Insulin – Continuous Subcutaneous Insulin Infusion (CSII) [‘Insulin Pump’]


 

Actrapid®[human insulin], Apidra® [insulin glulisine], Fiasp® [insulin aspart], Humalog® [insulin lispro], Humulin® S [human insulin], Insuman® Infusat [human insulin], Insuman® Rapid [human insulin], Lyumjev® [insulin lispro], NovoRapid® [insulin aspart]


  Issues for Surgery


Hypoglycaemia if continued during nil by mouth period.

Risk of Diabetic Ketoacidosis (DKA) if usual regime discontinued and switched to alternative insulin regime but also risk of DKA if CSII continued perioperatively and pump failure occurs (see Further Information).

Increased risk of post-operative infection and delayed wound healing due to poor glycaemic control if discontinued.


  Advice in the Perioperative period


Elective Surgery

The patient’s specialist pump Diabetes Team should be involved in the planning for elective surgery.

If the patient reports that they usually get capillary blood glucose (CBG) <6mmol/mol in the morning, advise them to reduce their basal insulin to 80% of their normal rate on the night before their surgery.  

If the patient reports that they usually get CBG <6mmol/mol during the day, advise them to reduce their basal insulin to 80% of their normal rate on awakening on day of surgery.

Advice on continuation of CSII in the perioperative period is dependent on the type of surgery and number of meals likely to be missed: -

Minor surgery (< 2 hours) / only one missed meal – continue (see Further Information).

  • Monitor CBG hourly at a minimum on day of surgery and aim to keep between 6 and 10mmol/mol1, 2, 3, 4 If patient usually uses another method of monitoring glucose see Further Information.
  • Ensure the cannula and pump is sited away from the operation site (not between the diathermy plate and diathermy if this will be used during surgery– see Further Information)1, 3.
  • Ensure the cannula and the pump can be easily observed and is accessible to the theatre team during the procedure (upper arm is usually a good site for abdominal and lower limb surgery and thigh is usually a good site for head, neck and upper limb surgery)
  • Ensure use of a Teflon® cannula set
  • Ensure patient is aware to bring all necessary pump supplies into hospital with them.

Major surgery (> 2 hours) / more than one meal missed – discontinue1, 2, 3, 4.  Start variable rate intravenous insulin infusion (VRIII) immediately3.

For procedures requiring diathermy or radiological procedures – see Further Information

It should be assumed that during an elective hospital admission, the patient will take responsibility for the CSII pump during their stay, except for the period of reduced consciousness during surgery when another allocated healthcare professional must take on that obligation.

A concise management plan, detailing the planned continuation / discontinuation of the pump during surgery should be documented in the medical notes; together with signed consent of the patient1, 2.

Emergency Surgery

The specialist Diabetes Team should be contact to review the patients and formulate an individual plan. Continuation of CSII will depend on whether the patient is well enough to manage it on his or her own and the type of procedure / duration of fasting as stated above for Elective Surgery. An assessment of the patient’s blood glucose, blood ketones, + / - venous/arterial pH is advised3.

Perioperative Considerations

Check correct connection and functioning of pump. Check CBG every 30 -60 minutes to ensure in target range of 6-10mmol/mol, if CBG rises above 12 mmol/mol, consider pump failure; check blood ketones, commence VRIII and remove pump cannula1.

Post-operative Advice

If Continued 
Move cannula to usual position and check patient satisfied with pump function and glucose control.  Advise patient to check CBG more regularly for few days post-operatively.

If Discontinued
Where the pump has been discontinued, the patient’s pump should be restarted as soon as possible post-operatively when they are able to manage it themselves. 

Where CSII is discontinued for a radiological procedure, it should be immediately reconnected. CSII can be safely suspended / removed for up to 30 minutes at a time without needing alternative insulin1.

Where VRIII has been used, this must be continued for 60 minutes alongside the pump once it has been restarted with hourly CBG checks3. Advise patient to check CBG more regularly for few days post-operatively.

If the patient is unable to manage their CSII post-operatively and they are not nil by mouth (NBM), a basal-bolus regimen is preferable to VRIII3. This should be discussed with the specialist Diabetes Team.


  Interaction(s) with Common Anaesthetic Agents


Reduction of Blood-Glucose Lowering Effect

Substances that may reduce the blood-glucose-lowering effect include sympathomimetics (e.g. epinephrine / adrenaline)5, 6.


