The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [557]
Box 13.11 Types of injections and infusions
Intradermal injection.
Subcutaneous injection and infusion.
Intramuscular injection.
Intra-arterial injection.
Intraosseous injection.
Intra-articular injection.
Intrathecal injection and infusion.
Intravenous:
– Bolus injection
– Intermittent and continuous infusion.
Injections can be described as the act of giving medication by use of a syringe and needle. An infusion is defined as an amount of fluid in excess of 100 mL designated for parenteral infusion because the volume must be administered over a long period of time. However, medications may be given in small volumes (50–100 mL) or over a shorter period (30–60 minutes) (Weinstein and Plumer 2007).
Anatomy and physiology
The skin is made up of two layers: the dermis and epidermis. Within the dermis there is the papillary layer (upper dermal region) which contains capillaries, pain and touch receptors. The reticular layer contains blood vessels, sweat and oil glands. Both collagen and elastic fibres are found throughout the dermis. Collagen fibres are responsible for the toughness of the dermis. The skin also has a rich nerve supply (Marieb and Hoehn 2007). There are three types of muscles – skeletal, cardiac and smooth. Skeletal muscles are attached to the body’s skeleton and are also known as striated muscle because the fibres appear to be striped (Marieb and Hoehn 2007). For specific muscles used for injections, see intramuscular injection sites.
Evidence-based approaches
Medicines should only be administered by injection when no other route is suitable or available. As injections avoid the GI tract, this is described as parenteral administration. Injections would be administered when the medications might be destroyed by the stomach; rapid first-pass metabolism may be extensive; the drug is not absorbed when given orally; precise control over dosage is required; unable to be given by mouth; achieve high drug plasma levels (Downie et al. 2003, Perry 2007). There are disadvantages as injections are invasive, cause pain and discomfort, and can put the patient at risk of infection and, in the case of intravenous injections, infiltration and extravasation.
Methods for injection or infusion
There are a number of routes for injection or infusion. See Box 13.11. The selection may be predetermined, for example intra-arterial, intracardiac injections. The choice of other routes will normally depend on the desired therapeutic effect and the patient’s safety and comfort.
Intra-arterial
This special technique allows the delivery of a high concentration of drug to the tissues or organ supplied by a particular artery if the medications are rapidly metabolized or systematically toxic (Downie et al. 2003). This route can be used for the administration of chemotherapy and vasodilators and for diagnostic purposes. Injection of drugs into an artery is a rare and hazardous procedure. The introduction of the cannula or catheter must be performed with care as the vessel may go into spasm, causing pain and occlusion. This could result in necrosis of an organ or part of a limb. Injection of irritant chemicals increases the risk of spasm and its sequelae; however, arterial catheterization is occasionally performed when it is desirable to deliver a high concentration of a drug to a tumour mass. The most common procedures are catheterization of the hepatic artery and isolated limb perfusion.
Intra-articular
In inflammatory conditions of the joints, corticosteroids are given by intra-articular injection to relieve inflammation and increase joint mobility (Downie et al. 2003).
Intraosseous
This route is used for emergency or short-term treatment when access by the vascular route is difficult or cannot be achieved and the patient’s condition is considered life threatening (RCN 2010). The preferred sites are the iliac crest or sternum (RCN 2010). Any drug administered intravenously