normal osm gap
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)
- CKD
- Intestinal, pancreatic, biliary fistula
- Hyperchloremic IVF infusions
- Hyperalimentation
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