  Interaction(s) with other Common Medicines used in the Perioperative Period


Enhancement of Blood-Glucose Lowering Effect

Substances that may enhance the blood-glucose lowering effect and increase susceptibility to hypoglycaemia include sulphonamide antibiotics (e.g. co-trimoxazole)5, 6.

Reduction of Blood-Glucose Lowering Effect

Corticosteroids can reduce the blood-glucose-lowering effect of insulin5. Clinically important hyperglycaemia has been seen7.  Monitor blood glucose concentrations closely when corticosteroids are given to patients with diabetes7.

Somatostatin analogues (octreotide and possibly lanreotide) may increase or decrease insulin requirements4, 5, 6, 7, but most patients with type 1 diabetes are likely to require a reduction in insulin dose, with some studies suggesting a potential reduction of 50% in patients taking concomitant octreotide6, 7.  Monitor CBG when somatostatin analogues are given to patients with diabetes7.


  Further Information


Continuous subcutaneous (s/c) insulin infusion (CSII)

This is a continuous s/c infusion of insulin (usually in the form of a rapid-acting insulin or soluble insulin), delivered by a programmable pump. It is designed to mimic physiological insulin delivery over 24 hours with basal and bolus insulin infusions of rapid-acting insulin analogue8. They are currently used by approximately 15% of people with type 1 diabetes1.

Risk of Diabetic Ketoacidosis (DKA)

As there is no long-acting insulin component in CSII, fasted patients are at risk of DKA in case of failure, disconnection or occlusion of the pump.  While the patient is sedated / anaesthetised this risk can be mitigated by regular CBG monitoring and intravenous access.  If CBG >12mmol/mol check blood ketones, remove cannula and commence VRIII immediately1.

Safe Prescribing of Insulin 

Insulin should be prescribed according to National Patient Safety Agency (NPSA) recommendations for safe use of insulin, with the brand name and units written in full1, 2, 8.

Safe Continuation of CSII

The Centre for Perioperative Care (CPOC) has developed comprehensive guidance to support Trusts in facilitating the continued use of CSII in patients who meet agreed criteria, have been fully informed of the risks and alternatives available and wish to continue their CSII.  Health Boards / Trusts should ensure that they have pathways in place to allow patients to continue to use their CSII when the anticipated fasting period is only one missed meal1, 3.   

Procedures Requiring Diathermy / Radiological Procedures

The manufacturers of insulin pumps advise that CSII should not be continued in the presence of diathermy, but this is based on perceived rather than actual risk1

Furthermore, current manufacturers guidelines state that CSII pumps must not be exposed to screening radiological procedures (CT, MRI, X-Ray)1, 2, 3. However, this advice is probably based on lack of evidence rather than evidence of harm.  US guidance advocates that the pump can remain in place for X-Ray / CT, ensuring that the pump is covered by the lead apron4.

Monitoring

All patients with CSII should have CBG monitoring on day of surgery.  If patient usually uses continuous glucose monitors (CGM) this assesses subcutaneous interstitial glucose concentrations which lag behind CBG by approximately 15 minutes and so is not suitable for sole use in sedated / anaesthetised surgical patients1.

 

  References


  1. Centre for Perioperative Care. Guideline for Perioperative Care for People with Diabetes Mellitus Undergoing Elective and Emergency Surgery (March 2021). Available at: https://cpoc.org.uk/guidelines-resources/guidelines [Accessed on 8th March 2021]
  2. Partridge H, Perkins B, Mathieu S et al. Clinical recommendations in the management of the patient with type 1 diabetes on insulin pump therapy in the perioperative period: a primer for the anaesthetist. British Journal of Anaesthesia 2016; 116(1): 18-26
  3. DTN UK. Clinical Guideline: Guidelines for managing subcutaneous insulin infusion CSII, or ‘insulin pump’ therapy in hospitalised patients. Available at www.abcd.care [Accessed 10th August 2019]
  4. Umpierrez GE, Klonoff DC. Diabetes Technology Update: Use of Insulin Pumps and Continuous Glucose Monitoring in the Hospital. Diabetes Care. 2018;41:1579-1589
  5. Summary of Product Characteristics – Actrapid® (human insulin) 100 international units/ml, Solution for Injection in a vial. Novo Nordisk Limited. Accessed via www.medicines.org.uk 01/03/2021 [date of revision of the text October 2020]
  6. Insulin. In: Brayfield A (Ed), Martindale: The Complete Drug Reference. London: The Royal Pharmaceutical Society of Great Britain. http://www.medicinescomplete.com [Accessed 1st March 2021]
  7. Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 1st March 2021]
  8. Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 1st March 2021]