• Plasma potassium >6 mmol/L (normal 3.0–5.5 lithium heparin specimen)
• Babies often tolerate concentrations up to 7.5–8.0 mmol/L without ECG changes

• Cardiac arrest
• ECG abnormalities (see below):
  • tall peaked T waves
  • widened QRS complex
  • sine waves (widened QRS complex merging with T wave)
  • prolonged PR interval, bradycardia, absent P wave

Tall, peaked T wave, widening of QRS

Sine wave QRS complex (before cardiac arrest)

• ECG changes as above
• Rapid rise in potassium >7 mmol/L
• Ca²⁺ and Mg²⁺ below normal range
• Oliguria
• Acute kidney injury
• Known cardiac disease 

• Renal failure: secondary to hypoxic ischaemic encephalopathy, sepsis and hypotension, post major surgery, structural abnormalities and nephrotoxic drugs 
• Cellular injury with potassium release e.g. large intraventricular haemorrhage, haemolysis
• Very-low-birth-weight babies without renal failure (non-oliguric hyperkalaemia) in first 12–48 hr
• Excess potassium in IV solutions
• Endocrine (congenital adrenal hyperplasia, pseudohypoaldosteronism)

• Confirm hyperkalaemia. Send free-flowing venous or arterial laboratory sample to avoid haemolysed sample. Be guided by capillary gas sample in the meantime
• If potassium >6.0 mmol/L, send Ca²⁺, Mg²⁺, Cl^-, glucose and urinalysis to guide treatment and help identify cause 
• If potassium >6.0 mmol/L, commence continuous ECG monitoring and assess for risk of arrhythmia (see above)

Serum potassium >6.0 mmol/L (stable with normal ECG)

• Stop all sources of potassium including IV solutions (check PN) and oral supplements 
• Stop all potassium-retaining drugs and potassium-sparing diuretics e.g. spironolactone
• Avoid suxamethonium 
• Review and withhold nephrotoxic drugs e.g. gentamicin
• Recheck U&E 4–6 hrly

Serum potassium >7.0 mmol/L without ECG changes

• As above
• Inform consultant 
• Give salbutamol 4 microgram/kg IV in glucose 10% over 5–10 min; effect evident within 30 min but sustained benefit may require repeat infusion after at least 2 hr
• Give furosemide 1 mg/kg IV
• If serum potassium still >7.0 mmol/L, give soluble insulin 0.1 units/kg IV in 10 mL/kg 10% glucose over 30 min; very effective and has an additive effect with salbutamol
• Repeat U&E 2–3 hrly
• Repeat insulin infusion as necessary until potassium <7.0 mmol/L
• Monitor blood glucose every 15 min for first 2 hr during and after infusion
  • aim for blood glucose 4.0–7.0 mmol/L
• Give sodium bicarbonate 1 mmol/kg (2 mL of sodium bicarbonate 4.2% = 1 mmol) if:
  • pH <7.23 or
  • BE more negative than -8 or 
  • bicarbonate <14 mmol/L
• Correct other electrolyte abnormalities
• Maintain ionised Ca²⁺ >1 mmol/L

Serum potassium >7.5 mmol/L with ECG changes

• As above, but first institute emergency measures below:
  • give calcium gluconate 10% 0.5 mL/kg IV/CVL over 5–10 min 
    • infuse centrally were possible; does not reduce potassium but stabilises myocardium
  • flush line with sodium chloride 0.9% or preferably use a different line 
    • always give separately to bicarbonate or PN (calcium gluconate must not come into contact with any other IV administered drug)
  • give sodium bicarbonate (1 mmol/kg IV over 2 min). Effective even in babies who are not acidotic (2 mL of sodium bicarbonate 4.2% = 1 mmol)
• Repeat U&E hourly

Further treatments: discuss with consultant

• A cation-exchange resin, such as calcium resonium (500 mg/kg rectally, with removal by colonic irrigation after 8–12 hr, repeat every 12 hr. Dose can be doubled at least once to 1 g/kg in severe hyperkalaemia). Useful for sustained reduction in serum potassium but takes many hours to act and is best avoided in sick preterms at risk of necrotising enterocolitis
• If severe hyperkalaemia persists despite above measures in term babies with otherwise good prognosis, contact renal team for consideration of dialysis or exchange transfusion (see Exchange transfusion guideline)

• Recheck serum potassium after each intervention or: 
  • 4–6 hrly in stable/well baby with potassium <7 mmol/L and no ECG changes
  • 2–3 hrly in unwell baby and/or potassium >7 mmol/L with no ECG changes
  • hourly when arrhythmias or ECG changes present with/without renal failure
• Monitor urine output and maintain good fluid balance
• If urine output <1 mL/kg/hr, unless baby volume depleted, give furosemide 1 mg/kg IV until volume corrected
• Treat any underlying cause (e.g. renal failure)
• Review need for further investigations for underlying cause e.g. 17OHP for congenital adrenal hyperplasia

Management of hyperkalaemia in babies