Liquid doses in mL for oral medications have been covered in Chapter 4 as well as an introduction to measuring syringe volumes with the 3-mL and the 5-mL syringe. Sufficient drawings and practice will be offered in this chapter so that syringe volume measurements for any syringes can be identified for providing the nearest measurable dose.

Examining and handling a variety of syringes and needles in the laboratory will be necessary to obtain a more comprehensive view and competence in the use of the equipment.

ESSENTIAL Vocabulary

Hypodermic General term used to describe injectables under the skin.

Insulin Syringe Small syringe, with a 0.3- to 1-mL capacity, calibrated for specific insulin mixtures in standardized units.

Intradermal (ID) Shallow injection to be given just under the skin between the dermis and the epidermis. Used mainly for skin tests. Not used to deliver medications. 0.1 mL is the usual volume for skin test injections. A 1-mL syringe is used.

Intramuscular (IM) Into the muscle. The muscle is able to accept more irritating substances than other injectable routes.

Intravenous (IV) Into the vein. These injections provide instant drug access to the circulation.

Needle Gauge Diameter (thickness) of the needle shaft. The lower the gauge number, the larger the diameter of the needle. An 18-gauge needle is much larger than a 27-gauge needle.

Parenteral Medications Injectable medications. Excludes oral, nasogastric, gastric, topical, and intestinal routes.

Prefilled Syringe Syringe prefilled by manufacturer or pharmacy with specific frequently ordered doses of medication. This method is thought to reduce dose measurement errors.

Safety Syringe Syringe designed with a variety of locking sheath covers to protect needle sterility and prevent accidental injury during and after disposal.

Subcutaneous Under the skin into the fatty layer. Used for less irritating substances than are intramuscular injections. Insulin and heparin are given subcutaneously.

Syringe Holder Specially designed device to be used only with an inserted prefilled medication cartridge.

Tuberculin Syringe Small-volume syringe, with a 1-mL capacity, used for intradermal skin tests and small-volume injections in frail at-risk populations.

Viscosity Ability to flow; thickness of a solution. A solution that is viscous may have directions for dilution. Blood is viscous, as are some reconstituted medications. Viscous solutions require larger-gauge needles. Refer to needle gauge above.

RAPID PRACTICE 6-1 Vocabulary Review

Estimated completion time: 5-10 minutes Answers on page 512

Directions: Review the vocabulary list and fill in the definitions with one- or two-word phrases.

1. The marked lines on a syringe that indicate the capacity are called ____________.

2. The route that is used for skin tests is called ________________, and the syringe used for that route has a _______-mL capacity.

3. Injectable medications are given through various routes called ________________, as opposed to the oral route.

4. The size of a needle diameter is called ____________.

5. Do needles that have a larger gauge number have a larger or smaller diameter? _____________

Syringe Sizes

20-mL, 10-mL, 5-mL, 3-mL, and 1-mL syringes

Syringes are available in many sizes, ranging from 0.3-mL insulin syringe to 60-mL or greater capacity. The decision to use a specific syringe is based on the volume of medication to be administered and the route of administration.

The 3-mL and 5-mL syringes were introduced in Chapter 5 for oral liquid medications.

Some intravenous medications may be given with large volume syringes (Figures 6-1 and 6-2).

FIGURE 6-1 20-mL syringe with 1-mL calibrations.

Intramuscular and intravenous injections may be given with a 5-mL syringe. It is used for doses of 5 mL or less (Figure 6-3)

FIGURE 6-3 5-mL syringe with 0.2-mL calibrations.

Many subcutaneous, intramuscular, and intravenous injections are given with a 3-mL syringe, used for doses of 3 mL or less (Figure 6-4).

FIGURE 6-4 3-mL syringe with 0.1-mL calibrations.

A 1-mL syringe is used for skin tests and some vaccines and may be used for infants’ injections and for very small doses. It is selected for doses of 1 mL or less (Figure 6-5).

FIGURE 6-5 1-mL tuberculin syringe with 0.01-mL calibrations.

Be sure you can identify the lowest measurable dose on each of the following syringes.

Insulin syringes

Insulin syringes are sized in 100 units, 50 units, and 30 units (Figure 6-6).

A 100-unit insulin syringe is selected for insulin doses up to 100 units.

A 50-unit insulin syringe is selected for better visualization of insulin doses up to 50 units. A 30-unit insulin syringe is selected for better visualization of insulin doses up to 30 units.

Do not use insulin syringes for anything but insulin. Insulin doses are ordered in units. Avoid confusing insulin syringes with tuberculin syringes.

All used needles as well as their attached used syringes must be placed in hazardous waste sharps containers immediately after use. They may not be thrown in trash baskets.

Do not confuse 1-mL syringes or tuberculin syringes marked in milliliters (or cubic centimeters) with 1-mL insulin syringes, which are marked with the word insulin and calibrated in units (Figure 6-7).

FIGURE 6-7 A, 1-mL tuberculin syringe. B, 100-Unit 1-mL insulin syringe. (From Potter PA, Perry AG: *Fundamentals of nursing,* ed. 7, St. Louis, 2009, Mosby.)

Do not substitute a tuberculin syringe for insulin.

Parts of the Syringe

Figure 6-8 shows the parts of a syringe. Syringes are supplied without needles or with attached needles. Supervised clinical practice is required in order to learn safe handling of syringes and needles.