Metabolic acidosis resident survival guide: Difference between revisions
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===Step 1=== | ===Step 1=== | ||
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{{familytree | | | | | | | | | | | A01 | | | | | |A01= | {{familytree | | | | | | | | | | | A01 | | | | | |A01='''pH<7.35''' <br> And <br> ['''HCO3<sup>2-</sup>]<24 meq/L'''}} | ||
{{familytree | | | | | | | | | | | |!| | | | | | | | }} | {{familytree | | | | | | | | | | | |!| | | | | | | | }} | ||
{{familytree | | | | | | | | | | | B01 | | | | | |B01= | {{familytree | | | | | | | | | | | B01 | | | | | |B01='''Metabolic acidosis'''}} | ||
{{familytree | | | | | | | | | | | |!| | | | | | | | }} | {{familytree | | | | | | | | | | | |!| | | | | | | | }} | ||
{{familytree | | | | | | | | | | | B02 | | | | | |B02= | {{familytree | | | | | | | | | | | B02 | | | | | |B02='''Calculate the anion gap (AG)''' <br><br> Na<sup>+</sup> - Cl<sup>-</sup> - HCO3<sup>2-</sup>}} | ||
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{{familytree | | | C01 | | | | | | C02 | | | | | | | C03 |C01= | {{familytree | | | C01 | | | | | | C02 | | | | | | | C03 |C01='''Low AG'''<br> AG<8|C02= '''Normal AG''' <br> 8<AG<16 |C03= '''High AG''' <br> AG>16 }} | ||
{{familytree | |,|-|^|-|.| | | | | |!| | | | | | | | |!| }} | {{familytree | |,|-|^|-|.| | | | | |!| | | | | | | | |!| }} | ||
{{familytree | D01 | | D02 | | | | |!| | | | | | | | |!| | |D01= | {{familytree | D01 | | D02 | | | | |!| | | | | | | | |!| | |D01='''Check albumin'''<br><br>Correct the AG if albumin is low<br>For every decrease of 1 g/dl of albumin, AG is decreased by 2.5 meg/L|D02='''Check Ca<sup>2+</sup>, Mg<sup>2+</sup>, K<sup>+</sup>, immunoglobulins'''<br><br> High levels of these unmeasured cations decrease the AG}} | ||
{{familytree | | | | | | | | | | | E01 | | | | | | | E02 | |E01= | {{familytree | | | | | | | | | | | E01 | | | | | | | E02 |~|~| E03 |E01='''Check urine AG'''|E02='''Check ΔAG/ΔHCO3<sup>2-</sup>'''|E03= R/O low Ca<sup>2+</sup>, Mg<sup>2+</sup>, K<sup>+</sup>}} | ||
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{{familytree | | | | | | | | F01 | | | | F02 | | F03 | | F04 | | F05 |F01= | {{familytree | | | | | | | | F01 | | | | F02 | | F03 | | F04 | | F05 |F01='''Low urine AG'''<br><br>|F02='''Normal urine AG'''<br><br>|F03=ΔAG/ΔHCO3<sup>2-</sup><1|F04= 1<ΔAG/ΔHCO3<sup>2-</sup><2 |F05=ΔAG/ΔHCO3<sup>2-</sup>>2 }} | ||
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Revision as of 02:58, 2 August 2013
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Metabolic acidosis Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Metabolic acidosis resident survival guide On the Web |
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American Roentgen Ray Society Images of Metabolic acidosis resident survival guide |
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Risk calculators and risk factors for Metabolic acidosis resident survival guide |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ogheneochuko Ajari, MB.BS, MS [2]
Definition
Metabolic acidosis is a state in which the blood pH is low (less than 7.35) due to increased production of H+ by the body or the inability of the body to form bicarbonate (HCO3-) in the kidney.
Causes
Life Threatening Causes
Common Causes
Low Anion Gap Metabolic Acidosis
Normal Anion Gap Metabolic Acidosis
The mnemonic for the most common causes of a normal-anion gap metabolic acidosis is "DURHAM."
- D- Diarrhea
- U- Ureteral diversion
- R- Renal tubular acidosis
- H- Hyperalimentation
- A- Addison's disease, acetazolamide, ammonium chloride
- M- Miscellaneous: congenital chloride diarrhea, amphotericin B, toluene
High Anion Gap Metabolic Acidosis
The mnemonic "MUDPILES" is used to remember the common causes of a high anion gap.
- M - Methanol/ Metformin
- U - Uremia
- D - Diabetic ketoacidosis
- P - Paraldehyde/ Propylene glycol
- I - Infection/ Ischemia/ Isoniazid
- L - Lactic acidosis
- E - Ethylene glycol/ Ethanol
- S - Salicylates/ Starvation
Management
Step 1
| pH<7.35 And [HCO32-]<24 meq/L | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Metabolic acidosis | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Calculate the anion gap (AG) Na+ - Cl- - HCO32- | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Low AG AG<8 | Normal AG 8<AG<16 | High AG AG>16 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Check albumin Correct the AG if albumin is low For every decrease of 1 g/dl of albumin, AG is decreased by 2.5 meg/L | Check Ca2+, Mg2+, K+, immunoglobulins High levels of these unmeasured cations decrease the AG | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Check urine AG | Check ΔAG/ΔHCO32- | R/O low Ca2+, Mg2+, K+ | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Low urine AG | Normal urine AG | ΔAG/ΔHCO32-<1 | 1<ΔAG/ΔHCO32-<2 | ΔAG/ΔHCO32->2 | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Step 2
Shown below is the algorithm summarizing the management of metabolic acidosis
| History, symptoms and physical examination Blood pH < 7.35 | |||||||||||||||||||||||||||||||||||||||||
| Physical examination Eyes Extremities Neurologic (cranial nerves) | Labs/EKG Anion gap, Arterial blood gas analysis Electrolytes (Na, K, Cl, HCO3) CBC Serum lactate, ketone Urinalysis Toxicological screening (salicylate, methanol, ethylene glycol) EKG for arrhythmias | History Arrhythmias Kussmaul breathing Headache, altered mental status | |||||||||||||||||||||||||||||||||||||||
| Place patient on EKG monitor for arrhythmias, hyperkalemia | Replace electrolytes if there are losses | If DKA, IV Insulin, normal saline Potassium and phosphate may be necessary | Send consult to nephrologist for dialysis for renal failure, poisoning | Toxicological consult | |||||||||||||||||||||||||||||||||||||
| IV bicarbonate if there is cardiac arrhythmias 50-100mmol while monitoring arterial blood gas readings | Detoxification agents/toxin antidotes Fomepizole Activated charcoal Emesis Folic acid for methanol overdose Thiamine and pyridoxine for ethylene glycol overdose | ||||||||||||||||||||||||||||||||||||||||
Do's
- Treatment of the underlying cause should be the primary therapeutic goal.
- Bicarbonate should be given only when there is a severe case of acidosis with an arterial pH of less than or equal to 7.2
- Patient should be placed on SaO2 and blood pressure/heart rate monitor
- Consider intubation and ventilation for airway if the SaO2 level is deteriorating or there is a loss of consciousness
- Consider doing catherization to monitor the urine output and obtaining urine for urinalysis
Dont's
- Do not administer vasoconstrictors in the presence of lactic acidosis