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U N I T 2
Integrative Body Functions
capillary permeability are burn injury, inflammation,
and immune responses.
Obstruction of Lymphatic Flow.
Osmotically active
plasma proteins and other large particles that cannot be
reabsorbed through the pores in the capillary membrane
rely on the lymphatic system for movement back into
the circulatory system. Edema due to impaired lymph
flow is commonly referred to as
lymphedema
. Malignant
involvement of lymph structures and removal of lymph
nodes during cancer surgery are common causes of
lymphedema. Another cause of lymphedema is infection
and trauma involving the lymphatic channels and lymph
nodes.
Manifestations.
The effects of edema are determined
largely by its location. Edema of the brain, larynx, and
lungs are acute, life-threatening conditions. Non–life-
threatening edema may interfere with movement, limit-
ing joint motion. Swelling of the ankles and feet often
is insidious in onset and may or may not be associated
with disease. At the tissue level, edema increases the
distance for diffusion of oxygen, nutrients, and wastes.
Thus, edematous tissues usually are more susceptible
to injury and development of ischemic tissue damage,
including pressure ulcers. Edema can also compress
blood vessels. For example, the skin of a severely swol-
len finger can act as a tourniquet, shutting off the blood
flow. Edema can also be disfiguring, causing psycho-
logical effects and disturbances in self-concept, as well
as making it difficult to obtain proper-fitting clothing
and shoes.
Pitting edema
occurs when the accumulation of inter-
stitial fluid exceeds the absorptive capacity of the tis-
sue gel. In this form of edema, the tissue water becomes
mobile and can be translocated with pressure exerted
by a finger.
Nonpitting edema
in which the swollen area
becomes firm and discolored, occurs when plasma pro-
teins have accumulated in the tissue spaces and coag-
ulated. It is most commonly seen in areas of localized
infection or trauma.
Assessment and Treatment.
Methods for assessing
edema include daily weight (1 L of water weighs 2.2
pounds), visual assessment, measurement of the affected
part, and application of finger pressure to assess for pit-
ting edema. Daily weight measurements taken at the
same time each day with the same amount of cloth-
ing provide a useful index of water gain due to edema.
Visual inspection and measurement of the circumference
of an extremity can also be used to assess the degree
of swelling. This is particularly useful when swelling is
due to thrombophlebitis. Finger pressure can be used
to assess the degree of pitting edema. If an indentation
remains after the finger has been removed, pitting edema
is identified. It is evaluated on a scale of +1 (minimal) to
+4 (severe) (Fig. 8-5).
Distinguishing lymphedema from other forms of
edema can be challenging, especially early in its course.
Papillomatosis,
a characteristic honeycomb appearance
of the skin due to dilated lymph vessels that are envel-
oped in fibrotic tissue, distinguishes lymphedema from
other forms of edema. Computed tomography (CT) or
magnetic resonance imaging (MRI) may be used to con-
firm the diagnosis.
6
Treatment of edema usually is directed toward main-
taining life when the swelling involves vital structures,
correcting or controlling the cause, and preventing tissue
injury. Edema of the lower extremities may respond to
simple measures such as elevating the feet. Diuretic ther-
apy commonly is used to treat edema associated with an
increase in ECF volume. Serum albumin levels can be
measured, and albumin administered intravenously to
raise the plasma colloidal osmotic pressure when edema
is caused by hypoalbuminemia.
Elastic support stockings and sleeves increase intersti-
tial fluid pressure and resistance to outward movement
of fluid from the capillary into the tissue spaces. These
support devices typically are prescribed for patients
with conditions such as venous or lymphatic obstruc-
tion and are most efficient if applied before the tissue
spaces have filled with fluid—for example, in the morn-
ing before the effects of gravity have caused fluid to
move into the ankles. Moderate to severe lymphedema
is usually treated with light-pressure massage designed
to increase lymph flow by encouraging opening and
closing of lymph vessel valves; compression garments or
pneumatic compression pumps; range-of-motion exer-
cises; and scrupulous skin care to prevent infection.
6
Third-Space Accumulation
Third spacing represents the loss or movement and trap-
ping of ECF in a transcompartmental space. The serous
cavities are part of the transcompartmental compart-
ment (i.e., third space) located in strategic body areas
where there is continual movement of body structures—
the pericardial sac, the peritoneal cavity, and the pleural
cavity. The serous cavities, which are closely linked with
FIGURE 8-5.
3+ pitting edema of the left foot. (Used with
permission from Bates B. Bates’ Guide to Physical Examination
and HistoryTaking. 6th ed. Philadelphia, PA: J.B. Lippincott;
1995:438.)
