CHAPTER 24

CHAPTER 24: INTRAMUSCULAR INJECTION (IM INJECTION) – EXPLANATION 

An intramuscular (IM) injection is the process of administering medication directly into the muscle tissue. Muscles have a larger blood supply than fat tissue, allowing for quicker absorption of the medication into the bloodstream. This type of injection is commonly used when medications need to be absorbed more rapidly or when the drug is irritating to the skin or subcutaneous tissue. 

Common Sites for Intramuscular Injections 

1. Deltoid Muscle (upper arm) 

1. Location: One to two inches below the acromion (shoulder bone) at the top of the arm. 

2. Preferred for: Vaccinations and small-volume injections (usually up to 1-2 mL). 

2. Vastus Lateralis (outer thigh) 

1. Location: Midway between the knee and the hip on the outer side of the thigh. 

2. Preferred for: Infants, small children, and people who cannot tolerate injections in the deltoid. 

3. Gluteus Medius (upper outer quadrant of the buttocks) 

1. Location: Located in the upper outer quadrant of the buttock. 

2. Preferred for: Larger volumes of medication (3-5 mL) and adults. 

4. Rectus Femoris (front thigh) 

1. Location: Front of the thigh, between the hip and knee. 

2. Preferred for: Infants and toddlers, though less commonly used in adults. 

Indications for Intramuscular Injection 

• Medications: Vaccines, hormone therapies, pain relievers (e.g., morphine), vitamin B12, antibiotics, and other medications that require faster absorption. 

• Faster Absorption: IM injections are absorbed more quickly compared to subcutaneous (under the skin) injections due to the greater blood supply in muscle tissue. 

• Larger Volumes: IM is used when larger volumes of medication are needed, typically up to 5 mL. 

Procedure for Administering an Intramuscular Injection 

1. Preparation: 

1. Gather the necessary supplies: syringe, needle (appropriate size), alcohol swab, gloves, and medication. 

2. Check the medication and ensure it’s the correct dose and type. 

3. Wash hands thoroughly and put on gloves. 

2. Choosing the Injection Site: 

1. Identify the appropriate site (deltoid, vastus lateralis, or gluteus medius). 

2. For deltoid, find the acromion process (top of the shoulder), and give the injection 1-2 inches below it. 

3. For vastus lateralis, locate the midpoint of the thigh between the hip and knee. 

4. For gluteus medius, divide the buttock into quadrants, and inject in the upper outer quadrant to avoid hitting nerves or blood vessels. 

3. Preparing the Needle and Syringe: 

1. Draw the correct amount of medication into the syringe. 

2. Remove air bubbles by holding the syringe with the needle facing up and gently tapping it. 

4. Disinfecting the Site: 

1. Use an alcohol swab to clean the injection site in a circular motion from the center outward. 

2. Let it dry for a few seconds to avoid irritation. 

5. Administering the Injection: 

1. Hold the syringe like a dart, perpendicular to the skin. 

2. Insert the needle quickly and firmly into the muscle at a 90-degree angle. 

3. Aspirate (pull back on the plunger) to check for blood in the syringe. If blood enters the syringe, it means you’ve hit a blood vessel—remove the needle and choose a new site. 

4. Inject the medication slowly and steadily. 

5. Once the injection is complete, remove the needle quickly and apply gentle pressure to the site with a clean cotton ball or gauze. 

6. Post-Injection Care: 

1. Dispose of the needle and syringe in a proper sharps container. 

2. If necessary, apply a bandage to the site. 

3. Monitor the patient for any signs of allergic reactions or other adverse effects. 

Needle and Syringe Sizes for Intramuscular Injections 

• Needle Length: Typically, 1 to 1.5 inches for adults, and shorter needles (0.5 to 1 inch) for children. 

• Needle Gauge: The size depends on the medication, but a 22-25 gauge needle is common. 

• Syringe Size: The volume of medication determines the syringe size—usually between 1 to 5 mL. 

Complications and Considerations 

1. Pain at Injection Site: Pain, redness, and swelling can occur. Rotating sites of injection can help minimize discomfort. 

2. Nerve Damage: Incorrect needle placement can injure a nerve, particularly in the buttocks (e.g., sciatic nerve). 

3. Infection: Always use sterile needles, syringes, and equipment to prevent infection. 

4. Hematoma: This occurs when blood vessels are damaged, leading to a bruise. 

5. Fatigue and Weakness: If the needle is not inserted properly, it can cause significant discomfort.