What are the steps for managing metabolic acidosis?

Management of Metabolic Acidosis

The management of metabolic acidosis must prioritize treating the underlying cause rather than routine bicarbonate administration, as sodium bicarbonate has not demonstrated mortality benefit in most acute organic acidoses and may worsen intracellular acidosis. 1

Initial Diagnostic and Assessment Steps

The first critical step is determining whether an anion gap is present, as this guides the entire diagnostic and therapeutic approach 2. Simultaneously assess:

• Arterial or venous blood gas to measure pH, bicarbonate, and PCO2 3, 4
• Serum electrolytes including potassium, as acidosis causes transcellular potassium shift leading to hyperkalemia 1
• Calculate anion gap: (Na+ + K+) - (Cl- + HCO3-) to differentiate mechanisms 5, 2
• Lactate levels if tissue hypoperfusion or shock is suspected 3
• Urine pH and ketones when diabetic ketoacidosis or renal tubular acidosis is considered 3, 2

Etiology-Based Treatment Algorithm

For Diabetic Ketoacidosis (DKA)

Focus treatment on insulin therapy, fluid resuscitation, and electrolyte replacement—NOT bicarbonate. 1

• Initiate continuous intravenous insulin as the standard of care for critically ill patients with DKA 1
• Restore circulatory volume and tissue perfusion as the primary goal 1
• Bicarbonate administration is NOT indicated unless pH falls below 6.9-7.0, as it has not been shown to improve resolution of acidosis or time to discharge 1
• Monitor arterial or venous blood gases to assess treatment response 1

For Chronic Kidney Disease-Associated Acidosis

Treat when serum bicarbonate is consistently <18 mmol/L to prevent bone and muscle metabolism abnormalities. 1

• Oral sodium bicarbonate (2-4 g/day or 25-50 mEq/day) effectively increases serum bicarbonate concentrations 1
• Target bicarbonate ≥22 mmol/L in all CKD patients to prevent protein catabolism, bone disease, and CKD progression 1
• Monitor monthly in maintenance dialysis patients 1
• Avoid citrate alkali salts in CKD patients exposed to aluminum, as they increase aluminum absorption 1

For Acute Severe Metabolic Acidosis (Shock, Cardiac Arrest)

In cardiac arrest, give 1-2 vials (44.6-100 mEq) IV sodium bicarbonate rapidly initially, then 50 mL every 5-10 minutes as indicated by arterial pH monitoring. 6

• For shock-associated acidosis, infuse 2-5 mEq/kg over 4-8 hours initially, monitoring blood gases, plasma osmolarity, arterial lactate, and hemodynamics 6
• Prioritize fluid resuscitation and vasopressors over bicarbonate for sepsis-related acidosis 1
• Do NOT use bicarbonate routinely for lactic acidosis from tissue hypoperfusion, as it may worsen intracellular acidosis 1

For Severe Malaria in Children

Metabolic acidosis resolves with correction of hypovolemia and adequate blood transfusion for anemia—sodium bicarbonate is NOT supported by evidence. 1

• Volume resuscitation with 20-40 ml/kg of 0.9% saline or 4.5% human albumin solution safely corrects hemodynamic features 7
• In children with shock and coma, human albumin solution is preferred over saline (5% vs 46% mortality) 7
• Stop volume resuscitation once signs of circulatory failure reverse 7

For Acute Liver Failure

Identify and treat the underlying cause of alkalosis or acidosis rather than using bicarbonate. 7

• Maintain adequate intravascular volume with careful fluid resuscitation 7
• Use continuous dialysis mode rather than intermittent if renal support is needed 7
• Correct hypoglycemia with continuous glucose infusions 7

Critical Monitoring Requirements During Treatment

Monitor electrolytes, particularly potassium, as acidosis correction shifts potassium intracellularly and can cause life-threatening hypokalemia. 1, 5

• Measure blood pH and gases closely to avoid "overshoot" alkalosis, especially when targeting total CO2 of ~20 mEq/L at end of first day 6, 5
• Assess plasma osmolarity during bicarbonate therapy, as solutions are hypertonic and may cause undesirable sodium elevation 6
• Check serum bicarbonate monthly in CKD patients once stable 1
• Monitor blood pressure and fluid status to ensure bicarbonate doesn't cause hypertension or volume overload 1

Common Pitfalls to Avoid

Do NOT attempt full correction of low total CO2 in the first 24 hours, as delayed ventilation readjustment causes unrecognized alkalosis. 6

• Avoid furosemide unless hypervolemia, hyperkalemia, or renal acidosis are present 1
• Do NOT use dopamine to improve renal function 1
• Avoid hypotonic fluids (glucose solutions) for resuscitation 1
• Do NOT use bicarbonate routinely in organic acidoses without severe pH depression (<7.0-7.2) 1, 6
• Recognize that bicarbonate may worsen intracellular acidosis, reduce ionized calcium, and produce hyperosmolality 1

Specific Bicarbonate Dosing When Indicated

For less urgent metabolic acidosis in adults and older children:

• Initial dose: 2-5 mEq/kg over 4-8 hours depending on severity 6
• Stepwise approach required, as response is not precisely predictable 6
• Reassess after initial infusion and adjust frequency/dose based on clinical response 6
• Target total CO2 of ~20 mEq/L at end of first day, not complete normalization 6