440
U N I T 5
Circulatory Function
malaise, and an elevated white blood cell count and
erythrocyte sedimentation rate are accompanying indi-
cations of inflammation. There may be tenderness and
pain along the vein. Swelling may vary from minimal
to maximal. As many as 50% of persons with DVT are
asymptomatic.
The site of thrombus formation determines the loca-
tion of the physical findings. The most common site is
in the venous sinuses in the soleus muscle and poste-
rior tibial and peroneal veins. Swelling in these cases
involves the foot and ankle, although it may be slight or
absent. Calf pain and tenderness are common. Femoral
vein thrombosis produces pain and tenderness in the
distal thigh and popliteal area. Thrombi in ileofemoral
veins produce the most profound manifestations, with
swelling, pain, and tenderness of the entire extremity.
With DVT in the calf veins, active dorsiflexion produces
calf pain (i.e., Homans’ sign).
Diagnosis andTreatment
The risk of pulmonary embolism emphasizes the need
for early detection and treatment of DVT.
81
Several
tests are useful for this purpose: ascending venography,
ultrasonography (e.g., real time, B mode, duplex), and
plasma
d
-dimer (a degradation product of fibrin) assess-
ment
84
(see Chapter 23).
Whenever possible, venous thrombosis should be
prevented in preference to being treated. Early ambu-
lation after childbirth and surgery is one measure that
decreases the risk of thrombus formation. Exercising
the legs and wearing support stockings improve venous
flow. A further precautionary measure is to avoid
assuming body positions that favor venous pooling.
Antiembolism stockings of the proper fit and length
should be used routinely in persons at risk for DVT.
Another strategy used for immobile persons at risk for
development of DVT is a sequential pneumatic com-
pression device. This consists of a plastic sleeve that
encircles the legs and provides alternating periods of
compression on the lower extremity. When properly
used, these devices enhance venous emptying to aug-
ment flow and reduce stasis.
The objectives of treatment of venous thrombosis are
to prevent the formation of additional thrombi, prevent
extension and embolization of existing thrombi, and
minimize venous valve damage.
83,84
Anticoagulation
therapy (i.e., warfarin and low–molecular-weight war-
farin) is used to treat and prevent venous thrombosis
(see Chapter 12). A 15- to 20-degree elevation of the
legs prevents stasis. It is important that the entire lower
extremity or extremities be carefully extended to avoid
acute flexion of the knee or hip. Heat often is applied
to the leg to relieve venospasm and to aid in the reso-
lution of the inflammatory process. Bed rest usually is
maintained until local tenderness and swelling have sub-
sided. Gradual ambulation with elastic support is then
permitted. Standing and sitting increase venous pressure
and are to be avoided. Elastic support is needed for 3 to
6 months to permit recanalization and collateralization
and to prevent venous insufficiency.
R E V I EW E X E R C I S E S
1.
The Third Report of the NCEP Expert Panel on
Detection, Evaluation, and Treatment of High
Blood Cholesterol in Adults recommends that a
person’s high density lipoprotein (HDL) should be
above 40 mg/dL.
A.
Explain the role of HDL in prevention of
atherosclerosis.
2.
A 55-year-old man presents at the emergency
department of his local hospital with complaints of
excruciating, “ripping” pain in his upper back. He
has a history of poorly controlled hypertension. His
radial pulse and blood pressure, which on admission
were 92 and 140/80 mm Hg, respectively, become
unobtainable in both arms. A transesophageal
echocardiogram reveals a dissection of the
descending aorta. Aggressive blood pressure control
is initiated with the goal of reducing the systolic
pressure and pulsatile blood flow (pulse pressure).
SUMMARY CONCEPTS
■■
Veins are thin-walled, distensible vessels that
collect blood from the tissues and return it to the
heart.The venous system is a low-pressure system
that relies on the pumping action of the skeletal
muscles to move blood forward and the presence
of venous valves to prevent retrograde flow.
■■
The storage function of the venous system
renders it susceptible to venous insufficiency,
stasis, and thrombus formation. Disorders of
the venous system produce congestion of the
affected tissues and predispose to clot formation
because of stagnation of flow and activation of
the clotting system.
■■
Varicose veins are dilated and tortuous veins
that result from a sustained increase in pressure
that causes the venous valves to become
incompetent, allowing for reflux of blood and
vein engorgement.
■■
Venous insufficiency, which is associated with
stasis dermatitis and venous ulcers, reflects
chronic venous stasis resulting from valvular
incompetence.
■■
Thrombophlebitis refers to thrombus formation
in a vein and the accompanying inflammatory
response in the vessel wall as a result of
conditions that obstruct or slow blood flow,
increase the activity of the coagulation system, or
cause vessel injury. Deep vein thrombosis may be
a precursor to pulmonary embolism.
