Medication Administration: Intramuscular Injections
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Intramuscular (IM) injections have been associated with adverse effects and pain, and this route of medication injection should be used as a last resort. Consider contacting the practitioner for an alternative, preferred route of medication administration.
Take extra care with a patient who takes medications that increase the risk for bleeding.undefined#ref4">4
Take steps to eliminate interruptions and distractions during medication preparation.
The IM injection route deposits medication into deep muscle tissue, which has a rich blood supply, allowing medication to be absorbed faster than it would be by the subcutaneous route. This rich blood supply, however, increases the risk for injecting drugs directly into blood vessels. Any factor that interferes with local tissue blood flow affects the rate and extent of drug absorption.
An IM injection may require a longer and larger-gauge needle to penetrate deep muscle tissue. The needle is inserted at a 90-degree angle; this varies from the angle used for subcutaneous and intradermal injections (Figure 1).2,5 The appropriate needle length is determined by the patient’s age and weight, injection site, and the amount of adipose tissue in the chosen injection site.2,7 The needle must be long enough to reach the muscle tissue but not too long to present the risk of hitting underlying neurovascular structures or bone.2
IM injections should be administered with the needle perpendicular to the patient’s body or as close to a 90-degree angle as possible.2,5 IM injection sites should be rotated to decrease the risk for hypertrophy. When possible, IM injections should not be administered in muscles that are emaciated or atrophied because they absorb medication poorly.5
Aspiration before injection and slow injection of the medication are not required for vaccine administration.2 The vastus lateralis and deltoid muscle are the only two sites recommended for vaccine administration because they do not contain large vessels that are within reach of the needle.2 For all other medications there is no evidence to support abandoning the practice of aspiration before administration. More research is needed to investigate the practice of aspiration before administering an IM injection with medications other than vaccines.9 The recommended route and site for each vaccine is included in the manufacturer’s instructions for use.10
Muscle tissue is less sensitive than subcutaneous tissue to irritating and viscous medications. Small muscles absorb small volumes. For a well-developed adult, no more than 3 ml of medication should be administered in a single IM injection because the muscle tissue does not absorb it well in larger volumes.5,8 For smaller adults or those with less muscle mass, the volume injected may need to be adjusted. There may be exceptions for specific medications. Refer to the organization’s formulary.
The Z-track method (pulling the skin laterally before injection) can be used if the overlying tissue can be displaced. This technique prevents medication leakage into subcutaneous tissue, seals medication in the muscle, and minimizes irritation.5 To use the Z-track method in an adult, the appropriate-size needle is attached to the syringe, and an IM site is selected. The overlying skin and subcutaneous tissues are pulled to the side with the ulnar side of the nondominant hand. The skin is held in this position until the injection has been administered. After the site is cleansed, the needle is injected deep into the muscle, and the medication is injected slowly. After the needle is withdrawn, the skin is released. The displacement of the skin and muscle layer closes off the needle track when the skin is released (Figure 2). The Z-track method should not be used with infant vaccinations where skin is compressed.
For IM injections, the nurse selects a site that is free of pain, infection, necrosis, bruising, and abrasions. The location of underlying bones, nerves, and blood vessels and the volume of medication to be administered are also considered. Because of the sciatic nerve location, the dorsogluteal muscle is not recommended as an injection site. If a needle hits the sciatic nerve, the patient may experience partial or permanent paralysis of the leg.5,8 The rectus femoris is no longer considered a safe injection site because of the risk of damage to the descending branch of the lateral circumflex femoral artery and the muscle branch of the femoral nerve to the vastus lateralis.6
The ventrogluteal site involves the gluteus medius and minimus muscles and is a safe injection site for adults, children, and infants.5 This site provides the greatest thickness of gluteal muscle that is free of penetrating nerves and blood vessels and it has a narrower layer of fat.5,8 The ventrogluteal site should be used with caution in infants.1 It is recommended that only an experienced pediatric health care team member use this site.
To locate the ventrogluteal site, the heel of the hand is placed over the greater trochanter of the patient’s hip with the wrist almost perpendicular to the femur. The right hand is used for the left hip, and the left hand is used for the right hip. The thumb is pointed toward the patient’s groin, with the index finger pointing to the anterior superior iliac spine, and the middle finger is extended back along the iliac crest toward the patient’s buttock. The index finger, the middle finger, and the iliac crest form a V-shaped triangle, with the injection site at the center of it (Figure 3). To relax this muscle site, the patient should lie flat and supine and flex the knee and hip, or the patient may lie on the side.
