Page 102 - Concise Pathology for Exam Preparation ( PDFDrive )

4 Haemodynamic Disorders, Thrombosis and Shock 87

Adult respiratory distress syndrome (ARDS)
(c)
of
(d)
Ischaemic cell death brain, heart and kidney
Causes of Irreversibility

• �Widespread vasoconstriction starts compensatory mechanism but its persistence

a

as
causes anoxia tissue.
of
• �Anoxic damage the endothelial lining causes increased vascular permeability.
to

of
• �Myocardial ischaemia induces release myocardial depressant factor (MDF), which

causes decreased coronary blood flow.
of
• �Cerebral ischaemia causes depression vasomotor centre.

s

• �Normally, vasodepressor material (VDM) produced by spleen and skeletal muscle
i

I
n
f
o
n
i
o
o
inactivated liver. severe hypoxia liver, inactivation VDM takes place inducing
n
f
t
o
leading peripheral vasodilatation.
• �Release TNF
of
• �Hypercoagulability blood
of
Morphologic Changes in Shock
in
• �Morphologic changes shock are due hypoxia resulting degeneration and necro-
to
in
sis various organs.
in
• �Major organs affected are brain, heart, lungs and kidneys. Adrenals, GIT and liver are
also affected.
Hypoxic encephalopathy
1.
• �Neurons more prone hypoxic damage.
to

• �Cytoplasm of affected neurons becomes intensely eosinophilic and the nucleus
pyknotic.
• �Dead and dying nerve cells are replaced by gliosis.
Heart
2.
to
is
• Heart more vulnerable the effects hypoxia than any other organ.
of
• Subepicardial and subendocardial regions show haemorrhage and necrosis.

in

Zonal lesions (contraction bands
• � the myocytes near the intercalated disc) and
be
of
distortion myofilaments may seen.
3.
Lung
Because dual blood supply, lungs are generally not affected by hypovolaemic shock.
of
In septic shock, lungs may manifest with ARDS (shock lung) show the following
or
features:
• �Diffuse alveolar damage
• �Interstitial lymphocytic infiltrate and oedema
of
• �Formation alveolar hyaline membrane, and thickening and fibrosis alveolar
of
septae
of
in
• �Presence microthrombi pulmonary microvasculature
4.
Kidney
to
in
• �Shock may lead irreversible renal injury resulting anuria and death.
is
• �Kidney swollen and may show acute tubular necrosis and brown tubular casts. The
in
latter are seen cases extensive muscle damage due intravascular haemolysis.
to
of
Adrenals
5.
• �Stress response shock releases aldosterone, glucocorticoids and catecholamines.
in
of
• �Active adrenal cells utilize stored lipids for the synthesis steroids.
• �Adrenal haemorrhages may seen severe shock.
be
in
6.
Haemorrhagic gastroenteropathy
• �Multifocal superficial ulcers are seen.
• �Adjoining bowel mucosa oedematous and haemorrhagic.
is
• �Microscopy reveals mucosal and mural infarction.

7. Liver
usually
mottled
• �Liver is enlarged and shows a cut surface.
• �Sections show focal (centrilobular) necrosis and fatty change.
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