Metabolic acidosis: Difference between revisions

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
- Uremia
Ketoacidosis
Ingestions
- Acetaminophen toxicity
- Aspirin toxicity
- Increased osm gap
  - Methanol
  - Ethylene glycol
- 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

References

Authors:

@@ Line 1: / Line 1: @@
-== Background ==
+==Clinical Features==
-*Always determine whether there is a primary respiratory acidosis as well
+*Compensatory respiratory tachypnea
-**PCO2 (expected) = (1.5 x [HCO3–] + 8) ± 2
-**In acute setting PCO2 should fall by 1 mmHg for every 1 mEq fall in HCO3
-== DDX ==
+==Differential Diagnosis==
+{{Anion gap metabolic acidosis}}
-=== Gap ===
+===Non-gap===
+{{Non anion gap acidosis}}
-#Lactic acidosis
+==Evaluation==
-##Sepsis, shock, liver dz, CO, CN, metformin, methemoglobin
+;Osm gap = measured osm - calculated osm (normal 10-15)
-#Renal failure
+;Calculated Osm = 2(Na)+(glucose/18)+(BUN/2.8)+(BAL/5)
-##Uremia
-#Ketoacidosis
-##DKA, AKA, starvation
-#Ingestions
-##Inc osm gap
-###Methanol, ethylene glycol
-##Nl osm gap
-###Salicylates
-=== Non-gap ===
+*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
-#Hyperkalemia
+==Management==
-##Resolving DKA
+*Treat source
-##Early uremic acidosis
+*Correct any [[respiratory acidosis]]
-##Early obstructive uropathy
+*[[Bicarbonate]]
-##RTA Type IV
+**HCO3 dose in mEq = 0.5(wt in kg) x (24 - measured HCO3)
-##Hypoaldo
+**Each bicarb 0.5mEq/kg causes 1 meq/L rise in HCO3
-##K-sparing diuretics
+**Consider for:
-#Hypokalemia
+***Bicarb <4
-##RTA Type I
+***pH <7.20 AND shock/myocardial irritability
-##RTA Type II
+***Severe hyperchloremic acidemia
-##Acetazolamide
+***lower threshold with non-AG acidosis (greater HCO3 loss)
-##Acute diarrhea
+****Lost bicarbonate would take days to replenish
-###(May be assoc with gap if hypoperfusion -> lactic acidosis)
-== Treatment ==
+==See Also==
-#Treat source
+*[[Acid-base disorders]]
-#Correct any respiratory acidosis
-#Each bicarb 0.5mEq/kg causes 1 meq/L rise in HCO3
-=== Bicarbonate Indications ===
-#Bicarb <4
-#pH <7.20 + shock/myocardial irritability
-#Severe hyperchloremic acidemia
-##Lost bicarbonate would take days to replenish
-== Source ==
-Tintinalli
+==References==
+<references/>
 [[Category:FEN]]
+[[Category:Toxicology]]