Healthcare and Medicine Reference
Access: Intravenous Cannulation
Anna Fergusson 1 and Oliver Masters 2
1 Russells Hall Hospital, Dudley, UK
2 Queen Elizabeth Hospital, Birmingham, UK
Infl ammation or infection of overlying skin at proposed
By the end of this chapter you should be able to:
discuss the indications and contraindications for peripheral
Arteriovenous (AV) fi stula in arm of proposed cannula site.
understand the anatomy of potential cannulation sites
Previous mastectomy with axillary node surgery or lymphoe-
identify the correct site and size for a cannula
dema on side of proposed upper limb cannulation.
understand the potential complications of peripheral cannulation
describe the technique for insertion of a cannula.
Veins of the forearm (elbow to wrist) in those with renal failure
who may require AV fi stula formation in the future.
Anatomy of veins
Veins consist of three layers: the tunica adventiticia, tunica media,
and tunica intima. Veins contain valves, folds of endothelium,
which assist with fl ow of blood back to the heart. Valves can
sometimes be identifi ed by palpation of small bulges in the vein.
Figure 10.1 shows the anatomy of the veins of the hand.
Peripheral venous cannulation is one of the most common
invasive procedures carried out in hospital. Thousands of cannu-
lae are inserted every day in the UK, mostly by junior doctors or
nurses. Peripheral venous cannulation is associated with signifi cant
morbidity and mortality - mainly secondary to infection. It has
been estimated that an epsiode of bacteraemia occurs for 1 in every
100 peripheral cannulae sited. It is therefore essential not only to be
capable of competently putting in a cannula correctly, but also to
do this in a safe manner.
Before inserting a cannula it is essential to determine whether
or not there is a clinical indication. Studies show that up to one
third of cannulae in hospitalised patients are not required or are
not being used. Alternatives to cannulation should be considered
where possible; for example oral antibiotics instead of intravenous
antibiotics, or encouragement of oral fl uid intake instead of intra-
venous fl uids.
A cannula is composed of several parts: the needle, catheter, wings,
valve, injection port and Luer-Lok™ cap. Most cannulae also
contain a 'fl ashback chamber' giving the practitioner visual confi r-
mation that the cannula has entered the vein. Figure 10.2 shows a
labelled diagram of a cannula.
Modern peripheral cannulae are made from polyurethane. This
is preferable to older materials such as PVC and Tefl on® as the can-
nulae are more fl exible, softer and cause less intimal damage. They
are also latex free.
Table 10.1 shows sizes of cannulae, colour, fl ow rates and
uses. Remember that the maximum fl ow rate is printed on the
packaging of most cannulae - important if you are fl uid
Intravenous fl uids.
Intravenous drugs - continuous or intermittent.
Blood or blood products.
Intravenous radio-opaque contrast or sedation.
Prophylactic use in unstable patients or those undergoing
Choosing the appropriate cannula
Deciding on the appropriate-sized cannula and the appropriate
vein will depend on a number of factors. In a resuscitation situ-
ation, or if the patient is unstable, the biggest cannula that the