Intramuscular Injection – Types, Technique, Procedure - Health

Intramuscular Injection is the method of installing medications into the depth of the bulk of specifically selected muscles. The basis of this process is that the bulky muscles have good vascularity, and therefore the injected drug quickly reaches the systemic circulation and thereafter into the specific region of action, bypassing the first-pass metabolism.[rx] It is one of the most common medical procedures to be performed on an annual basis. However, there is still a lack of uniform guidelines and an algorithm in giving IM among health professionals across the world.[rx] [rx]

Intramuscular injection, often abbreviated IM, is the injection of a substance directly into the muscle. In medicine, it is one of several methods for parenteral administration of medications. Muscles have larger and more numerous blood vessels than subcutaneous tissue; intramuscular injections usually have faster rates of absorption than subcutaneous or intradermal injections.^[rx] The volume of injection is limited to 2-5 milliliters, depending on the injection site.

Anatomy and Physiology of Intramuscular Injection

Anatomical Landmarks

There are specific landmarks to be taken into consideration while giving IM injections so as to avoid any neurovascular complications. The specific landmarks for the most commonly used sites are discussed below

Dorsogluteal Region

5 to 7.5 cm below the iliac crest.
Upper outer quadrant of the upper outer quadrant within the buttocks[3]

Ventrogluteal Region

The heel of the opposing hand is placed in the greater trochanter, the index finger in the anterior superior iliac spine and the middle finger below the iliac crest. The drug is injected in the triangle formed by the index, middle finger, and the iliac crest[rx][rx]

Deltoid

2.5 to 5 cm below the acromion process

Vastus Lateralis

Possible sites for IM injection include – deltoid, dorsogluteal, rectus femoris, vastus lateralis and ventrogluteal muscles. Sites that are bruised, tender, red, swollen, inflamed or scarred are avoided.
The middle third of the line joining the greater trochanter of the femur and the lateral femoral condyle of the knee[rx]

Uses of Intramuscular Injection

Drugs may be given intramuscularly both for prophylactic as well as curative purposes, and the most common medications include[rx]:

Antibiotics- penicillin G benzathine penicillin, streptomycin
Biologicals- immunoglobins, vaccines, and toxoids
Hormonal agents- testosterone, medroxyprogesterone

Any drugs that are nonirritant and soluble may be given IM during an emergency scenario.

Examples of medications that are sometimes administered intramuscularly are:

Atropine
Haloperidol (Haldol)
Aripiprazole (Abilify)
Paliperidone (Invega)
Chlorpromazine (Thorazine)
Lorazepam (Ativan)
Fulvestrant (Faslodex)
Codeine
Morphine
Methotrexate
Metoclopramide
Magnesium sulfate
Olanzapine
Streptomycin
Diazepam
Prednisone
Penicillin
Interferon beta-1a
Sex hormones, such as testosterone, estradiol valerate, and medroxyprogesterone acetate (as Depo Provera)
Dimercaprol
Ketamine
Leuprorelin
Naloxone
Quinine, in its gluconate form
Vitamin B12, as cyanocobalamin, hydroxocobalamin or methylcobalamin
Risperidone

Vaccines are often administered as IM injections.

In addition, some vaccines are administered intramuscularly:

Gardasil
Hepatitis A vaccine
Rabies vaccine
Influenza vaccines based on inactivated viruses are commonly administered intramuscularly (although there is active research being conducted as to the best route of administration).
Platelet-rich plasma injections can be administered intramuscularly.
Certain substances (e.g. ketamine) are injected intramuscularly for recreational purposes.

