18
WOUND CARE TODAY
2015,Vol 2, No 1
FOCUS ON OEDEMA
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between the tissues, the blood and
the lymphatic system is balanced
so that the tissues retain their usual
appearance and function.
The venous and lymph systems
play an essential role in maintaining
fluid balance. The former carries
deoxygenated blood and by-products
of cellular activity back to the heart
via the liver and kidneys; whereas
the lymph system carries fluids,
fats and proteins back into general
circulation from the tissues so that
they do not accumulate in the
interstitial spaces (Green, 2007). Any
increase of fluid into the interstitial
spaces will also result in excess fluid
accumulation if not reabsorbed.
Certain diseases and/or
conditions affect the body’s ability to
balance fluid and waste production
with reabsorption. Oedema may
also occur due to a number of
more ‘systemic’ problems such
as heart failure, hepatic cirrhosis
and hypothyroidism. It may also
be caused by drugs such as the
calcium-channel blocker amlodipine,
non-steroidal anti inflammatory
medicines, and steroids (Keeley,
2008). The delicate balance of
filtration and reabsorbtion is key
to the maintenance of healthy skin
(Williams, 2003).
VENOUS SYSTEM
Return of deoxygenated blood from
the legs to the heart when the body
is in an upright position takes place
against the force of gravity. The
movement of the ankle and knee
activate the calf muscle pump, which
propels the blood in the deep veins
up towards the heart (see box left).
LYMPHATIC SYSTEM
The lymphatic system comprises
lymph capillaries, lymph vessels and
ducts, as well as other structures such
as ducts and nodes, which house vast
numbers of immune cells to fight
infection. Lymph fluid circulates in
the lymphatic system and it has an
important immunological function,
carrying foreign particles and cellular
debris to the lymph nodes (Green,
2007). Lymph capillaries are present
in the tissues of all organs.
The initial lymphatics are blind-
ended, with a single cell wall,
and flaps supported by anchoring
filaments open and shut in response
to changes in tissue pressures,
permitting extracellular fluid to pass
through (Starr et al, 2008).
Like veins, the larger lymph
vessels also have smooth muscle in
their walls and another similarity,
although more relevant to the
lymphatics, is that breathing and
muscle movement help to propel
lymph through the lymph vessels.
Lymph nodes are located at intervals
along the lymph vessels and white
blood cells (macrophages) within
the nodes help to clear the lymph of
bacteria, debris and other substances.
The lymph vessels eventually
converge at collecting ducts where
lymph fluid drains into the veins
in the lower neck. In this way, the
cleansed lymph fluid is returned to
the circulation (Starr et al, 2008).
PATIENT ASSESSMENT
It is essential that all patients who
Top tip:
Once oedema has been reduced,
a follow-up programme must
be initiated to monitor any
recurrence, control disease
progression and prevent the
complications of ulceration,
exudate and lymphorrhea
.
Table 1:
Scale for the assessment and categorisation of lymphoedema
Stage
Description
Stage I
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This represents early onset of the condition where there is accumulation
of tissue fluid that subsides with limb elevation. The oedema may be
pitting at this stage
Stage II
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Limb elevation alone rarely reduces swelling and pitting is manifest at
late stage II
Stage II late
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There may or may not be pitting as tissue fibrosis is more evident
Stage III
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The tissue is hard (fibrotic) and pitting is absent. Skin changes such as
thickening, hyperpigmentation, increased skin folds, fat deposits and
warty overgrowths develop
THE SCIENCE —
THE VENOUS SYSTEM
The venous valves open up as soon as blood is
pushed upwards and close when the muscles
relax (Partsch et al, 2006). Chronic venous
insufficiency occurs when these valves become
damaged, allowing the blood to flow backwards.
Valve damage may occur as the result of aging,
reduced mobility, extended periods of sitting or
standing, or a combination of these. The most
common cause is damage following deep venous
thrombosis (DVT) (post-thrombotic syndrome). The backflow of blood
increases venous pressure, resulting in venous hypertension. Exposing
the connecting and superficial veins to this constant high pressure also
increases the filtration rate into the interstitial spaces and leads to an
increased amount of interstitial fluid which may overload the lymphatic
system. As lymphatic drainage becomes further compromised, tissue
fibrosis can develop as a result of the inflammatory processes seen in
chronic oedema (Green and Mason, 2006).
