What is the treatment for metabolic acidosis?

Treatment of Metabolic Acidosis

Treatment of metabolic acidosis must be directed at the underlying cause rather than routine bicarbonate administration, as the etiology determines the specific therapeutic approach. 1

Initial Assessment and Monitoring

Before initiating treatment, assess serum electrolytes, particularly potassium levels, as acidosis causes transcellular potassium shift leading to hyperkalemia 2. Once treatment begins, monitor closely for hypokalemia as acidosis correction shifts potassium intracellularly and can cause life-threatening hypokalemia 2.

Etiology-Based Treatment Algorithm

Diabetic Ketoacidosis (DKA)

• Focus treatment on insulin therapy, fluid resuscitation, and electrolyte replacement—NOT bicarbonate 1, 2
• Continuous intravenous insulin is the standard of care for critically ill and mentally obtunded patients 1
• Restoration of circulatory volume and tissue perfusion is the primary goal 1
• Bicarbonate administration has NOT been shown to improve resolution of acidosis or time to discharge 1
• Bicarbonate therapy is generally not indicated unless pH falls below 6.9-7.0 1, 3
• When transitioning from IV to subcutaneous insulin, administer basal insulin 2-4 hours before stopping IV insulin to prevent recurrence of ketoacidosis 1

Chronic Kidney Disease (CKD)-Associated Acidosis

Treatment thresholds based on bicarbonate levels:

• Bicarbonate ≥22 mmol/L: Monitor without pharmacological intervention 3
• Bicarbonate 18-22 mmol/L: Consider oral alkali supplementation with or without dietary intervention 3
• Bicarbonate <18 mmol/L: Initiate pharmacological treatment with oral sodium bicarbonate to prevent bone and muscle metabolism abnormalities 1, 2

Oral sodium bicarbonate dosing:

• Typical dose: 0.5-1.0 mEq/kg/day divided into 2-3 doses 3
• Alternative dosing: 2-4 g/day or 25-50 mEq/day 1
• Target: Maintain serum bicarbonate ≥22 mmol/L 1, 3

Monitoring parameters:

• Check serum bicarbonate monthly initially, then at least every 4 months once stable 3, 2
• Monitor blood pressure, serum potassium, and fluid status regularly 3
• Ensure treatment doesn't cause hypertension or hyperkalemia 3

Important caveat: Citrate-containing alkali salts should be avoided in CKD patients exposed to aluminum salts as they may increase aluminum absorption 1

Sepsis-Related Acidosis

• Prioritize fluid resuscitation and vasopressors over bicarbonate 2
• Sodium bicarbonate should NOT be used to treat metabolic acidosis from tissue hypoperfusion in sepsis 3
• Focus on restoring tissue perfusion rather than correcting pH directly 3

Severe Malaria in Children

• Metabolic acidosis resolves with correction of hypovolemia and treatment of anemia by adequate blood transfusion 1
• Volume resuscitation with 20-40 ml/kg of 0.9% saline or 4.5% human albumin solution 2
• No evidence supports sodium bicarbonate use 1

Dialysis Patients

• Maintain serum bicarbonate at or above 22 mmol/L 1
• Monitor serum bicarbonate levels monthly 1
• Either lactate or bicarbonate can be used as buffer in CRRT, with bicarbonate preferred in patients with lactic acidosis and/or liver failure 1

Intravenous Sodium Bicarbonate Administration

When IV bicarbonate is indicated (severe acidosis, cardiac arrest):

Cardiac Arrest Dosing 4

• Initial dose: 1-2 vials (44.6-100 mEq) given rapidly IV
• Continue at 50 mL (44.6-50 mEq) every 5-10 minutes if necessary
• Monitor with arterial pH and blood gas measurements
• Caution: Bicarbonate solutions are hypertonic and may produce undesirable rise in plasma sodium, but in cardiac arrest the risks from acidosis exceed those of hypernatremia 4

Less Urgent Metabolic Acidosis 4

• Dose: 2-5 mEq/kg body weight over 4-8 hours
• Administer in stepwise fashion as response is not precisely predictable 4
• Target total CO2 content of approximately 20 mEq/L at end of first day 4
• Do NOT attempt full correction in first 24 hours as this may cause unrecognized alkalosis due to delayed ventilatory readjustment 4

Monitoring During IV Bicarbonate Therapy 4

• Blood gases
• Plasma osmolarity
• Arterial blood lactate
• Hemodynamics and cardiac rhythm
• Electrolytes, particularly potassium

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
• Recognize that bicarbonate may worsen intracellular acidosis, reduce ionized calcium, and produce hyperosmolality 1, 2
• Avoid overly aggressive correction in the first 24 hours to prevent alkalosis 4

Special Populations

Pediatric Patients

• In children with renal tubular acidosis, normalization of serum bicarbonate is important for normal growth parameters 1
• Clinicians may choose to treat milder acidosis (bicarbonate >18 mmol/L) more aggressively to optimize growth and bone health 3

Patients with Heart Failure

• Be cautious or avoid sodium bicarbonate in advanced heart failure with volume overload, severe uncontrolled hypertension, or significant edema 3
• Consider acetazolamide for loop diuretic-induced contraction alkalosis in patients with chronic hypercapnia 3

Dietary Considerations for CKD Patients

• Increasing fruit and vegetable intake can help treat high net endogenous acid production 3
• This approach may also decrease systolic blood pressure and body weight compared to sodium bicarbonate supplementation alone 3
• Western diets high in animal protein and low in fruits/vegetables can lead to chronic low-grade metabolic acidosis 3

Clinical Benefits of Correction

Correction of acidemia in CKD patients has been associated with 1, 3:

• Increased serum albumin
• Decreased protein degradation rates
• Increased plasma concentrations of branched chain amino acids
• Improved bone histology
• Reduced excess protein catabolism
• Slowed CKD progression