Indications of Intramuscular Injection

IM is commonly indicated for patients who are

Noncompliant
Uncooperative
Reluctant
Unable to receive drugs through other commonly utilized routes[rx]

Contraindications of Intramuscular Injection

Active infection, cellulitis or dermatitis at the site of administration
Known allergy or hypersensitivity to the drug
Acute myocardial infarction- the release of muscle enzymes may provide a confounding bias in making the diagnosis
Thrombocytopenia
Coagulation defects
Hypovolemic shock- the absorption of the drug may be hampered owing to compromised vascularity to the muscle
Myopathies
Associated muscular atrophy- leads to delayed drug absorption as well as adds up the risk of neurovascular complications

Equipment

20-25 gauge syringe with a needle length of 16-38 mm
Filter needle
Alcohol-based antiseptic solution
The correct drug in an appropriate dose
Dry cotton swab
Self-adhesive bandage
Needle disposal unit
A trained nurse or a paramedics
The treating physician

Preparation

Prerequisite-

Ensure the 5 ‘Rs’

Right patient
Right drug
Right dose
Right site
Right timing

Ask for any adverse reactions in previous such procedures.

Counseling regarding the procedure and preparing the patient– to calm them down and also to minimize the pain associated with the procedure

Site selection

Infants- vastus lateralis
Children- vastus lateralis and deltoid
Adults- ventrolateral and deltoid[rx]

Drug volume

2 ml or less- deltoid injection
2 to 5 ml – Ventrogluteal injection[rx]

Needle length

Vastus lateralis -16 to 25 mm
Deltoid-16 to 32 mm (children), 25 to 38 mm(adults)
Ventrogluteal-38 mm[rx]

Technique of Intramuscular Injection

The sequential method of IM injection can be summarised as follows[rx][rx][rx]

Thorough cleaning of the hands
Application of sterile gloves
Thorough cleansing surrounding the site of injection with an alcohol-based antiseptic solution
Perpendicular insertion of a needle of appropriate sized length[rx]
Prepare the drug and then aspirate it from the filter needle
Insure intramuscular positioning of the needle via confirming restricted side to side movement of the needle as opposed to when the needle is in the subcutaneous plane
Aspirate to rule out any egress of blood especially in cases of dorsogluteal injection due to inadvertent vascular puncturing of the gluteal artery during the procedure[rx][rx]
Slow injection of the drug at 10 sec/ml
Slow withdrawal the needle and then apply gentle pressure over the injected site with a dry cotton swab
Proper disposal of all the equipment used during the procedure[rx]
Assessment of the injected region for probable early and late complications

Complications

Common complications associated with the intramuscular injection can be summarized as [rx]:

Muscle fibrosis and contracture
Abscess at the injection site
Gangrene
Nerve injury -the sciatic nerve in gluteal injection, the femoral nerve in vastus lateralis injection
Vascular injury- the superior gluteal nerve in dorsogluteal injection, the femoral nerve in vastus lateralis injection, radial nerve in deltoid injection
Skin slough
Periostitis
Transmission of HIV, hepatitis virus
Persistent pain at the site of injection

Clinical Significance

Advantages

Rapid and uniform absorption of the drug especially those of the aqueous solutions
Rapid onset of the action compared to that of the oral and the subcutaneous routes
IM injection bypasses the first-pass metabolism
It also avoids the gastric factors governing the drug absorption
Has efficacy and potency comparable to that of the intravenous drug delivery system.
Highly efficacious in emergency scenarios such as acute psychosis and status epilepticus
Depot injections allow slow, sustained and prolonged action
A large volume of the drug can be administered compared to that of the subcutaneous route

Disadvantages

Expert and a trained person is required for administrating the drug by IM route
The absorption of the drug is determined by the bulk of the muscle and its vascularity
The onset and duration of the action of the drug is not adjustable
In case of inadvertent scenarios such as anaphylaxis or neurovascular injuries, intravenous (IV) assess needs to be secured
IM injection at the appropriate landmarks may be difficult in a child as well as in patients requiring physical restrain
Inadvertent injection in the subcutaneous plane of the fascia can lead to delayed action of the drug
Painful procedure
Suspensions, as well as oily drugs, cannot be administered
Can lead to anxiety to the patient especially in children
Self-administration of the drug can be difficult
The precipitation of the drug following faster absorption of the solvent may lead to delayed and prolonged action of the drug
Unintended prolonged sequelae following delayed drug release from the muscular compartment
Need for temporary restraint of the patients especially in cases with children

References

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Intramuscular Injection – Types, Technique, Procedure