How to manage acidosis with hyperkalemia in an extreme preterm neonate?

Management of Acidosis with Hyperkalemia in Extreme Preterm Neonates

The management of acidosis with hyperkalemia in extreme preterm neonates requires prompt intervention with calcium chloride (20 mg/kg IV) for cardiac membrane stabilization when ECG changes are present, followed by sodium bicarbonate (1-2 mEq/kg IV) administration to correct acidosis, and insulin with glucose therapy to shift potassium intracellularly. 1

Initial Assessment

1. Confirm true hyperkalemia:

   • Repeat potassium measurement to rule out pseudohyperkalemia (common in hemolyzed samples) 1
   • Check ECG for signs of hyperkalemia (peaked T waves, widened QRS) 1
   • Determine if oliguric or non-oliguric hyperkalemia:
     • Non-oliguric: diuresis usually normal, urinary K >20 mmol/L 2
     • Oliguric: mostly due to renal failure, urinary K <20 mmol/L 2

2. Identify underlying causes:

   • Risk factors for non-oliguric hyperkalemia (NOHK):
     • Lack of antenatal corticosteroids
     • Systemic acidosis
     • Birth asphyxia
     • Massive hematomas
     • Hemolysis
     • Catabolic state 2, 1
   • Assess renal function (serum creatinine, urine output)
   • Check for metabolic acidosis (pH, bicarbonate levels)

Treatment Algorithm

Step 1: Cardiac Membrane Stabilization (for severe hyperkalemia K >7 mmol/L or ECG changes)

• Administer calcium chloride 20 mg/kg IV/IO immediately 1
• Monitor cardiac rhythm continuously

Step 2: Correct Acidosis

• Administer sodium bicarbonate 1-2 mEq/kg IV slowly over 30-60 minutes 1, 3
• For severe metabolic acidosis (pH <7.2 with base deficit >10 mmol/L or bicarbonates <12 mmol/L) 2
• Avoid rapid correction which may cause cerebral edema 3

Step 3: Shift Potassium Intracellularly

• Administer insulin with glucose:
  • Regular insulin 0.1 units/kg/hour with glucose 0.5-1 g/kg/hour 1, 4
  • Monitor blood glucose levels every 30-60 minutes

Step 4: Eliminate Excess Potassium

• If renal function is adequate, consider loop diuretics 1
• For refractory hyperkalemia:
  • Exchange transfusion
  • Peritoneal dialysis (as last resort) 4

Prevention and Ongoing Management

1. Adjust parenteral nutrition:

   • Use "Cl-free" Na and K solutions to reduce risk of hyperchloremic metabolic acidosis 2
   • Limit potassium intake to 40-120 mg/kg/day (1-3 mmol/kg/day) 1
   • Ensure K supply parallels amino acid supply to avoid refeeding-like syndrome 2

2. Monitor closely:

   • Serum electrolytes (K, Na, Ca, Cl)
   • Acid-base status (pH, bicarbonate)
   • Renal function
   • Cardiac monitoring

Special Considerations

• Hyperchloremic acidosis: High cumulative Cl intake (>10 mmol/kg during first 3 days) can induce metabolic acidosis in preterm infants 2
• Refeeding-like syndrome: Early enhanced parenteral nutrition increases endogenous insulin production and promotes K transfer into cells 2
• Relationship between hyperkalemia and acidosis: Hyperkalemia itself can worsen acidosis by suppressing urinary ammonium excretion 5

Common Pitfalls to Avoid

1. Treating pseudohyperkalemia: Always confirm hyperkalemia with proper collection technique before initiating treatment 1
2. Overly rapid correction of acidosis: May lead to cerebral edema and neurological injury 3
3. Ignoring underlying causes: Address the primary cause of hyperkalemia while providing symptomatic treatment
4. Excessive potassium restriction: Inadequate K supply may affect protein synthesis and growth in preterm infants 2
5. Failure to recognize ECG changes: Cardiac monitoring is essential during treatment of hyperkalemia 1