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