Chapter 17: Vascular access devices: insertion and management
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Anatomy and physiology
Choice of vein
The main factors to consider prior to inserting a peripheral cannula are the location for siting, the condition of the vein, the purpose of the infusion (i.e. the rate of flow required and the solution to be infused) and the duration of therapy (Dougherty [124], Phillips [371], RCN [381]).
A suitable vein should always be determined prior to selection of the device. The vein should feel bouncy, refill when depressed, and be straight and free of valves to ensure easy advancement of the cannula. Valves can be felt as small lumps in the vein; some may be visualized at bifurcations, whereas some may be visible to the naked eye in certain vessels. It is best to avoid siting a cannula over a joint as this increases the risk of mechanical phlebitis and an infusion that will infuse intermittently due to the patient's movement (Dougherty [124], Gorski et al. [181], RCN [381], Witt [475]). It can also be very awkward for the patient and may restrict their ability to carry out activities (Macklin and Chernecky [287], Marsigliese [297]).
The veins of choice are either the cephalic or the basilic veins, followed by the dorsal venous network (see Figure 17.1). The practitioner should choose distal veins and then cannulate at proximal points (Gorski et al. [181], Perucca [369]). The best vein should always be used (Weinstein and Hagle [465]).
The cephalic vein
The size and position of the cephalic vein make it an excellent vessel for administration of transfusions. It readily accommodates a large‐gauge cannula and, by virtue of its position on the forearm, provides a natural splint (Weinstein and Hagle [465]). However, its position at a joint may increase complications, such as mechanical phlebitis and even general discomfort. The tendons controlling the thumb obscure the vein during insertion (Hadaway [194]), and care must be taken not to touch the radial nerve (Dougherty [124]).
The basilic vein
The basilic vein is a large vessel that is often overlooked due to its inconspicuous position on the ulnar border of the hand and forearm. It is found on palpation when the patient's arm is placed across the chest, with the practitioner opposite the patient (Hadaway [194]). Cannulation can be awkward because of its position, mobility and tendency to have many valves (Dougherty [124], Hadaway [194]).
The dorsal venous network
Using the veins of the dorsal venous network of the hand allows for cannulation proximally along the veins when re‐siting a device (Weinstein and Hagle [465]). These veins can usually be visualized and palpated easily (Hadaway [194]):
- The digital veins are small and may be prominent enough to accommodate a small‐gauge needle as a last resort for fluid administration. With adequate taping, the fingers can be immobilized, making them more comfortable as well as preventing the cannula from piercing the posterior wall of the vein (leading to bruising or infiltration) (Springhouse [426]).
- The metacarpal veins are accessible, and easily visualized and palpated. They are well suited for cannulation as the cannula lies flat and the metacarpal veins provide a natural splint (Weinstein and Hagle [465]). The veins tend to be smaller than those in the forearm and therefore may prove difficult to access in infants because they have higher amounts of subcutaneous fat than older children and adults. The use of these veins is contraindicated in the elderly as there is diminished skin turgor and loss of subcutaneous tissue, making the veins difficult to stabilize. They are also more fragile and venous distension is slower (Fabian [141], Hadaway [194], Springhouse [426]). Metacarpal veins are a better option for short‐term or outpatient intravenous therapy.
