ADVANCING YOUR PRACTICE

Understanding insulin pumps

People with diabetes can use insulin pumps to help manage their insulin and blood glucose levels. By wearing a small external device, patients get continuous subcutaneous insulin infusion through a catheter placed under the skin. Insulin pumps deliver rapid- or short-acting insulin around the clock.

Skin deep
An insulin pump consists of a 3-mL syringe attached to a long (24- to 42-inch), thin, narrow tube with a needle or Teflon catheter attached to the end. The patient inserts the needle or catheter into subcutaneous tissue (usually on the abdomen) and secures it with tape or a transparent dressing. The needle or catheter is changed at least every 3 days. The patient then wears the pump either on a belt or in a pocket. Some women keep the pump tucked into the front or side of their bra or wear it on a garter belt on the thigh.

The insulin pump delivers insulin by subcutaneous infusion at a basal rate, such as 0.5 to 2 units per hour. When the patient eats a meal, he calculates the insulin dose needed to metabolize the meal and administers a bolus. He counts the total amount of carbohydrate for the meal using a predetermined insulin-to-carbohydrate ratio; for example, a ratio of 1 unit of insulin for every 15 grams of carbohydrate would require 3 units of insulin for a meal with 45 grams of carbohydrate. This allows for flexibility in food choices and meal times.

Possible problems
A disadvantage of insulin pumps is an increased risk of diabetic ketoacidosis caused by unexpected disruptions of insulin flow from the pump. These may be due to occluded tubing or needle, insulin supply running out, or depletion of the battery. Because only rapid-acting insulin is used in the pump, any interruption in the flow of insulin may rapidly cause the patient to be without insulin. The patient should be taught to administer insulin by manual injection if an insulin interruption is suspected. Effective patient teaching minimizes this risk; teach your patient the basics of how to use the pump and what to do if complications arise.

Hypoglycemia may also occur with insulin pump therapy, but usually because patients are able to achieve lower blood glucose levels, not because of specific problems with the pump.

Another disadvantage is the potential for infection at needle insertion sites. Some patients find that wearing an insulin pump 24 hours a day is inconvenient. However, the pump can easily be disconnected, per patient preference, for limited periods, such as for showering, exercise, or sexual activity.

Candidates for the insulin pump must be willing to assess their blood glucose level several times daily. In addition, they must be psychologically stable and open about having diabetes, because the insulin pump is often visible to others and a constant reminder to patients that they have diabetes. Most important, patients using insulin pumps must have extensive education in the use of the pump and in self-management of blood glucose and insulin doses. They must work closely with a team of healthcare professionals who are experienced in insulin pump therapy, specifically a diabetologist/endocrinologist, a dietitian, and a certified diabetes educator.

Many insurance policies cover the cost of insulin pump therapy. If not, the extra expense of the pump and associated supplies may be a deterrent for some patients.

Selected references
American Diabetes Association. Insulin pumps. http://www.diabetes.org/type-1-diabetes/insulin-pumps.jsp.
Melville B. The insulin pump: Why not use it for every type I diabetic patient? Critical Care Nursing Quarterly. 28(4):370-377, October-December 2005.
Smeltzer SC, et al. Brunner & Suddarth's Textbook of Medical-Surgical Nursing, 11th edition. Philadelphia, Pa., Lippincott Williams & Wilkins, 2007.
Webb KE. Use of insulin pumps for diabetes management. Medsurg Nursing. 15(2):61-68, April 2006.
White RD. Insulin pump therapy (continuous subcutaneous insulin infusion). Primary Care. 34(4):845–871, December 2007.

Source: LPN2008. March/April 2008.