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. |