Continuous Subcutaneous Insulin Infusions: Perioperative Management

Objectives

Updated guidance on managing patients with Continuous Subcutaneous Insulin Infusion pumps
For adult, non-obstetric patients only

Scope

Background Information:

Subcutaneous insulin pumps delivering a CSII are used by an increasing number of people with Type I diabetes as an alternative to regular daily insulin injections. Pumps are standard care for Under 18’s with T1DM and most continue after 18^th birthday so we will see more and more.

Via plastic tubing and a S.C. cannula an insulin pump will continuously administer a short acting insulin infusion to mimic the basal levels of insulin normally produced by the pancreas.

On demand from the patient, a pump is also capable of administering a bolus of insulin to cover carbohydrate intake or correct a high blood sugar level.

General Principles of Management:

Prolonged disconnection of the pump without administration of alternative insulin will result in DKA! The pump is only delivering short acting insulin. The Pump should not be disconnected for more than 1 hour
Aim for a blood sugar between 6-12mmol/L during patient’s stay.
Check capillary blood sugars regularly, at least hourly while under a G.A. or sedation.
Treat low blood sugars as normal, e.g. 15 to 20g of glucose = 100mls 20% Dextrose i.v.
Your patient can treat high blood sugars via corrective doses from their pump.
Listen to and involve your patient they will be skilled in managing their diabetes and pump.
Pumps can be disconnected from a patient for up to one hour without ill effect.
Insulin pumps cost several thousand pounds and some are not waterproof keep them safe!
Shield pumps from strong radiation or electromagnetic fields as they may damage the pump.

Preoperative Considerations:

Gain consent and ensure a shared decision-making process is undertaken regarding the use of CSII during the peri-operative period. Possible peri-operative strategies are listed below.
Ask the person with diabetes to monitor their CBG hourly on the day of surgery and aim to keep their glucose levels between 6–12mmol/l from day of admission.
If the person with diabetes usually runs with CBG’s less than 6mmol/l during the day, inform the person with diabetes to reduce basal insulin delivery to 80% of normal on the day of surgery.
Discuss with the person with diabetes on where to site their cannula and pump on the day of admission.
Suggest to the person with diabetes (if possible) to use a TeflonR cannula set on the day of surgery. The TeflonR cannula needs to observable and accessible during their time in theatre, and not near the operative field. The upper arm is generally a good place for abdominal and lower limb surgery, whilst the thigh is generally a good place for head, neck and upper limb surgery.
The pump needs to be positioned so that it can be observed to ensure correct functioning and must not be in between the diathermy plate and the diathermy.
Ask the person with diabetes to bring in sufficient consumables, including spare cannulas, infusion sets and insulin. SC cannula need to be changed every 2-3 days

In addition to the above pick one of the 3 peri-operative strategies below depending on the type of surgery being undertaken and anesthetist/patient preference. Discuss and agree plan with your patient – they will be very experienced at using their pump. Please consider using the discussion points in Appendix A to guide your thoughts and those of the patient.

Perioperative Strategies for the use of Continuous Subcutaneous Insulin Infusions (CSII).

Strategy 1, Disconnect the Pump:

Suitable for Short Day Case Procedure < 1 hour duration

Ask the patient to disconnect their pump in the anaesthetic room prior to induction of anaesthesia. Keep the pump safe and return it to the patient in recovery.
Proceed with surgery, protect SC cannula site in theatre and during transfers.
Ask the patient to reconnect the pump in recovery.

Strategy 2, Keep the Pump Running:

Suitable for Day Case Procedures (less than one Missed Meal).

Prior to induction of anaesthesia ask the patient to “lock” their pump to prevent an accidental bolus of insulin while under GA or sedation.
Protect pump and SC cannula site while in theatre and undergoing transfers
Confirm that SC cannula site is outside the surgical prep field

Strategy 3, Disconnect the Pump and Start a Variable Rate Intravenous Insulin Infusion (VRIII):

Suitable for Major or Emergency Surgery

Commence VRIII (aka sliding scale) after patient has disconnected their pump either on the ward or anaesthetic room. Ensure pump is kept safe.
Continue VRIII until the patient is ready to eat, then reconnect the patient’s pump 30mins before disconnecting the sliding scale. The patient may be required to fit a new SC cannula if the existing one is more 2-3 days old.
Allow the patient to bolus insulin via their pump to cover any carbohydrate intake or high blood sugars

Any Questions regarding this guidance or the management of surgical patients with diabetes please contact Dr Simon Heaney or on call diabetes registrar

Appendix A

Benefits of CSII

Avoidance of VRIII with its intrinsic dangers.
Risk of hospital acquired DKA caused by transition issues to and from VRIII are eliminated.
Risks of electrolyte and fluid abnormalities that are associated with the use of the VRIII are eliminated.
Risk of hospital acquired hypoglycaemia that is associated with use of VRIII are eliminated.
Avoidance of changing to and from MDI (multiple daily injections) during the perioperative period.
Avoidance of individually calculated dose of long-acting insulin analogue with risk of omission and miscalculated dose eliminated.
Person with diabetes has familiarity and can more easily continue self-management of diabetes.
Facilitates day surgery with its intrinsic benefits.

Risks

Failure of pump and/or cannula.
Manufacturers do not advocate that pumps to be used near diathermy/X-ray machines.
Not easily titratable by clinical teams who are not familiar with CSII, to counter the glycaemic variability that occurs during major surgery.
Anaesthetist may not be familiar with CSII and possible alarms.
No basal insulin so rapid ketogenesis in the fasted person with diabetes in case of failure/disconnection/occlusion (people are safely able to remove CSII for 30 minutes to allow bathing and swimming). This risk is mitigated by regular CBG testing and by putting in place IV lines whilst the person with diabetes is unconscious/sedated.

Alternatives to CSII

Individually calculated dose of long-acting insulin analogue.

Nothing

Harm from hospital acquired DKA and is not a viable