The parenteral route is where medication is injected into the patient using a syringe. There are four commonly used parenteral routes: intradermal (ID), subcutaneous (SC), intramuscular (IM), and intravenous (IV).
The choice of which of the parenteral routes to use is determined by the prescriber based on the nature of the medication, the desired onset of the therapeutic effect, and the patient’s needs. For example, the test for TB is per-formed by injecting the purified protein derivative intradermally, which is under the skin. Insulin is injected subcutaneously, although regular insulin can also be administered intravenous. Medications administered intravenously have a faster onset of therapeutic effect than other parenteral routes. Vacci-nations, some antibiotics, and other medications are injected intramuscularly.
INTRADERMAL
Intradermal injections are given in hairless areas of the body that are lightly pig-mented and thinly keratinized so that the nurse can observe any reaction to the medication. These are:
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Inner aspect of forearm or scapular area of back.•
Upper chest.•
Medial thigh sites.Medication injected intradermally has a localized effect because it does not enter the bloodstream. It usually causes a wheal (blister) to appear at the injection site. Injections are given using a 26–27 gauge needle and a 1 mL syringe calibrated in 0.01 mL increments. The typical injection is between 0.01 to 0.1 mL.
Here’s how to administer medication intradermally:
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Check the prescriber’s medication order.•
Wash hands and then put on clean gloves.•
Properly identify the patient.•
Cleanse the area of the site in a circular motion using alcohol or betadine, depending on the medication and agency policy.•
Hold the skin taut.•
Position the bevel up and insert the needle at a 10- to 15-degree angle. You should be able to see the outline of the needle through the skin.•
Inject slowly to form a wheal.•
Slowly remove the needle.•
Don’t massage the area.•
Mark the site with a pen.•
Tell the patient not to wash the mark until a healthcare provider assesses the site for a reaction between 24 to 72 hours after the injection.•
Assess the patient in 24 to 72 hours. If the patient is allergic to the med-ication, then the diameter of the wheal should increase. If the patient is tested for TB, assess the hardness of the wheal and not the redness of the area.SUBCUTANEOUS
The subcutaneous injection is suited for medications that need to be absorbed slowly to produce a sustained effect, such as insulin and heparin. Subcutaneous medications are absorbed through capillaries and the onset of the medication is slower than intramuscular and intravenous routes.
Choose an injection site that has an adequate fatpad. To prevent lypodystro-phy, sites must be rotated if injections are given frequently. Lypodystrophy is a loss of the fat area under the skin causing ineffective absorption of insulin.
These sites are: abdomen, upper hips, upper back, lateral upper arms, and lateral thighs.
Subcutaneous injections are given using a 25–27-gauge needle that is 1/2or
5/8inches in length and with a 1 to 3 mL syringe calibrated 0.5 to 1.5 mL. How-ever, syringes used for insulin are measured in units and not mL.
Here’s how to administer medication subcutaneously:
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Check the prescriber’s medication order.•
Wash hands and then put on clean gloves.•
Properly identify the patient.•
Cleanse the area of the site in a circular motion using alcohol, betadine, or soap and water as per agency policy.•
Pinch the skin.•
Insert the needle at 45–90-degree angle. 45 degree is preferred when the patient has a small amount of subcutaneous tissue.•
Release the skin.•
Inject the medication slowly.•
Quickly remove the needle.•
Gently massage the area unless heparin is injected.•
Apply a band aid as necessary.INTRAMUSCULAR
Intramuscular injections are used so that the medication is rapidly absorbed into the patient’s body. The absorption rate depends on the patient’s circulatory state.
Usually no more than 5 mL of medication is injected for an adult and 3 mL for a child. If the prescriber orders a higher dose, divide the dose into two syringes.
Choose an injection site based on the size of the muscle with a minimum number of nerves and blood vessels in the area. These sites are:
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Ventrogluteal (hip)•
Dorsogluteal (buttocks)•
Deltoid (upper arm)•
Vastus lateralis (front of thigh) See Table 6-1 for more details.Intramuscular injections use a 20 to 23-gauge needle that is 1 to 1.5 inches in length and a 1 to 3 mL syringe that is calibrated with 0.5 mL to 1.5 mL.
Here’s how to administer medication intramuscularly:
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Check the prescriber’s medication order.•
Wash hands and then put on clean gloves.•
Properly identify the patient.•
Cleanse the area of the site in a circular motion, using using alcohol or betadine as per the agency guidelines.•
Flatten the skin at the injection site using your thumb and index finger.•
Insert the needle at a 90-degree angle into the muscle between your thumb and index finger.•
Release the skin.•
Slowly inject the medication.•
Quickly remove the needle.•
Gently massage the area (unless this is contraindicated by the medication).Z-Track Injection Technique
The Z-Track inject technique is used to prevent medication from leaking back in the subcutaneous tissue after the medication has been injected into the patient.
This technique is used whenever the medication—such as dextran (iron)—might cause a visible and permanent skin discoloration. The gluteal muscle is the pre-ferred site for a Z-Track injection.
Here’s how to administer medication using the Z-Track technique:
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Check the prescriber’s medication order.•
Wash hands and then put on clean gloves.Injection Site Description
Ventrogluteal • Relatively free of major nerves and vascular branches.
• Well-defined bony anatomic landmarks.
• For IM or Z-Track injections.
• Locate the site by placing the heel of your hand on the greater trochanter of the femur with the thumb pointed toward the umbilicus. The index finger marks the anterosuperior iliac spine.
The middle finger traces the iliac crest curvature.
The space between the index and middle fingers is the injection site.
Dorsogluteal • Good site for IM and Z-track injections.
• Danger to major nerves and vascular structures near site.
• Easy to give subcutaneously by mistake when trying to give an IM because the fat is often very thick.
Deltoid • Preferred site for vaccines.
• Easily accessible.
• Muscle mass is small compared to other sites.
• Use a 5/8inch to 1.5 inch long needle
• Locate the acromion process of the scapula and the deltoid. Measure 2 to 3 fingers below the acromion process on the lateral midline of the arm to identify the proper site. Inject at a 90-degree angle.
Vastus lateralis • Preferred site for infants younger than 7 months.
• It has a relatively large muscle mass.
• Free from major nerves and vascular branches.
• Site is a hand’s breadth below the greater trochanter and above the knee.
• Inject at a 45-degree angle toward the knee.
Table 6-1. Injection sites.