510
U N I T 5
Circulatory Function
respiratory distress syndrome (ALI/ARDS) is
characterized by changes in the permeability of the
alveolar–capillary membrane with development
of interstitial edema and severe hypoxemia that
is refractory to oxygen therapy.The renal tubules
are particularly vulnerable to ischemia, and acute
kidney injury is an important complication of
shock. Gastrointestinal ischemia may lead to
gastrointestinal bleeding and increased vascular
permeability to intestinal bacteria, which can
cause further sepsis and shock. Disseminated
intravascular coagulation (DIC) is characterized by
formation of small clots in the circulation. Multiple
organ dysfunction syndrome (MODS), perhaps
the most ominous complication of shock, rapidly
depletes the body’s ability to compensate and
ultimately recover from the shock state.
SUMMARY CONCEPTS
(continued)
R E V I EW E X E R C I S E S
1.
A 75-year-old woman with long-standing
hypertension and angina due to coronary heart
disease presents with ankle edema, nocturia,
increased shortness of breath with activity, and
a chronic nonproductive cough. Her blood
pressure is 170/80 and her heart rate 92.
Electrocardiography and chest radiography indicate
the presence of left ventricular hypertrophy.
A.
Relate the presence of uncontrolled
hypertension and coronary artery disease to the
development of heart failure in this woman.
B.
Explain the significance of left ventricular
hypertrophy in terms of both a compensatory
mechanism and a pathologic mechanism in the
progression of heart failure.
C.
Use Figure 20-2 to explain this woman’s
symptoms, including shortness of breath and
nonproductive cough.
2.
A 26-year-old man is admitted to the emergency
department after an automobile injury with
excessive blood loss. He is alert and anxious,
his skin is cool and moist, his heart rate is 135,
and his blood pressure is 100/85. He is receiving
intravenous fluids, which were started at the scene
of the accident by an emergency medical technician.
He has been typed and cross-matched for blood
transfusions and a urinary catheter has been inserted
to monitor his urinary output. His urinary output
has been less than 10 mL since admission and his
blood pressure has dropped to 85/70. Efforts to
control his bleeding have been unsuccessful and he
is being prepared for emergency surgery.
A.
Use information regarding the compensatory
mechanisms in circulatory shock to explain this
man’s presenting symptoms, including urinary
output.
B.
Use Figure 20-8 to hypothesize about this man’s
blood loss and maintenance of blood pressure.
C.
The treatment of hypovolemic shock is
usually directed at maintaining the circulatory
volume through fluid resuscitation rather than
maintaining the blood pressure through the use
of vasoactive medications. Explain.
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