Intramuscular injections

To avoid confusion: You must follow local policies and procedures regarding technique, equipment used and documentation.

Definition

An intramuscular injection deposits medication into deep muscle tissue under the subcutaneous tissue. The vascularity of muscle aids the rapid absorption of medication (Royal Marsden 2015). Intramuscular (IM) refers to injection of a drug directly into the muscle. The effect of medicines given IM will be faster than those given by subcutaneous (SC) injection but slower than drugs given intravenously (IV).

Intramuscular injection sites

IM injections are typically administered into the deltoid, the gluteal or the quadricep muscle beds. There are five recommended injection sites located within these muscle groups: the deltoid, vastus lateralis, rectus femoris, dorsogluteal and ventrogluteal sites.

The dorsogluteal (gluteus maximus) site is potentially associated with more risks due to the presence of major blood vessels and nerves. Also, the drug absorption rate is much lower in gluteal muscles. If the patient is obese (i.e. has large amounts of adipose tissue), it is harder to be confident that the injection will reach the gluteus maximus so the vastus lateralis may be a better site. Smaller IM injections, such as vaccinations, are usually given into the deltoid area (Figure 2). Do not use sites where the skin is broken, oedematous, or there is scarring.

• Selecting the site requires correct identification of the muscle groups by using landmarks to identify the relevant anatomical features.

• Choice will be influenced by the patient's physical condition and age.

• Intramuscular injections should be given into the densest part of the muscle.

• Active patients will probably have greater muscle mass than older or emaciated patients

• The choice of muscle bed depends on the volume of medication to be injected; however, it appears that it is the medicine rather than just the volume that affects how a patient tolerates an injection.

(Royal Marsden 2005)

Vastus Lateralis Intramuscular injection

This short animation clearly shows the underlying muscle, nerve and bone structures that you should consider when administering an intramuscular injection

Dorso-gluteal:Intramuscular injection site

This short animation clearly shows the underlying muscle, nerve and bone structures that you should consider when administering an intramuscular injection

Deltoid: intramuscular injections site

This short animation clearly shows the underlying muscle, nerve and bone structures that you should consider when administering an intramuscular injection

The IM route is only suitable for small volumes of drugs, up to 5 mL in large muscle (vastus lateralis and ventrogluteal) and 2 mL in small muscle (e.g. deltoid); however, most IM injections will be no more than 2 mL as large volumes can be very painful. Examples of medicines given intramuscularly are analgesics, anti-emetics, and immunisations.

Drawing up liquid for injections

Drawing up a liquid medicine for injection is required for intramuscular (IM) and intravenous (IV) injections. Some subcutaneous (SC) and most intradermal injections come in prefilled syringes and so no drawing up is required.

The following will focus on the technique for drawing up the liquid into a syringe for injection.

When drawing up a liquid it is vital to use an aseptic non-touch technique (ANTT) to maintain sterility and a good technique to prevent needlestick injuries. Used needles must never be re-sheathed but the blunt needle used to draw up the liquid may be re-sheathed using a non-touch technique.

A safety-engineered syringe/needle should be used to protect professional healthcare workers from needlestick injuries, the transmission of bloodborne pathogens and exposure to hazardous medicines. These mechanisms are either built into the syringe or single-use needles. All needles and syringes must be discarded immediately after use so you must take a sharps container with you to the patient.

A video is below to help you understand how to draw up medication to be given to a patient intramuscularly

Rate of administration

It is recommended that the plunger is depressed at a rate of 10 seconds per millilitre (Royal Marsden 2005)

Pre-procedural considerations

Equipment

The most common size of needle is 21 G (23 G may also be used in a thin patient) but it does depend on the viscosity of the medication. The important aspect of the needle is the length. The correct use of needle length will result in fewer adverse events and reduce complications of absecess, pain and bruising (Malkin 2008). Needles should be long enough to penetrate the muscle and still allow a quarter of the needle to remain external to the skin (Workman 1999). Lenz (1983) states that when choosing the correct needle length for intramuscular injections, it is important to assess the muscle mass of the injection site, the amount of subcutaneous fat and the weight of the patient. It may be necessary to calibrate the BMI to calculate body fat (Public Health England 2006). Without such an assessment, most injections intended for gluteal muscle are deposited in the gluteal fat. The following are suggested as ways of determining the most suitable size of needle to use.

