Syringes: Parts, Calibration, and Types

Syringes

• The user should locate and label the parts of a syringe in their kit

Syringe Parts

• The barrel holds the medication and has calibrations for measuring the quantity
• The plunger is an inner solid rod
• Pulling back on the plunger allows solution to enter the barrel
• Pushing the plunger ejects air or medication
• The tip is the end of the barrel where the needle attaches
• Most syringes have Luer Lock versions that secure the needle

Syringe Calibrations

• Syringes can be calibrated in cc, mL, units, and sometimes minims (apothecary)

Syringe Types and Uses

• Hypodermic syringes come in 1 mL and 3-5 mL sizes
  • They are for intramuscular (IM), intravenous (IV), and subcutaneous (SQ/Subcut) injections
• Hypodermic syringes in 10, 20, and 60 mL sizes are for irrigation, IV medications, intradermal (ID), allergy testing, and Heparin
• Tuberculin syringes are 1 mL, titrated to 0.1 mL increments or 16 minims
• Insulin syringes are available in standard sizes

Standard Insulin Syringes

• 1. 0 mL syringes are for doses over 50 insulin units and numbered at 2-unit intervals
• 0. 5 mL syringes are for 30 to 50 insulin units and numbered at 1-unit intervals
• 0. 3 mL syringes are for doses under 30 insulin units and numbered at 1/2-unit or 1-unit intervals
• Prefilled cartridges are used with a carpuject

Needles

• The shaft is a hollow tube that delivers medication, its length depends on the depth that medication will reach
• The lumen is the oval-shaped opening at the needle's end
• The tip is the sharpened end of the needle
• The bevel is a flat, slanted surface on the point
• The hub connects the needle to the syringe
• The gauge is determined by the lumen's diameter, ranging from 16gu to 30gu
  • Larger numbers indicate a thinner needle and smaller diameter

Needle Length by Injection Type

• ID (tuberculin injection): 25-27gu needle, 3/8 in - 1/2 in - 5/8 in length
• Subcutaneous injection (non-insulin): 25-29gu needle, 3/8 in - 1/2 in - 5/8 in length
• Subcutaneous injection (insulin): 25-29gu needle, 3/8 in - 1/2 in - 5/8 in length, or 30-31 gu insulin pen needles
• Use a filter needle/straw when withdrawing from a glass ampule
  • The needle should be at least 1 inch long
• IM Injections: 20-23 gu
  • Some sources say 18-25 gu
  • Typical IM injections use a 20-23 gauge needle
  • Length: 1-1 1/2 inches (up to 3 inches for larger patients)
• Site selection depends on factors like the injection site, the person's age and size, muscle and fat mass, medication volume, and viscosity

Additional Information

• Adult IM injections into subcutaneous tissue: requires a needle length of 1-1 1/2 inches or greater depending on amount
• Never recap dirty needles to protect person administering the injection
  • See Needle Safety Notes for more information
• If it is necessary to recap a clean needle, use the one-handed scoop technique

Learn about the different parts of a syringe, including the barrel, plunger, and tip. Understand syringe calibrations in cc, mL, and units. Identify various syringe types like hypodermic, tuberculin, and insulin syringes, and their specific uses for injections and medications.