Management of Mitochondrial Disease — Metabolic Acidosis — Clinical Pathway: Emergency Department and Inpatient

Mitochondrial Disease Clinical Pathway — Emergency Department and Inpatient

Metabolic Acidosis

Consult Metabolism for guidance on correction of metabolic acidosis

Definition of Metabolic Acidosis
  • pH < 7.3 and/or Bicarbonate < 15 mmol/L
Types of Acidosis Affecting Mitochondrial Patients
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
Symptoms, Signs with Acidosis
  • MS changes, hyperpnea, bradycardia, hypotension, arrhythmia, anorexia, vomiting

Correcting Metabolic Acidosis with IV Sodium Bicarbonate

  • Consult Metabolism
  • 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 patients with lactic acidosis
  • Start enteral feeds ASAP

Calculator: Correcting Metabolic Acidosis with IV Sodium Bicarbonate

Bicarbonate Deficit Calculation
  • (22 mmol/L - patient bicarbonate in mmol/L) X (weight in kg) x 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)
Maximum 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 hours
Sodium bicarbonate replacement CAN be given as part of maintenance fluids
    Example
    Patient: 4 week old, 4 kg, serum bicarbonate of 10 mEq/L
    Step 1: (22 – 10) x 4kg x 0.4 =19 mEq
    Step 2: Administer sodium bicarbonate 4 mEq (1 meq/kg) IV over 60 minutes
    Step 3: (19 – 4) = 15 mEq to be run over 23 hours
    Step 4: *Run D5 + 41 mEq NaHCO3 + 113 mEq NaCl
    a) Maintenance rate = 16 mL/hr
    b) 15 mEq ÷ 23 hours = 0.65 mEq/hr
    c) 0.65 mEq/hr ÷ 0.016 L/hr = 41 mEq/L Sodium Bicarbonate
    d) 154 mEq/L – 41 mEq/L = 113 mEq/L Sodium Chloride
    • *This example is running fluids to make a normal saline (154 mEq/L) equivalent to ensure administration of isotonic fluids.