The vastus lateralis muscle is another injection site used in adults, children, and infants.5 The muscle is thick and well developed, and it is located on the anterior lateral aspect of the thigh. In an adult, the vastus lateralis extends from just above the knee to just below the greater trochanter of the femur (Figure 4). The middle third of the muscle is used for the IM injection site. To help relax this muscle site, the patient should lie flat, supine, flex the knee slightly, and externally rotate the foot, or the patient may assume a sitting position.
The deltoid site is easily accessible in many adults, but the muscle tends to be underdeveloped, which causes a potential for injury because the axillary, radial, brachial, and ulnar nerves and the brachial artery lie within the upper arm (Figure 5). This site can be used for small medication volumes (2 ml or less)5,8 and for administration of routine immunizations in children older than 3 years2,5 and adults with acceptable muscle mass and development, and when other sites are inaccessible because of dressings or casts.2
The deltoid muscle is located by fully exposing the patient’s upper arm and shoulder and asking the patient to relax the arm at the side or by supporting the patient’s arm and flexing the elbow. The lower edge of the acromion process, which forms the base of a triangle in line with the midpoint of the lateral aspect of the upper arm, is palpated, and the injection site is found in the center of the triangle (Figure 5).
To avoid shoulder injury related to vaccine administration, the nurse should always sit to inject into the arm of a seated patient to ensure that the angle of the needle is correct. If the patient’s shirt cannot be removed, the sleeve should be rolled up, so that landmarks can be visualized and used appropriately.4
Rarely, an adverse reaction occurs after immunizations. Reactions may include anaphylaxis, anaphylactic shock, and neurologic deficits.10 Vaccine adverse event reporting is monitored by the Centers for Disease Control and Prevention.
If the patient expresses concern regarding the accuracy of a medication, the medication should not be given. The patient’s concern should be explored, the practitioner notified, and the order verified.
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Do not use medication that is cloudy or precipitated unless such is indicated by its manufacturer as being safe.
Medications or other solutions in unlabeled containers are unidentifiable. Errors, sometimes tragic, have resulted from medications and other solutions removed from their original containers and placed into unlabeled containers. This unsafe practice neglects basic principles of medication management safety, yet has been routine in many organizations.4
Rationale: A comfortable position reduces strain on the muscle and minimizes injection discomfort.
Rationale: Injection sites should be free of abnormalities that interfere with drug absorption (e.g., bruising, signs associated with infection).
Rationale: Sites used repeatedly become hardened from lipohypertrophy (increased growth in fatty tissue).
Rationale: Injection into the correct anatomic site prevents injury to nerves, bone, and blood vessels.
The dorsogluteal site is not recommended because of proximity to the sciatic nerve.5,8
Rationale: A vapocoolant spray decreases pain at the injection site.
Rationale: The swab or gauze remains readily accessible for use when withdrawing the needle.
Rationale: Pulling the cap straight off prevents the needle from touching the sides of the cap, thus preventing contamination.
Rationale: A quick, smooth injection requires proper manipulation of the syringe parts.
Rationale: The Z-track technique creates a zigzag path through tissues that seals the needle track to avoid tracking medication. A quick, dart-like injection reduces discomfort. Z-track injections may be used for all IM injections.5,8
Rationale: Smooth manipulation of the syringe reduces discomfort from needle movement. Skin remains pulled until after the medication is injected to ensure Z-track administration.
Rationale: Grasping the muscle body helps ensure that the medication reaches the muscle mass.
Rationale: Aspiration of blood into the syringe indicates possible placement into a vein.
Rationale: There is no definitive research to recommend eliminating aspiration other than for vaccination and toxoids.5,8
Rationale: Grasping the muscle body helps to ensure that the medication reaches the muscle mass.
Rationale: Massage damages underlying tissue.
Rationale: Discarding the uncapped needle helps prevent injury to the patient and health care team members. Recapping needles increases the risk for a needlestick injury.7
Centers for Disease Control and Prevention (CDC). (2018). Vaccine administration. Retrieved February 11, 2023, from https://www.cdc.gov/vaccines/hcp/admin/admin-protocols.html
Kroger, A., Bahta, L., Hunter, P. (2023). Vaccine recommendations and guidelines of the ACIP: General best practice guidelines for immunization. Retrieved February 11, 2023, from https://www.cdc.gov/vaccines/hcp/acip-recs/general-recs/index.html
U.S. Food and Drug Administration (FDA). (2021). Safely using sharps (needles and syringes) at home, at work and on travel. Retrieved February 11, 2023, from http://www.fda.gov/medicaldevices/productsandmedicalprocedures/homehealthandconsumer/consumerproducts/sharps/default.htm
*In these skills, a “classic” reference is a widely cited, standard work of established excellence that significantly affects current practice and may also represent the foundational research for practice.
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