Treatment of Severe Metabolic Acidosis
The treatment of severe metabolic acidosis prioritizes immediate restoration of tissue perfusion through aggressive fluid resuscitation and correction of the underlying cause, NOT routine bicarbonate administration, which should be reserved only for extreme acidemia (pH <7.15) or specific clinical scenarios. 1, 2
Immediate Resuscitation and Stabilization
Fluid resuscitation is the cornerstone of initial management. Administer isotonic saline (0.9% NaCl) at 15-20 ml/kg/h during the first hour to restore intravascular volume and tissue perfusion. 2 In children with severe malaria, use 20-40 ml/kg of 0.9% saline or 4.5% human albumin solution to safely correct hemodynamic features of shock. 1, 2
Target hemodynamic goals within 6 hours of admission: 3
- Mean arterial pressure (MAP) ≥65 mmHg
- Central venous pressure (CVP) 8-12 mmHg
- Central venous oxygen saturation (ScvO2) ≥70%
Vasopressor management requires careful selection. Use noradrenaline as the first-line agent and adrenaline as second-line; restrict dopamine use as it does not improve renal function. 3, 1, 2 Dobutamine, low-dose dopamine, and milrinone have less impact on mesenteric blood flow if cardiac function support is needed. 3
Etiology-Specific Treatment Algorithms
For Diabetic Ketoacidosis (DKA)
Focus on insulin therapy and fluid resuscitation, NOT bicarbonate. 1, 2 Continuous intravenous insulin is the standard of care for critically ill patients with DKA. 2 Bicarbonate administration has NOT been shown to improve resolution of acidosis or time to discharge in DKA. 2
Bicarbonate is indicated ONLY if pH <6.9-7.0 in DKA. 2, 4 If bicarbonate is required, administer 1-2 mEq/kg IV slowly in children. 2
For Sepsis-Related Acidosis
Prioritize fluid resuscitation and vasopressors over bicarbonate. 1 The effectiveness of sodium bicarbonate to correct metabolic acidosis from septic shock is uncertain, and acidosis may have protective effects. 4
For Chronic Kidney Disease (CKD)
Treat when serum bicarbonate is consistently <18 mmol/L. 1, 2 Oral sodium bicarbonate (2-4 g/day or 25-50 mEq/day) effectively increases serum bicarbonate concentrations. 2 Maintain serum bicarbonate ≥22 mmol/L to prevent bone and muscle metabolism abnormalities. 1, 2
For Acute Kidney Injury with Severe Acidosis
Hemodialysis is the definitive treatment for pH <7.20 with acute kidney injury. 2 Dialysis simultaneously corrects acidemia, removes uremic toxins, and manages volume status. Do not delay dialysis while attempting medical management. 2
Bicarbonate Therapy: When and How
Bicarbonate administration is indicated ONLY in specific scenarios: 3, 1, 5
Indications for Bicarbonate:
- pH <7.15 (or <7.2 in surgical emergencies) 3, 1
- Severe acidosis (pH <7.15) with catecholamine receptor resistance-induced hypotension 3
- Cardiac arrest: rapid IV dose of 44.6-100 mEq initially, then 44.6-50 mEq every 5-10 minutes as needed 5
Dosing Protocol:
For less urgent metabolic acidosis, administer 2-5 mEq/kg body weight over 4-8 hours. 5 Monitor arterial pH and blood gases to guide subsequent doses. 5 Target total CO2 of approximately 20 mEq/L initially, NOT complete normalization in the first 24 hours. 5
Critical Monitoring Requirements
Monitor these parameters frequently during treatment: 3, 1, 2
- Serum potassium (acidosis causes hyperkalemia via transcellular shift; correction causes life-threatening hypokalemia) 1, 2
- Arterial or venous blood gases to assess pH and treatment response 2, 4
- Lactate levels as indication of improvement 3
- Blood pressure and fluid status 2
Once renal perfusion is restored and urine output established, add 20-30 mEq/L potassium (2/3 KCl and 1/3 KPO4) to maintenance fluids. 4
Common Pitfalls to Avoid
Do NOT use furosemide unless hypervolemia, hyperkalemia, or renal acidosis are present. 1, 2 Avoid dopamine to improve renal function. 1, 2 Avoid hypotonic fluids (glucose solutions) for resuscitation. 1, 2
Recognize that bicarbonate may worsen intracellular acidosis, reduce ionized calcium, and produce hyperosmolality. 1, 6 In cardiac arrest, the risks from acidosis exceed those of hypernatremia from hypertonic bicarbonate solutions. 5
Avoid attempting full correction of low total CO2 during the first 24 hours, as this may be accompanied by unrecognized alkalosis due to delayed readjustment of ventilation. 5 Values brought to normal or above normal within the first day are very likely associated with grossly alkaline blood pH. 5
Surgical Emergency Considerations
In unstable patients requiring emergency surgery, definitive treatment can be delayed. 3 Trigger points for damage control surgery include core temperature <35°C, pH <7.2, base deficit >8, and clinical or laboratory evidence of coagulopathy. 3
Initial resuscitation period before surgical intervention is necessary to prevent hemodynamic instability on induction of anesthesia, but time from admission to surgery should not exceed 6 hours in patients with GI perforation and septic shock (0% survival rate when >6 hours). 3