Syringe and Needle Health Article

Definition

Syringes and needles are sterile devices used to inject solutions into or withdraw secretions from the body. The syringe is a calibrated glass or plastic cylinder with a plunger at one and an opening to which the needle attaches.

Purpose

This method is used to administer drugs when a small amount of fluid is to be injected, the patient is unable to take the drug orally, or intestinal secretions destroy the drug. It is also to withdraw various types of bodily fluids, most commonly blood.

Description

There are different types and sizes of syringes used for a variety of purposes. Syringe sizes may vary from0.25 ml to 450 ml, and can be made from glass or assorted plastics. Latex-free syringes eliminate the exposure of the health care professional and the patient to an allergen to which he or she may be sensitive. The most common type of syringe is the piston syringe. The pen, cartridge, and dispensing syringes are also extensively used.

A syringe consists of a hollow barrel with a piston at one end and a nozzle at the other end that connects to a needle. Other syringes have a needle already attached. These devices are often used for subcutaneous injections of insulin and are single-use (i.e., disposable). Syringes have markings etched or printed on their sides, showing the graduations (i.e., in milliliters) for accurate dispensing of drugs or removal of body fluids. Cartridge syringes are for multiple use, and are often sold in kits where a prefilled drug cartridge with a needle is inserted into the piston syringe. Syringes may also have antineedlestick features, as well as positive stops that prevent accidental pullouts.

There are three types of nozzles:

• Luer-lock, which locks the needle onto the nozzle of the syringe.
• Slip tip, which secures the needle by compressing the hub onto the syringe nozzle.
• Eccentric, which secures with a connection that is almost flush with the side of the syringe.

The hypodermic needle is a hollow, metal tube, usually made of stainless steel and sharpened at one end. It has a female connector end that fits into the male connector of a syringe or intravascular administration set.

The size of the diameter of the needle ranges from the largest gauge (13) to the smallest (27). The needle's length extends to 3.5 inches (8 cm) for the 13 gauge, and from 0.25–1 inch (0.6-2.5 cm) for the 27 gauge. The needle consists of a hub with a female connector at one end—that connects to a syringe—to the other end, where the bevel is located. The bevel is a flat aperture on one side of a needle's tip.

Needles are almost always disposable, but reusable ones are available for home use by a single patient.