Injections, IV Monitoring, Blood Products and TPN

Injection Techniques and Medication Preparation

Administering medications via the parenteral route requires careful selection of equipment and anatomical landmarks. Subcutaneous injections deliver medication into the adipose tissue at an angle of 45 to 90 degrees. Needle selection depends on the client's build and tissue depth, typically utilizing a needle ranging from 25 to 30 gauge and 3/8 to 5/8 inch in length. Common subcutaneous injection sites include the abdomen, the outer aspect of the upper arms, and the anterior thighs. When administering subcutaneous heparin and enoxaparin, the abdomen is the preferred site. To prevent localized tissue injury and hematoma formation, the nurse does not aspirate before injection and does not massage the site after administering subcutaneous heparin or enoxaparin.

Intramuscular injections deposit medication deep into muscle tissue at a 90-degree angle. For average-weight adults, needle lengths typically range from 1 to 1.5 inches to ensure penetration through subcutaneous layers into the muscle bed. The ventrogluteal muscle is the preferred intramuscular injection site for adults and walking children. For infants and young children, the vastus lateralis muscle is the preferred site. Due to the significant risk of sciatic nerve injury, the dorsogluteal site is avoided for intramuscular injections. Additionally, the deltoid muscle is generally limited to intramuscular injection volumes of 1 mL or less in adults. To seal medication within the muscle and prevent tracking into subcutaneous tissue, the nurse utilizes the Z-track technique for intramuscular injections.

Safe preparation begins with inspecting containers and handling glass ampules and vials properly. An ampule must be tapped lightly to move all medication from the neck to the body before opening. Because snapping the glass neck can create microscopic debris, a sterile filter needle must be used to withdraw medication from a glass ampule to prevent aspirating glass particles. The filter needle must then be removed and replaced with an appropriate injection needle before administering the medication. Air should never be injected into an open glass ampule. In contrast, when preparing medication from a closed vial, the rubber stopper must be cleansed with an antiseptic swab and allowed to dry before needle insertion. Air equal to the prescribed dose must then be injected into the vial above the fluid level to facilitate withdrawal.

When preparing a combined injection of regular and NPH insulin in one syringe, strict sequencing prevents contamination of the vials. First, air is injected into the NPH vial, followed by injecting air into the regular vial. When withdrawing the combined insulins into the syringe, clear regular insulin is drawn before cloudy NPH insulin. Following this precise sequence protects the fast-acting regular insulin supply from being altered by the cloudy intermediate-acting NPH insulin.