Hypodermic needles are used to inject medications in patients for their care or treatment. Choosing the right needle is not always an easy task as modern hypodermic needles come in many sizes and designs. The main system to measuring hypodermic needles diameter is the Birmingham gauge.
- Regular standard sizes for general use are usually thinner needles (within a range which goes from 27G up to 23G);
- For oil based solutions, serums aspirating and other applications standard needles go up to a wider gauge (from 22G to 16G).
The needle and site selection depends mainly on the kind of injection the patient has to receive.
The intradermal injection is given in the dermis on a 90° angle. Specifically, the recommended injection sites for intramuscular injections are the deltoid arm muscle, the vastus lateralis thigh muscle for adults, the ventrogluteal site for children from 18 months to 18 years old, and the vastus lateralis thigh muscle for infants younger than 18 months.
The subcutaneous injection is given in the subcutaneous tissue on a 45° to 90° angle. The recommended injection sites for subcutaneous injections are the anterolateral thigh, upper outer tricep area, upper buttocks, and abdomen.
The intramuscular injection is directly administered into the muscle on a 10° to 15° angle. The recommended injection sites are the anterior aspect of forearm, the upper chest, the upper back, and the back of upper arm.
- Precise angle design reduces pain & damage to vessel;
- Homogeneous use of silicon minimizes the knocking effect during placement;
- Ultra-thin wall results in easy and fast administration of viscose fluids;
- Standard needle bevel results in a less painful usage.
Caution should be used when handling needles and syringes to avoid autoinoculation and the transmission of illnesses during use and disposal. After use, needles should be promptly disposed in a sharps container.
Exposure from needles has been reported when used syringes are not collected in the proper way. Needles should not be bent, shared, replaced in the needle sheath or guard, or removed from the syringe after being used. Sharp containers must be disposed carefully.
Detachable needles are used for luer lock syringes. They work by having a twist fit thread around the tip of the syringe, in order for the needle to screw down and be sealed in a safer way, making it leak-free as well. Usually detachable needles have two small tabs on the outside that fit into this thread, in order to be fitted to luer lock syringes.
Detachable needles are also used for luer slip syringes, the most commonly used device being the luer slip type. The luer slip is, as the luer lock, based on a leak-free connection between a needle, which slips into the syringe. The needle is fixed into the syringe by simply pushing it. Although it is only fixed through friction, as there is no thread, the seal is still safe.