Infusion set

An infusion set is used with an insulin pump as part of intensive insulin therapy. The purpose of an infusion set is to deliver insulin under the skin. It is a complete tubing system to connect an insulin pump to the pump user: it includes a subcutaneous cannula, adhesive mount, quick-disconnect, and a pump cartridge connector.

Firstly, the user must attach a reservoir of insulin to the set and connect it to the pump. The set is then "primed" - the pump pushes insulin quickly through the tubing and the cannula to ensure no air is in the system before insertion. Note that it is vital that the infusion set is not inserted into the skin when the set is being primed (as this could result in the accidental delivery of a large dose of insulin). The user then peels off the paper protecting the adhesive pad and carefully inserts the needle beneath the skin.

The cannula is usually made of flexible plastic, which allows it to move without causing discomfort to the patient. The needle is pushed into the layer of fat below the skin, taking the plastic cannula with it. The needle is then removed, leaving the cannula in place below the skin. Insertion should be done in a fairly swift movement to avoid the cannula "bunching up" around the needle.

A few pump users prefer an infusion set with a steel needle instead of a cannula. The cannula surrounds a steel needle similar to that found on a hypodermic syringe.

The same used device can't be reused for the other patient, even if the set is washed or re-sterile. As it is not a surgical instrument. It is for single use only.

Some pump users prefer to use an insertion device to insert their sets, rather than pushing the needle in by hand. These are spring-loaded and are designed to push the needle into the skin quickly and (usually) painlessly. The user simply loads the primed set into the insertion device, peels off the paper protecting the adhesive pad, places the device against the skin and presses a button. This may be an advantage for those with needle phobia.

Many pump users site their infusion sets on the abdomen, in a roughly semicircular area around and below the navel. Other sites include the upper leg, upper buttocks, hips, upper arms and lower back. Insulin absorption may vary from site to site, so it is important that patients are advised of the most effective sites to use by their diabetes adviser.

The infusion set must be replaced regularly, usually every 2–3 days. Insulin absorption becomes less effective the longer the set is left in place, leading to poorer control of blood glucose. For this reason, the site of the infusion set is moved when the set is changed. Often a number of favorite sites for the infusion set are used on a rotation basis.

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Wikipedia