Deltoid and vastus lateralis muscles

The muscle to be used should be grasped between the thumb and forefinger to determine the depth of the muscle mass or the amount of subcutaneous fat at the injection site.

Gluteal muscles

The layer of fat and skin above the muscle should be gently lifted with the thumb and forefinger for the same reasons as before.

The patient’s weight indicates the length of needle to use.

Remember women have more subcutaneous tissue than men so a longer needle will be needed (Pope 2002).

Specific patient preparation

Skin preparation

There are differences in opinion regarding skin cleaning prior to subcutaneous or intramuscular injections. Previous studies have suggested that cleaning with an alcohol swab is not always necessary, as not cleaning the site does not result in infections and may predispose the skin to hardening (Dann 1969, Koivistov and Felig 1978, Workman 1999).

Dann (1969), in a study over a period of 6 years involving more than 5000 injections, found no single case of local and/or systemic infection. Koivistov and Felig (1978) concluded that whilst skin preparations did reduce skin bacterial count, they are not necessary to prevent infections at the injection site. Some hospitals accept that if the patient is physically clean and the nurse maintains a high standard of hand hygiene and asepsis during the procedure, skin disinfection is not necessary (Workman 1999).

In the immunosuppressed patient, the skin should be cleaned as such patients may become infected by inoculation of a relatively small number of pathogens (Downie et al. 2003). The practice at the Royal Marsden Hospital is to clean the skin prior to injection in order to reduce the risk of contamination from the patient’s skin flora. The skin is cleaned using an ‘alcohol swab’ (containing 70% isopropyl alcohol) for 30 seconds and then allowed to dry. If the skin is not dry before proceeding, skin cleaning is ineffective and the antiseptic may cause irritation by being injected into the tissues (Downie et al. 2003).

"After the injection

• After the IM injection has been administered, the nurse should assist the individual to get dressed, if required, and thank them for consenting to the procedure.

• The nurse also needs to ensure that they have safely disposed of all sharps, clean the clinical area and wash their hands.

• It is important for the nurse to check that the patient is comfortable, and to offer emotional support and reassurance if necessary.

• The nurse should check the injection site for any changes in presentation against the baseline assessment and observe the patient for any side effects or allergic reactions.

• The nurse also needs to remind the patient to inform a health care worker if in-patient in hospital, or contact a health care worker (key worker) or their GP for medical advice if they feel unwell or experience any soreness, pain or unusual discomfort at the injection site.

Documentation

• Documentation is a fundamental professional requirement in nursing, and it needs to be completed accurately and in a timely manner (NMC 2018).

The following nursing documentation is required for IM injections:

» The patient’s full name and date of birth.

» The rationale for the medicine prescribed and the use of the IM route.

» That the patient’s gave consent for the procedure.

» The patient’s preferred site for receiving IM injections and the site that was used to administer the medicine.

» The condition of the individual’s skin around the injection site before and after the medicine was administered.

» The patient’s preferred position when receiving an IM injection, for example standing, sitting or lying down.

» The patient’s response to the IM injection, including any side effects, pain or distress and adverse reactions."

(McAleer and Marsh 2021)

"Associated Risks and Complications

The administration of IM injections can lead to various complications, such as cellulitis, haematoma and sciatic nerve damage, leading to profuse bleeding, loss of function and tissue fibrosis that limits muscle flexibility (Gülnar and Özveren 2016). However, the risk of these complications can be reduced by alternating the injection site used (Lister et al 2020). Profuse bleeding and loss of function have also been linked to IM injections administered at the dorsogluteal site, which contains more major nerve and vascular structures than other sites. Therefore, aspirating the needle is recommended to ensure it has entered the muscle rather than these structures (Sisson 2015).

Increased risk of injury to the patient is associated with unsafe injection technique (Brown et al 2015). Abscess formation and tissue necrosis can occur when injections are delivered into the subcutaneous or adipose tissue layers rather than the muscle (Ogston-Tuck 2014). Delivering the medicine into the subcutaneous tissue results in slower absorption and reduced bioavailability. Inappropriate delivery into the subcutaneous layer may also contravene the medicine’s licence and result in legal ramifications (White et al 2018). The risk of inappropriate delivery into the subcutaneous or adipose layer can be reduced by selecting the appropriate needle size for the intended site, based on the patient’s body mass index (White et al 2018)."

(McAleer and Marsh 2021)

The following paper by Eileen Shepherd who explains how to give intramuscular injections will consolidate knowledge