- 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)
- Insulin rate is adjusted according to the hourly BMs (unlike DKA)
- 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)
- Ideally 0.45% saline + 5% glucose + 20mmol/l of KCL
- 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