Insulin Infusions

  • There are 2 main types to consider:
    • Fixed Rate Infusion 
    • Variable Rate IV Insulin Infusion (VRIII) – aka the ‘sliding scale’
Fixed rate insulin infusion
  • Used in DKA + HHS
    • E.g. in DKA giving 0.1units/kg/hour of Actrapid insulin
  • Essentially giving insulin at a constant rate
    • Do not give glucose with this since trying to drop glucose
Variable Rate IV Insulin infusion – the sliding scale
  • Used to maintain glucose when patients are not eating (e.g. during surgery)
  • 2 bags are infused at a given rate according to hourly BGL
  • First bag: Insulin bag – 50u of Actrapid in 49.5ml of 0.9% saline (as with DKA)
    • Insulin rate is adjusted according to the hourly BMs (unlike DKA)
      • Use a chart to determine the rate (see below)
  • Second bag: Fluid infusion
    • Ideally 0.45% saline  + 5% glucose + 20mmol/l of KCL
      • Do not use glucose if  >12mmol/l (e.g. use saline alone or Hartmann’s)
    • This is run at a constant 50ml/hr (i.e. 1 bag over 20 hours)

  • NB only the insulin is adjusted
    • I.e. the sliding scale applies to insulin- not glucose which is constant at 50ml/hr
  • Both infusions are given through the same cannula to reduce the risk of only one drug being given
    • However, still two separate bags
    • Can still have one line blocked to cause hyper/hypoglycaemia