Healthcare and Medicine Reference
In-Depth Information
and pressure applied to the area for at least 3 minutes to reduce
Occasionally it is possible to 'hit a valve'. This may manifest in
diffi culty threading the cannula up the vein. Careful palpation of
the vein to locate the valves may help avoid this problem; valves can
be felt as small bulges. It may also be possible to advance the can-
nula while fl ushing it with normal saline. This may cause the valve
to open to allow the cannula through.
Rarely, an artery can be cannulated accidentally. This may have
catastrophic consequences if unrecognised and the cannula is used
to administer drugs. It is more likely to occur when cannulating
veins in the antecubital fossa or the cephalic vein. At these sites
either the brachial artery or an anatomical variant of the radial
artery may be cannulated. Arterial cannulation is more likely in
overweight patients, where the veins are very deep and diffi cult to
palpate, or in very thin patients. It is usually obvious as the blood
is redder than expected and pulsatile. If there is any doubt the
cannula should be removed immediately and pressure applied for
at least 5 minutes.
Needlestick injuries can occur when cannulating. Self-blunting
or retractable cannula are available, minimising the risk of needle-
stick injuries, and should be used where possible. For further
information on needlestick injuries refer to Chapter 3.
pulmonary circulation. There is also a small risk of air embolism,
especially if care is not taken to prime all administration equipment
Extravasation, or 'tissueing', is a common problem, occurring
in up to a quarter of those receiving intravenous infusions. This
occurs when infusion fl uid or drug leaks into the subcutaneous tis-
sues surrounding the vein, normally when the cannula is dislodged
from the vein or the tip is sitting in the vessel wall. Extravasation
presents with localised pain and swelling. Careful monitoring of
the cannula site is needed, especially in those who cannot commu-
nicate effi ciently, such as children, the elderly or those with reduced
Care of cannula site
Once inserted, the cannula should be secured appropriately, using
a purpose-made adhesive dressing. This should be transparent
around the cannula site to allow direct inspection when looking for
any signs of phlebitis. It may be necessary to apply a loose-fi tting
bandage over the cannula to increase its security, especially in a
confused or agitated patient. In this case it is vital that the bandage
is regularly removed to actively look for any evidence of phlebitis.
The cannula site should be inspected every 8 hours as a mini-
mum, and a phlebitis scale used, such as the Visual Infusion
Phlebitis score (VIP score - see Table 10.2). If phlebitis is noted, this
Late complications
Phlebitis is infl ammation of the vein and can be due to chemical or
mechanical irritation, or infection. Thrombophlebitis occurs when
phlebitis is associated with formation of a thrombus within the
vessel. Phlebitis and thrombophlebitis are extremely common,
occurring in up to 35% of cannulations. They present with ery-
thema, swelling, warmth, tenderness, and occasionally a palpable
venous cord. Risk factors include the length of time the cannula is
in situ, infusion of irritant drugs or fl uids, and which material the
cannula is manufactured from.
The vast majority of infective phlebitis is superfi cial and requires
no treatment other than removal of the cannula. Oral antibiotics
may be considered. Occasionally, systemic sepsis can occur, with
an incidence of 1 per 3000 peripheral cannulae in one large study.
Between 1997 and 2002, 6.2% of hospital-acquired bacteraemias
were caused by peripheral IV cannulae.
Contamination can occur when skin fl ora is introduced at
cannula insertion or by the introduction of other organisms via
the cannula hub or injection port. The commonest organisms
responsible for infective phlebitis are coagulase-negative staphylo-
coccus and Staphylococcus aureus (40-45% of which are methicillin-
resistant Staphylococcus aureus ).
The risk of cannula site infection can be minimised by using
an aseptic technique (particularly important in patients who are
immunosuppressed), regular inspection, and minimal time in situ
(no cannula should be left in situ for more than 72 hours). A high
index of suspicion is vital in any patient with a cannula in situ
who becomes septic with no obvious cause. Finally, it is important
to assess each patient's clinical indication and avoid cannulation
where possible.
Thromboembolism can occur, where blood clots on the cannula
or vein wall before breaking off and being carried into the heart and
Table 10.2 Visual Infusion Phlebitis (VIP) score. Developed by Andrew
Jackson, Consultant Nurse Intravenous Therapy and Care, Rotherham
General Hospitals NHS Trust.
IV site appears healthy
No signs of phlebitis
Observe cannula
One of the following is evident:
Slight pain near IV site
Possible signs of phlebitis
Observe cannula
Slight redness near IV site
Two of the following are evident:
Pain near IV site
Early stages of phlebitis
Resite cannula
All of the following are evident:
Pain along path of cannula
Medium stage of phlebitis
Resite cannula
Consider treatment
All of the following are evident
and extensive:
Pain along path of cannula
Advanced stages of phlebitis or
start of thrombophlebitis
Resite cannula
Consider treatment
Palpable venous cord
All of the following and evident
and extensive:
Pain along path of cannula
Advanced stage of
Initiate treatment
Resite cannula
Palpable venous cord
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