How is lactic acidosis treated?

Treatment 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), while avoiding bicarbonate therapy in most cases. 1

Classification and Diagnosis

Lactic acidosis is classified into two main types:

• Type A (Hypoxic): Due to tissue hypoperfusion or hypoxia
• Type B (Non-hypoxic): Occurs despite adequate tissue oxygenation 1

Diagnostic criteria include:

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

Treatment Algorithm

1. Identify and Treat the Underlying Cause

• Type A (tissue hypoxia/hypoperfusion):

  • Restore tissue perfusion with appropriate fluid resuscitation
  • Optimize oxygen delivery
  • Treat sepsis according to guidelines
  • Address any circulatory or respiratory failure 1

• Type B (metabolic causes):

  • Discontinue offending medications (metformin, NRTIs)
  • Treat underlying conditions (liver failure, malignancy)
  • Provide thiamine supplementation for alcoholic patients
  • Address short bowel syndrome or bacterial overgrowth if present 1

2. Medication Management

• Discontinue metformin immediately in patients with:

  • eGFR < 30 mL/min/1.73 m² (contraindicated)
  • Signs of lactic acidosis
  • Significant renal impairment
  • Hemodynamic instability 2

• Avoid metformin in patients at risk for lactic acidosis:

  • Sepsis or hypoxia
  • Impaired metformin clearance (renal dysfunction)
  • Impaired lactic acid clearance (liver failure) 3

3. Supportive Care

• Hemodynamic monitoring and vasopressor therapy for marked arterial hypotension 3
• Ventilatory support for respiratory failure 3
• Serial lactate measurements (every 4-6 hours) to assess lactate clearance 1
• Monitor arterial blood gases, plasma osmolarity, and renal function 1

4. Renal Replacement Therapy

• Consider hemodialysis for:
  • Metformin-associated lactic acidosis (metformin is dialyzable with clearance up to 170 mL/min) 2
  • Severe, refractory lactic acidosis with hemodynamic instability 4
  • Note: Standard CRRT with high-volume hemofiltration has limited efficacy for severe lactic acidosis due to relatively small lactate clearance (79 mL/min) compared to rates of lactate overproduction 5

5. Bicarbonate Therapy

• Generally not recommended for routine treatment of lactic acidosis 1, 6
• May be considered only when pH < 7.15 with hemodynamic instability 1
• Caution: Bicarbonate therapy can lead to:
  • Increased lactate production
  • Hypernatremia
  • Hypervolemia
  • Paradoxical intracellular acidosis 7, 8

Special Considerations

Metformin-Associated Lactic Acidosis

• Characterized by elevated blood lactate (>5 mmol/L), anion gap acidosis, and increased lactate:pyruvate ratio 2
• Prompt hemodialysis is recommended to correct acidosis and remove accumulated metformin 2
• Educate patients about symptoms of lactic acidosis and instruct them to discontinue metformin if symptoms occur 2

Fluid Management

• Avoid excessive fluid administration in patients at risk for fluid overload:
  • Elderly patients
  • Those with cardiac, hepatic, or renal dysfunction
  • Patients with ARDS or pulmonary edema 1

Monitoring

• Regular assessment of:
  • Arterial blood gases
  • Serum lactate levels
  • Hemodynamic parameters
  • Renal function 1
• Failure to clear lactate within 6 hours is associated with increased mortality 1

Ineffective Treatments

• Dichloroacetate may improve laboratory values but not survival rates 8
• Sodium bicarbonate has been disproven to ameliorate the hemodynamic depression of metabolic acidemia 6
• Standard hemofiltration cannot counteract lactate production in a meaningful way 8

The management of lactic acidosis remains challenging with high mortality rates. Early identification and aggressive treatment of the underlying cause remain the cornerstone of therapy, while avoiding treatments that may worsen the condition.