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Mitochondrial Disease Clinical Pathway, Emergency Department and Inpatient – Metabolic Acidosis

Mitochondrial Disease Clinical Pathway — Emergency Department and Inpatient

Metabolic Acidosis

Definition pH < 7.3 and/or Bicarbonate < 15 mmol/L
Types of Acidosis
Affecting Children with Mitochondrial Disease
Lactic Acidosis Lactate > 5 mmol/L
Lactate < 5 rarely cause acidosis
Many patients with mitochondrial disease have elevated lactate at baseline
Keto Acidosis BOHB > 3 mmol/L
BOHB is a more sensitive indicator of ketoacidosis
POC urine detects acetoacetate, which is not generated in patients with mitochondrial disease
Renal Tubular Acidosis (RTA) Non-anion gap acidosis resulting from renal wasting of bicarbonate
Associated Signs and Symptoms MS changes, hyperpnea, bradycardia, hypotension, arrhythmia, anorexia, vomiting

Correcting Metabolic Acidosis with IV Sodium Bicarbonate

  • Consult Metabolism for assistance in correcting metabolic acidosis
  • IV sodium bicarbonate-containing fluids are given over 24 hrs to replace the calculated deficit
  • Monitor for hypernatremia and respiratory failure
  • If bicarbonate consistently < 10 mmol/L, telemetry may be needed to monitor for bradyarrhythmia
  • Minimize dextrose to maintain euglycemia in children with lactic acidosis
  • Start enteral feeds ASAP

Calculator: Correcting Metabolic Acidosis with IV Sodium Bicarbonate

Bicarbonate Deficit Calculation (22 mmol/L − bicarbonate in mmol/L) × (weight in kg) × 0.4
NaHCO3 Infusion Instructions
Step 1 Calculate bicarbonate deficit
Step 2 Give 50% of deficit as IV sodium bicarbonate bolus
Bolus dose may not exceed 1-2 mEq/kg, Max dose: 50 mEq
Max infusion rate of 1 meq/kg/hr
Step 3 Calculate remaining deficit = initial deficit [mEq] − bolus dose [mEq]
Step 4 Give remaining bicarbonate via continuous infusion over the next 23 hrs
Sodium bicarbonate replacement can be given as part of maintenance fluids
Example
Patient 4 wk old, 4 kg, serum bicarbonate of 10 mEq/L
Step 1 (22 − 10) × 4kg × 0.4 = 19 mEq
Step 2 Administer sodium bicarbonate 4 mEq (1 meq/kg) IV over 60 mins
Step 3 (19 − 4) = 15 mEq to be run over 23 hrs
Step 4 Run D5 + 41 mEq NaHCO3 + 113 mEq NaCl
This example is running fluids to make a normal saline (154 mEq/L) equivalent to ensure administration of isotonic fluids.
  • Maintenance rate = 16 mL/hr
  • 15 mEq ÷ 23 hrs = 0.65 mEq/hr
  • 0.65 mEq/hr ÷ 0.016 L/hr = 41 mEq/L sodium bicarbonate
  • 154 mEq/L − 41 mEq/L = 113 mEq/L sodium chloride