What insulin can be given IV?

Introduction

This section provides guidance and links to appropriate guidelines on the use of variable rate intravenous insulin infusion (sliding scale) for medical patients.

Indications for VRIII (sliding scale)

For patients with diabetes who are hyperglycaemic or with hospital related hyperglycaemia who are unable to take oral fluid/food, who are acutely unwell and/or for whom adjustment of their own insulin regimen is not possible. Particularly the following groups of patients:

• Patients with type 1 diabetes who are unable to eat and drink

• Patients with type 1 diabetes with recurrent vomiting (exclude DKA)

• Patients with type 1 or 2 diabetes and severe illness with need to achieve good glycaemic control e.g. sepsis

SPECIAL CIRCUMSTANCES: The guidelines for rate of fluid administration, choice of substrate and glycaemic targets may differ for ACS, stroke, TPN/enteral feeding, steroid use and pregnancy. Follow local guidelines and seek advice from the diabetes team if unsure.

Practical aspects of prescribing VRIII

• Withhold usual diabetes treatment during the VRIII but if the patient is on sub-cutaneous background/basal insulin (Levemir, Lantus, Abasaglar, Toujeo, Tresiba, Insulatard, Insuman basal or Humulin I) prior to VRIII, continue this whilst on insulin infusion. All other diabetes medication should be withheld.

• Actrapid is the most commonly used insulin for VRIII (Actrapid 50 units is added to 49.5 ml of 0.9% sodium chloride)

• Always ensure that the substrate (dextrose) is prescribed with VRIII to prevent the risk of hypoglycaemia (see section on choice of fluids below). Intravenous Insulin infusion should not be administered without substrate unless undertaken in a critical care setting and upon senior advice.

• Capillary blood glucose levels CBGs must be monitored hourly whilst on VRIII.

• Review the patient within 6 hours to make sure that CBGs are in target range. If the CBGs are persistently above 12 mmol/L and NOT falling upgrade the scale and review again within 6 hours. Check ketones 4 hourly in patients with Type 1 diabetes and at least once in patients with Type 2 diabetes if CBG readings are persistently above 12 mmol/L whilst on VRIII.

Choice of fluid

Intravenous fluids are administered with VRIII to avoid hypoglycaemia by providing substrate (dextrose) at a steady rate for the insulin infusion and to maintain fluid and electrolyte balance.

Key factors to consider while prescribing fluids for VRIII

1. Aim to maintain steady rate of glucose infusion and alter rate of insulin to achieve target blood glucose control unless there is risk of fluid overload. Altering fluid rate or type of substrate frequently will lead to high variability in glucose levels.

2. Choice of fluids

First choice (NOTE: not readily available in most trusts therefore likely to have to choose from second choice options)

0.45% NaCl and 5% glucose with

0.3% KCl (40 mmol/L) if serum K is 3.5-5.5 mmol/L

Second choice:

5% glucose with 40 mmol/L KCl at 125ml/hr if serum K is 3.5-5.5 mmol/L

NOTE: Patients needing VRIII for more than 24 hours will need fluid containing sodium chloride alongside the dextrose to avoid hyponatremia

Or

0.18% NaCl with 4% glucose with 20 or 40 mmol/L KCl at 125 ml/hr if serum K is 3.5-5.5 mmol/L

3. K⁺ supplementation: Aim to maintain K⁺ 3.5-5 mmol/L

Aim to keep K⁺ 4.0 - 5.0 mmol/L.

• If serum K⁺>5.5 no additional K⁺ but reassess serum K⁺ regularly

• If serum K⁺ <3.5 senior review as extra potassium needs to be given

4. Rate of fluid infusion: Rate of infusion depends on the fluid status of the patient. If there is no risk of fluid overload substrate rate of 125mls/hour is acceptable. In patients with risk of fluid overload, frail and elderly, use 5% or 10% dextrose at 83ml/hour. Consider higher strength substrate (10% or 20% glucose) at 42mls/hour if further fluid reduction is needed

5. Seek specialist advice or refer to specific local guidance for patients with hyponatremia, renal and hepatic conditions and for those on HDU and ITU.

