How to manage lactic acidosis?

Management of Lactic Acidosis

Immediate Priority: Identify and Aggressively Treat the Underlying Cause

The cornerstone of lactic acidosis management is identifying and treating the underlying etiology—sodium bicarbonate administration lacks evidence for improving outcomes and may cause harm. 1

Initial Assessment and Stabilization

Restore tissue perfusion immediately if shock is present with fluid resuscitation using 15-20 mL/kg/h isotonic saline initially. 1 This addresses Type A lactic acidosis from circulatory disorders, cardiac failure, or inadequate tissue perfusion. 1

Discontinue offending medications immediately:

• Stop metformin in all cases of suspected metformin-associated lactic acidosis (MALA). 1, 2 The FDA label explicitly warns that metformin decreases liver uptake of lactate, increasing blood lactate levels and risk of lactic acidosis. 2
• Discontinue NRTIs (stavudine, didanosine) in HIV patients, as these inhibit DNA polymerase γ and cause mitochondrial dysfunction. 3, 1 This carries high mortality without intervention. 1
• Withhold metformin 48 hours before contrast procedures when eGFR is 30-60 mL/min/1.73 m². 3, 2

Diagnostic Workup

Obtain arterial blood gas and lactate level using proper technique:

• Use prechilled fluoride-oxalate tubes transported immediately on ice. 3, 1
• Process within 4 hours of collection. 3, 1
• Collect without tourniquet or fist-clenching. 3, 1

Interpret lactate levels:

• 2-5 mmol/L: Elevated, correlate with symptoms. 3, 1

• 5 mmol/L: Abnormal. 3, 1, 2

• 10 mmol/L: Serious/life-threatening. 3, 1

Calculate anion gap: Na - (Cl+CO₂) >16 suggests lactic acidosis. 3, 1

Check for metformin-associated lactic acidosis characteristics:

• Blood lactate >5 mmol/L. 2
• Anion gap acidosis without ketonuria/ketonemia. 2
• Increased lactate:pyruvate ratio. 2
• Metformin plasma levels generally >5 mcg/mL. 2

Specific Treatment Based on Etiology

For sepsis-related lactic acidosis:

• Obtain blood cultures and administer antibiotics within 3 hours. 1
• Provide aggressive source control. 1
• Ensure hemodynamic support. 1

For D-lactic acidosis (short bowel syndrome with preserved colon):

• Restrict mono/oligosaccharides. 1
• Encourage polysaccharides (starch). 1
• Administer thiamine supplements. 1
• Give broad-spectrum antibiotics. 1

For metformin-associated lactic acidosis:

• Initiate prompt hemodialysis immediately to correct acidosis and remove accumulated metformin (clearance up to 170 mL/min under good hemodynamic conditions). 2 Hemodialysis has often resulted in reversal of symptoms and recovery. 2
• Prolonged or repeated dialysis may be necessary because metformin has a large volume of distribution and accumulates in erythrocytes and intestinal cells, causing rebound lactic acidosis after initial dialysis. 4

The Bicarbonate Controversy: Do NOT Use Routinely

Sodium bicarbonate is explicitly NOT recommended for hypoperfusion-induced lactic acidemia with pH ≥7.15, as it does not improve hemodynamics or reduce vasopressor requirements. 1 The Surviving Sepsis Campaign guidelines state bicarbonate:

• Does not improve hemodynamics or cardiovascular function. 1
• May increase lactate production. 1
• Causes hypernatremia and volume overload. 1
• Generates CO₂. 1
• Has never been shown to improve survival. 1, 5

Supportive Measures

Consider thiamine supplementation to address potential pyruvate dehydrogenase dysfunction. 1

Monitor for respiratory failure as progressive mitochondrial toxicity can cause tachypnea and dyspnea requiring mechanical ventilation. 3

Critical Pitfalls to Avoid

Do not continue metformin during acute illness. Most metformin-associated lactic acidosis occurs when patients continue the drug during concurrent acute illness (sepsis, fever, diarrhea, vomiting) that reduces renal clearance. 6 Patients should be educated to stop metformin and seek medical care during any acute illness. 4

Do not delay hemodialysis in MALA. Prompt hemodialysis is the definitive treatment and should be instituted immediately upon diagnosis. 2

Do not ignore hyperlactatemia even without hypotension. Lactate ≥2 mmol/L indicates sepsis severity and persistent elevation may indicate occult tissue hypoperfusion. 1

Recognize high-risk populations:

• Elderly patients (>65 years) have greater risk due to hepatic, renal, or cardiac impairment. 2
• Patients with eGFR <30 mL/min/1.73 m² should never receive metformin. 3, 2
• Pregnant patients on stavudine/didanosine combinations have experienced fatal lactic acidosis. 3