Hyperkalaemia in children

Serum K+> 5.5 mmol/L in children & > 6mmol/L in neonates

 

Potassium has an important role in membrane polarization, especially within cardiac conduction system.  Hyperkalaemia is potentially life threatening, and can result in cardiac arrhythmias or sudden death.

 

Causes

Cell / Tissue breakdown

– Spurious result due to hemolysis, prolonged tourniquet

– Tumor lysis syndrome,

– Rhabdomyolysis (crush injury, prolonged seizure)

– Massive hemolysis, Burns

– Malignant hyperthermia

 

Decreased renal excretion

– Acute / Chronic Renal failure

– Renal tubular disorders, obstructive nephropathy

– Drugs: ACE inhibitors, Potassium sparing diuretics

– Mineralocorticoid deficiency: CAH, Addison disease

 

Increased Potassium intake

– Oral or Intravenous excess potassium administration

– Red cells transfusion

 

Extracellular shift

– Acidosis

– Diabetic Ketoacidosis with low insulin status

– Drugs- Propranolol, NSAID, Digoxin

 

Clinical presentation

– Review clinical features and possible causes leading to Hyperkalaemia.

– Cardiac toxicity with arrhythmias or asystole can precede clinical symptoms

– Some patients have paraesthesias, weakness, and tingling; nausea, vomiting or ileus

– Also respiratory depression, palpitations, cardiac arrest

 

Investigation

Serum K+should be confirmed with a 2nd  ‘good quality’ sample

Review renal function

 

ECG changes begin with peaking of the T waves and increased P-R interval

Progressing to flatten P wave, widened QRS complex

Then Ventricular fibrillation or Asystole

 

Moderate or severe hyperkalaemia requires continuous cardiac monitoring

*A normal ECG does not exclude risk for arrhythmia

 

Also check blood gas, Glucose, CK, Urine electrolytes

May need to consider checking Aldosterone and Cortisol

 

Management

Discontinue K+in IV fluids and any oral potassium supplement

Stop any drug that may increase potassium or reduce its excretion

Alert senior doctor and consider discussion with Renal team or PICU

 

Moderate to Severe hyperkalaemia:

– IV Calcium Gluconate (membrane stabilising effect)

– Salbutamol nebulised (causes intracellular shift)

– Insulin + Glucose infusion (causes intracellular shift)

– IV Bicarbonate correction (to reverse metabolic acidosis)

 

Then consider

– Dialysis (to reduce total body K+)

– Resonium orally / rectally (reduces K+ in GIT)

– IV Hydrocortisone if suspicion of adrenal insufficiency

 

Mild hyperkalaemia

– May not require specific treatment, but confirm with 2ndsample

– Stop any K+supplements or any causative drug

– May require Salbutamol nebulized or oral Resonium