How to manage insulin for a patient on an insulin pump (Continuous Subcutaneous Insulin Infusion) requiring Total Parenteral Nutrition (TPN)?

Management of Insulin for Patients on Insulin Pump Requiring TPN

For patients on insulin pumps (CSII) requiring Total Parenteral Nutrition (TPN), the insulin pump should be disconnected and a basal-bolus insulin regimen initiated with regular insulin added directly to the TPN solution at a starting dose of 1 unit per 10g of carbohydrate in the TPN. 1

Initial Assessment and Setup

• Disconnect the insulin pump when initiating TPN therapy, as pump therapy is not appropriate during periods requiring TPN 1
• Initiate a basal-bolus subcutaneous insulin regimen based on the patient's previous total daily dose (TDD) from the pump (available from the pump menu) 1
• For the TPN component, add regular insulin directly to the TPN solution at a starting dose of 1 unit per 10g of carbohydrate 1
• Monitor blood glucose every 4-6 hours and adjust insulin doses accordingly 1

Specific Insulin Management Protocol

For the TPN Component:

• Add regular human insulin to the TPN solution at an initial dose of 1 unit per 10g of carbohydrate 1
• Adjust the insulin dose daily based on blood glucose monitoring results 1
• If more than 20 units of correctional insulin have been required in the past 24 hours, increase the amount of insulin added to the TPN solution 1

For Basal Coverage:

• Calculate the patient's 24-hour basal insulin requirement from the pump settings 1
• Administer this as subcutaneous long-acting insulin (glargine or detemir) in 1-2 daily doses 1
• If previous basal rates are unknown, start with 5 units NPH/detemir every 12 hours or 10 units glargine daily 1

For Correctional Coverage:

• Provide subcutaneous correctional insulin using regular insulin every 6 hours or rapid-acting insulin every 4 hours for hyperglycemia 1
• Develop a patient-specific correction scale based on insulin sensitivity 1

Special Considerations

• If TPN is interrupted, immediately start a 10% dextrose infusion to prevent hypoglycemia 1
• Ensure blood glucose targets remain between 140-180 mg/dL (7.8-10.0 mmol/L) during TPN therapy 1
• Be vigilant for insulin adsorption to the TPN bag material, which may reduce insulin bioavailability (44-95% depending on bag material) 2, 3
• Constant infusion rates for TPN are essential to minimize the risk of hypoglycemia or hyperglycemia 4

Transitioning Back to Insulin Pump

• The insulin pump can be reconnected once the patient is clinically stable, eating normally, and able to manage the pump independently 1
• Start the pump at least 1-2 hours before discontinuing TPN and any IV insulin 1
• Monitor blood glucose closely during the transition period 1

Potential Complications and Management

• Hypoglycemia: If TPN is interrupted, immediately start 10% dextrose infusion 1
• Hyperglycemia: Increase insulin in TPN solution and/or correctional insulin doses 1
• Ketoacidosis: Monitor for ketosis if blood glucose exceeds 16.5 mmol/L (300 mg/dL), especially in type 1 diabetes 1

This approach ensures appropriate glycemic control while maintaining patient safety during the period requiring TPN therapy, with clear guidelines for transitioning back to insulin pump therapy when appropriate.