What is the management of lactic acidosis?

Management of Lactic Acidosis

The primary treatment for lactic acidosis is to identify and address the underlying cause, with specific interventions determined by the type of lactic acidosis (Type A or Type B). 1

Types of Lactic Acidosis and Initial Management

Type A (Hypoxic) Lactic Acidosis

• Caused by tissue hypoperfusion and hypoxia
• Management priorities:
  • Restore adequate tissue perfusion and oxygen delivery
  • Treat underlying causes: sepsis, shock, cardiac failure, respiratory failure
  • For sepsis-induced lactic acidosis: early antibiotics and source control 1

Type B (Non-hypoxic) Lactic Acidosis

• Occurs without evidence of tissue hypoxia
• Management priorities:
  • Discontinue offending medications (metformin, NRTIs, propofol)
  • Treat underlying conditions (diabetic ketoacidosis, liver failure)
  • For metformin-associated lactic acidosis: immediate discontinuation of metformin and prompt hemodialysis 1, 2

Diagnostic Criteria

• Blood pH < 7.35
• Elevated blood lactate levels (> 5 mmol/L)
• Anion gap acidosis
• Increased lactate:pyruvate ratio 1

Specific Management Approaches

Fluid Resuscitation and Hemodynamic Support

• Correct hypovolemia to improve tissue perfusion
• Ensure adequate oxygen delivery
• Monitor hemodynamics and cardiac rhythm 1

Medication Management

• Immediately discontinue medications associated with lactic acidosis:
  • Metformin: particularly in patients with renal impairment, dehydration, or acute illness 2
  • Nucleoside reverse transcriptase inhibitors (NRTIs)
  • Propofol (with prolonged infusion) 1

Bicarbonate Therapy

• Generally not recommended for routine treatment of lactic acidosis
• May be considered when pH < 7.15 with hemodynamic instability
• Monitor for complications: hypocalcemia, volume overload, paradoxical intracellular acidosis 1, 3

Renal Replacement Therapy

• Indications:
  • Severe metabolic acidosis unresponsive to medical management
  • Metformin-associated lactic acidosis
  • pH < 7.15 with hemodynamic instability 1, 2
• Hemodialysis is particularly effective for metformin-associated lactic acidosis as metformin is dialyzable (clearance up to 170 mL/min) 2

Electrolyte Management

• Monitor and correct electrolyte abnormalities:
  • Potassium (if < 3.5 mmol/L): 0.25 mmol/kg over 30 min
  • Total calcium (if < 2 mmol/L): 0.3 ml/kg 10% Ca gluconate over 30 min
  • Magnesium (if < 0.75 mmol/L): 0.2 ml/kg 50% MgSO4 over 30 min
  • Phosphate (if < 0.7 mmol/L): 0.2 mmol/kg of NaPO4 over 30 min 4

Special Considerations

Metformin-Associated Lactic Acidosis (MALA)

• Characterized by elevated blood lactate (>5 mmol/L), anion gap acidosis, and metformin plasma levels generally >5 mcg/mL
• Risk factors: renal impairment, elderly patients, dehydration, contrast studies, surgery
• Management:
  • Immediate discontinuation of metformin
  • Prompt hemodialysis to correct acidosis and remove accumulated metformin
  • Supportive care in hospital setting 2, 5

Monitoring and Follow-up

• Serial lactate measurements (every 4-6 hours)
• Monitor arterial blood gases, plasma osmolarity, hemodynamics
• Assess lactate clearance (failure to clear within 6 hours associated with increased mortality)
• Monitor electrolytes and renal function 1

Common Pitfalls and Caveats

1. Delayed recognition of the underlying cause: Prompt identification and treatment of the underlying cause is crucial for improving outcomes 6

2. Overreliance on bicarbonate therapy: Sodium bicarbonate administration does not improve cardiovascular function or reduce mortality in severe lactic acidosis and may worsen intracellular acidosis 3, 7

3. Failure to consider hemodialysis early: For severe or medication-induced lactic acidosis (particularly MALA), early hemodialysis can be life-saving 2, 5

4. Inadequate monitoring: Regular assessment of lactate levels, acid-base status, and electrolytes is essential to guide therapy 1

5. Continuing medications that contribute to lactic acidosis: Failure to promptly discontinue medications like metformin in high-risk situations (renal impairment, dehydration) 2

6. Neglecting metabolic derangements: Hypoglycemia, electrolyte abnormalities, and other metabolic disturbances should be corrected 4, 1