When a person uses an insulin pump to control his diabetes, one of the decisions he has to make is what model of infusion set to use. Pumps are often an excellent choice for people who use insulin and seek tight control of their diabetes but need some flexibility in their diabetes regimen.
Most insulin pumps require the use of an infusion set to deliver insulin from the pump to the user. An infusion set consists of a length of thin plastic tubing, a very thin stainless steel or Teflon cannula that is inserted just under the skin, and a plastic connector that joins tubing and cannula together. The connector is generally mounted on an adhesive patch that is stuck to the skin at the insertion site to help keep the cannula in place. The connector allows a person to disconnect from his pump temporarily (for swimming, intimate situations, etc.) without removing the infusion set.
Insulin infusion sets come in a variety of styles to suit individuals’ unique needs and preferences. In addition to having either a Teflon or steel cannula, infusion sets may be designed to have the cannula inserted straight into the subcutaneous tissue or at an angle. Some cannulas can only be inserted manually, while others can be inserted either manually or with an insertion device. All infusion sets offer a variety of tubing lengths.
Teflon versus steel cannula
A “soft” cannula is a thin, flexible needle made of the synthetic substance Teflon that is inserted into the subcutaneous tissue via a steel introducer needle. The introducer needle is then removed and only the soft cannula is left in place. Soft cannula sets are popular because they are comfortable to wear and they can remain inserted for up to 72 hours. One disadvantage of the soft cannula, however, is that its flexibility can potentially lead to kinking, which disrupts the flow of insulin into the body. If a disruption is not detected, it can lead to dangerously high blood glucose levels. Users of soft cannulas, therefore, need to know how to troubleshoot and immediately change their infusion sets if kinking occurs.
A steel cannula is a thin metal needle that is inserted into the subcutaneous tissue; steel cannulas should stay in place for no longer than 48 hours. One advantage of using a metal cannula is that it is durable and will not kink, assuring a continuous flow of insulin into the body. Metal cannulas are also very useful for people who are allergic to Teflon. The disadvantages of using a metal cannula are that it can cause discomfort during movement or physical activity and that it requires more frequent site changes.
Method of insertion
There are two options for inserting a cannula. A person can choose manual insertion, which means that he simply pushes the needle into his subcutaneous tissue as if giving himself an injection, or he can use a spring-loaded insertion device that automatically inserts the needle into the tissue. The manual method is useful for people who like to control the speed of the insertion; it allows them to prepare themselves psychologically for the task and to achieve a gradual and less forceful insertion. People who are lean often prefer manual insertion.
Many people, however, prefer using an insertion device. These devices are definitely helpful for people who have arthritis, Parkinson disease, or any other condition that affects fine motor skills, as well as for people who have a needle phobia. Insertion devices also allow the pump user to insert a cannula more easily into harder-to-reach infusion sites, such as the buttocks or the back of the arm. The disadvantages of using an insertion device include the added expense (though it is usually covered by insurance, and some devices are reusable) and the additional education needed to learn to use it correctly. Another disadvantage is that the user cannot control the depth or the exact angle of insertion.