Monitoring CBGs while on VRIII

• Monitor CBGs on an hourly basis

• Aim for CBGs are in the range 6 -10 mmol/L (4 - 12 mmol/L acceptable)

• If the CBGs are above the target range, firstly ensure that the lines are patent. You may then need to adjust the insulin infusion rate.

• Consider insulin scale adjustment if CBG are persistently above 12.0mmol/l within 6 hours of commencing a VRIII or of subsequent scale change, unless there is a steady improvement.

• Managing hypoglycaemia on VRIII

• Stop the VRIII and treat the hypo (CBG <4.0 mmol/L) as per local hypoglycaemia guidelines

  • Check that cannula and lines are all patent and that VRIII has been correctly set up

  • Restart VRIII when CBG > 4.0mmol/l. VRIII should not be stopped for >20 minutes

• STEP DOWN to the lower scale/ customised scale when the VRIII is restarted to prevent further hypoglycaemia

  • If hypoglycaemia recurrent despite stepping down to a lower scale consider switching to a higher strength substrate (e.g. 10% or 20% Dextrose) and always think about whether the VRIII is still required or can the patient be switched to usual treatment

ITS SAFE USE OF VRIII

Safe maintenance of VRIII

Review the need for VRIII on a daily basis – if not sure, ask the diabetes team for help. Daily review should include review of fluid status.

Monitor urea and electrolytes every day (at risk of hyponatraemia and hypokalaemia)

Stopping the VRIII and safe switch to subcutaneous insulin

• Ensure the patient is able to eat and drink

• CBGs are in the range 6 – 10 mmol/L (4 - 12 mmol/L acceptable)

• Discontinue at a meal-time (preferably a meal where usual diabetes medication is given)

ITS ANIMATION:VRIII TO SC INSULIN

Insulin treated patients

• For patients on basal bolus regimen who continued basal insulin whilst on VRIII, restart usual diabetes treatment together with a meal and stop VRIII 30-60 minutes after the meal time insulin has been given and patient has eaten

• If basal had been stopped at the time of VRIII, it must be restarted prior to stopping VRIII.VRIII can be stopped 30-60 after both the basal AND meal time insulin has been given and patient has eaten. If it is necessary to stop VRIII but basal insulin is not due for several hours, give half the usual dose of the usual basal insulin. This will provide background insulin cover until the usual dose can be recommenced.

• For patients on biphasic/mixed insulin regimen, restart usual dose of insulin when it is due (breakfast or evening meal) and stop VRIII 30-60 minutes after insulin has been given and patient has eaten. If it is necessary to stop VRIII but the mixed insulin is not due for several hours, give half the usual dose of the insulin with lunch. This will provide background insulin until the usual dose can be recommenced

For non-insulin treated patients

Recommence the normal treatment prior to discontinuing VRIII. This is likely to co-incide with a meal. A 30-60min overlap is still required. Ensure that there are no contra-indications to restarting the previous diabetes treatment (eg, changes in eGFR).

Beware of the commonly reported VRIII errors

Medical errors:

• Prescribing VRIII without substrate – risk of hypoglycaemia!

• Wrong insulin infusion rate or not adjusting according to hourly CBG reading

• Background insulin not continued alongside VRIII

• Delays in VRIII starting Errors with IV to SC switch

Nursing errors:

• Use of VRIII infusion pump with no label on it / insulin expired

• Accidental overdose due to setting incorrect pump rate

• Accidental disconnection of infusion – risk of DKA for patients with type 1 diabetes!

• Poor CBG monitoring/documentation

• Errors with IV to SC switch

Link

• JBDS guidance – VRII guidance

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Can Humalog be given IV?

Can Humulin insulin be given IV?

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