Management of Metabolic Acidosis
The management of metabolic acidosis must be directed at 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 Assessment and Diagnostic Priorities
Immediately assess serum electrolytes, particularly potassium levels, as acidosis causes transcellular potassium shift leading to hyperkalemia that requires treatment according to hyperkalemia protocols. 1, 2
Calculate the anion gap as the first step in determining etiology—this distinguishes between high anion gap acidosis (lactic acidosis, ketoacidosis, renal failure, toxic ingestions) and normal anion gap acidosis (bicarbonate loss from GI tract or kidneys, renal tubular acidosis). 3, 4
Obtain arterial blood gas to determine pH and assess severity, particularly in complex cases or when respiratory compensation needs evaluation. 5
Etiology-Based Treatment Algorithm
Diabetic Ketoacidosis
Focus treatment on insulin therapy, fluid resuscitation, and electrolyte replacement—NOT bicarbonate. 1, 2 The American Diabetes Association recommends continuous intravenous insulin as the standard of care for critically ill and mentally obtunded patients, with restoration of circulatory volume and tissue perfusion as the primary goal. 1
- Bicarbonate administration has not been shown to improve resolution of acidosis or time to discharge in DKA. 1
- Bicarbonate therapy is generally not indicated unless pH falls below 6.9-7.0. 1
- Monitor arterial or venous blood gases to assess treatment response. 1
Lactic Acidosis and Sepsis-Related Acidosis
Prioritize fluid resuscitation and vasopressors over bicarbonate administration. 2 The only effective treatment for organic acidosis is cessation of acid production via improvement of tissue oxygenation. 3
- Sodium bicarbonate should not be used to treat metabolic acidosis arising from tissue hypoperfusion in sepsis. 1
- Treatment of acute organic acidosis with sodium bicarbonate fails to reduce morbidity and mortality despite improvement in acid-base parameters. 3
Chronic Kidney Disease-Associated Acidosis
Treat when serum bicarbonate is consistently <18 mmol/L to prevent bone and muscle metabolism abnormalities. 1, 2
- Oral sodium bicarbonate (2-4 g/day or 25-50 mEq/day) effectively increases serum bicarbonate concentrations. 1
- Target serum bicarbonate ≥22 mmol/L to prevent protein catabolism, bone disease, and CKD progression. 1, 5
- Monitor serum bicarbonate monthly once stable, then at least every 4 months. 1, 2
- Correction of acidemia has been associated with increased serum albumin, decreased protein degradation rates, and increased plasma concentrations of branched chain amino acids. 1
Severe Malaria in Children with Metabolic Acidosis
Volume resuscitation with 20-40 ml/kg of 0.9% saline or 4.5% human albumin solution safely corrects hemodynamic features of shock and improves renal function. 6, 2 Metabolic acidosis resolves with correction of hypovolemia and treatment of anemia by adequate blood transfusion—no evidence supports sodium bicarbonate use. 1
- In children presenting in coma with shock, human albumin solution should be considered the resuscitation fluid of choice. 6
- Pulmonary edema is a rare complication (<0.5%) with appropriate volume resuscitation. 6
Bicarbonate Administration: When and How
Indications for IV Bicarbonate (Rare)
In cardiac arrest, a rapid intravenous dose of one to two 50 mL vials (44.6 to 100 mEq) may be given initially and continued at a rate of 50 mL every 5 to 10 minutes if necessary as indicated by arterial pH and blood gas monitoring. 7
In less urgent forms of metabolic acidosis, the amount of bicarbonate for older children and adults over 4-8 hours is approximately 2 to 5 mEq/kg body weight, depending on severity as judged by lowering of total CO2 content, blood pH, and clinical condition. 7
Critical Monitoring During Bicarbonate Therapy
Monitor electrolytes, particularly potassium, as acidosis correction shifts potassium intracellularly and can cause life-threatening hypokalemia. 1, 2
- Bicarbonate solutions are hypertonic and may produce an undesirable rise in plasma sodium concentration. 7
- Administration of bicarbonate may worsen intracellular acidosis, reduce ionized calcium, and produce hyperosmolality. 1, 2
- It is unwise to attempt full correction of low total CO2 content during the first 24 hours of therapy, as this may be accompanied by unrecognized alkalosis. 7
Severe Metabolic Acidosis with Acute Kidney Injury
Hemodialysis is the definitive treatment for patients with severe acidosis (pH <7.20) and acute kidney injury, as it simultaneously corrects acidemia, removes uremic toxins, and manages volume status. 1 Dialysis should not be delayed while attempting medical management, as the acidosis is refractory to conservative measures with this degree of renal impairment. 1
Patients require ICU-level care with nephrology consultation for urgent dialysis. 1
Common Pitfalls to Avoid
Avoid furosemide unless hypervolemia, hyperkalemia, and/or renal acidosis are present. 1, 2
Avoid dopamine in an attempt to improve renal function. 1, 2
Avoid hypotonic fluids (e.g., glucose solutions) for fluid resuscitation. 1, 2
Do not use citrate-containing alkali salts in CKD patients exposed to aluminum salts, as they may increase aluminum absorption. 1
Special Population Considerations
Maintenance Dialysis Patients
Maintain serum bicarbonate at or above 22 mmol/L through dialysate bicarbonate concentration adjustment. 1
Either lactate or bicarbonate can be used as buffer in most CRRT patients, with bicarbonate being preferred in patients with lactic acidosis and/or liver failure. 1
Pediatric Patients
In children with renal tubular acidosis, normalization of serum bicarbonate is important for normal growth parameters. 1
Pediatric clinicians may choose to treat milder acidosis (bicarbonate >18 mmol/L) more aggressively to optimize growth and bone health. 1