Potassium

The average child in DKA is depleted in total body potassium irrespective of plasma level [37]

• Average losses are 3-6mmol/kg [38-42]
• i.e. our 20ml/kg boy in the previous example will be deficient by around 100mmol!

In addition, once insulin is started potassium will be driven into the intracellular compartment & plasma levels with decline rapidly. [39]

ECG changes & cardiac arrhythmias can occur with hypokalaemia

• Therefore (unless the child is anuric):
  • Always ensure every 500ml bag contains 20mmol potassium (40mmol/L)
  • Check electrolytes 2 hours after the start of fluid management & then at least 4 hourly
  • Use a cardiac monitor to detect T wave changes
  • If K<3mmol/L discuss with critical care as central access will be required for higher concentration replacement

Learning bite

Potassium should be added to fluid regardless of serum level unless the patient is anuric.