EMed

Hyperkalaemia

Background

Classified on serum level

  • Mild = 5.5 - 6.0mmol/l
  • Moderate 6.1 - 6.9mmol/l
  • Severe >7 mmol/l

Can cause cardiac standstill and VF

Causes

  • Acute renal failure
  • K+ sparing diuretics
  • ACE inhibitors
  • Hyperglycaemia
  • Rhabdomyolysis
  • Adrenal insufficiency
Hyperkalaemic ECG
Tall [ >5mm] T waves (K+ 6-7 mmol/l)
Small broad P or absent P waves
Wide QRS complex (K+ 7-8 mmol/l)
Sinusoidal QRST (K+ 8 - 9 mmol/l)
AV dissociation or VT / VF (K+ >9 mmol/l)

Management

Calcium gluconate

  • 30ml of 10% Ca++ gluconate over 10 minutes
  • Indicated when ECG changes present
  • Antagonises cardiac excitability
  • Does not affect plasma potassium level
  • Duration of protection - minutes. Repeat as necessary
  • Slower (over 30 min) infusion in patients on digoxin

Insulin with glucose

  • Stimulates Na+ - K+ ATP pump and so intracellular uptake of K+
  • Dose = 10iu insulin in 50ml of 50% dextrose given as bolus
  • In children a glucose load of 0.5 g/kg/hr (2.5ml/kg/hr) should be given. If blood glucose rises above 10 mmol/l then insulin should be added at 0.05u/kg/hr
  • Onset of action 15 min, lasts about 1 hour

Salbutamol

  • Binds B2, stimulates CAMP, which stimulates Na+-K+ ATP pump
  • Give 0.5mg (4 µg/kg in children) slow IV
  • or
  • 10mg nebulised Salbutamol (in children 2.5 mg if < 25kg, 5 mg if > 25 kg)
  • Avoid IV admin. in patients with ischaemic heart disease

Sodium bicarbonate

  • No effect on plasma level for 60 min
  • No studies demonstrate clear benefit
  • May be considered in severe acidosis

Sodium polystyrene sulphonate

  • Resin binds K+ in the intestine
  • 50 grams polystyrene in 100-200ml 30% sorbitol or 10% glucose
  • Given PR and left for at least 60 min

Haemodialysis

  • Definitive hypokalaemic measure
  • Rapid fall in plasma level in first hour
  • Especially where hyperkalaemic arrest or other medications have failed

Content by Dr Íomhar O' Sullivan Last review Dr ÍOS 30/05/24.