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Hemodynamic disorders
Fatima Obeidat, MD
Faculty of medicine
Jordan University
1. Hyperemia and congestion
- Both indicate a local increased volume of
blood in a particular tissue
I. Hyperemia
- Is an active process
- Results from augmented blood flow due to arteriolar
dilation such as:
a. At sites of inflammation or
b. In skeletal muscle during exercise
- The affected tissue is redder than normal because of
engorgement with oxygenated blood
II. Congestion
- Is a passive process
- Results from impaired venous return out of a
tissue
- It may occur
a. Systematically, as in cardiac failure,
b. or it may be local, resulting from an isolated
venous obstruction
- The tissue in congestion has a blue-red color
(cyanosis), especially as worsening congestion
leads to accumulation of deoxygenated
hemoglobin in the affected tissue
- Congestion of capillary beds leads to
development of edema; so that congestion and
edema commonly occur together
morphology
1. Acute pulmonary congestion is characterized by:
a. alveolar capillaries engorged with blood
b. There may also be alveolar septal edema and focal
minute alveolar hemorrhage
2. Chronic pulmonary congestion is characterized by:
a. Alveolar septae become thickened and fibrotic
b. Hemosiderin laden macrophages are seen in alveoli
called heart failure cells
3. In acute hepatic congestion
a. The central vein and sinusoids are distended with
blood
b. May be central hepatocyte degeneration
c. The periportal hepatocytes are better oxygenated
because of their proximity to hepatic arterioles
4. Chronic hepatic congestion
- The central regions of hepatic lobules are red-brown and
slightly depressed because of loss of cells
- Microscopically: there is centrilobular necrosis with
hepatocyte dropping, hemorrhage and hemisderin-laden
macrophages
2. Edema
- Approximately 60% of body weight is water, two-thirds
of which is intracellular and the remainder is
extracellular, mostly as interstitial fluid
- Only 5% of total body water is in blood plasma
- The term edema means accumulation of interstitial
fluid within tissues.
- Hydrothorax : is Fluid collection in the pleural cavity
- Hydropericardium : Fluid collection in the pericardium
- Hydroperitoneum or ascitis : Is fluid collection and in
he peritoneum
- Anasarca: Severe and generalized edema with
profound subcutaneous tissue swelling
• Fluid movement between the vascular and the
interstitial spaces is governed by two opposing
forces
1. The vascular hydrostatic pressure
2. The colloid osmotic pressure produced by
plasma proteins
Normally, the outflow of fluid produced by
hydrostatic pressure at the arteriolar end of the
microcirculation is balanced by inflow due to the
slightly elevated osmotic pressure at the venular
end
- ; hence there is only a small net outflow of fluid
into the interstitial space, which is drained by
lymphatic vessels
-
- The edema fluid produced by increased hydrostatic
pressure or reduced intravascular colloid pressure , is
a protein poor called transudate with specific gravity
less than 1.012
- In contrast, the inflammatory edema is protein rich and
specific gravity greater than 1.020 (exudate)
Causes of non-inflammatory edema are:
Increased hydrostatic pressure
II. Reduced plasma osmotic pressure
III. Lymphatic obstruction
IV. Sodium retention
I.
I. Increased hydrostatic pressure
A. Impaired venous return
1. Local increases in intravascular pressure can result
from
i. Impaired venous return ;for example due to deep
venous thrombosis in the lower extremity which can
cause edema restricted to the distal portion of the
affected leg
ii. External compression by a mass
iii. Lower extremity inactivity with prolonged dependency
2. Generalized increase in venous pressure, with
resultant systemic edema occur most commonly in
congestive heart failure
- Factors that increase venous hydrostatic pressure in
congestive heart failure are
- The reduced cardiac output leads to hypoperfusion of
the kidneys, triggering the renin-angiotensin –
aldosterone axis and inducing sodium and water
retention (secondary hyperaldosteronism)
- Inpatients with failing heart , the heart cannotb
increase its cardiac output in response to the
compensatory increases in blood volume ;instead a
vicious circle of fluid retention , increased venous
hydrostatic pressure and worsening edema ensues
• Patients need salt restriction or treatment with
diuretics or aldosterone antagonists
Other causes of impaired venous return
- Constrictive pericarditis
B. Arteriolar dilation such as heat
II. Reduced plasma osmotic pressure
- Albumin accounts for almost half of the total
plasma proteins
- Conditions in which albumin is either lost from
circulation or synthesized in an inadequate
amounts are common causes of reduced
oncotic pressure
- Reduced osmotic pressure occurs in:
A. Nephrotic syndrome
- In which damaged glomerular capillary walls become
leaky, leading to loss of albumin
B. Liver cirrhosis—reduced albumin synthesis
C. Protein malnutrition
D. Protein losing gastroenteropathy
III. Lymphatic obstruction
- Impaired lymphatic drainage and consequent
lymphedema is usually localized
- Causes
A. Inflammation of lymphatics such as parasitic infection
filariasis which causes inguinal lymphatic and lymph
node fibrosis-----the resultant edema of the external
genitalia and lower limbs can be so massive and
called elephantiasis
B. Neoplastic: such as in breast cancer
- infiltration and obstruction of superficial
lymphatics by cancer cells can cause edema of
the overlying skin called peau d’orange
appearance
C. Postsurgical:
- Removal of axillary lymph nodes as part of
surgical treatment of breast cancer will disrupt
the lymphatic drainage causing severe
lymphedema of the arm
D. Postradiation
- Radiotherapy causes fibrosis of lymphatics and
lymph nodes and impair lymphatic drainage
Morphology
- Edema is easily recognized on gross inspection
- Microscopic examination shows clearing and
separation of the extracellular matrix elements
- Although any tissue can be involved, edema
most commonly is encountered in subcutaneous
tissues, lung,and brain
- Subcutaneous tissue edema can be diffuse but
usually accumulates preferntially in parts of the
body positioned the greatest distance below the
heart where the hydrostatic pressure are the
highest
- Edema is pronounced in the legs with standing
and sacrum with recumbency; so called
dependent edema
- Finger pressure over the edematous subcutaneous
tissue displaces the interstitial fluid ,leaving a
finger-shaped depression; this appearance is
called pitting edema
- Edema due to nephrotic syndrome often manifests
first in loose connective tissues (the eyelids
causing perorbital edema
2. With pulmonary edema, the lungs often are two to
three times their normal weight and sectioning reveals
frothy sometimes blood tinged fluid consisting of a
mixture of air, edema fluid and extravasated RBCs
3. Brain edema can be localized due to abscess or tumor
Or generalized
- If generalized, the sulci are narrowed and the gyri are
swollen and flattened against the skull
Clinical correlation of edema
- The effects of edema vary, ranging from merely
annoying to fatal
-Subcutaneous edema
a. Is important to recognize because it signals potential
underlying cardiac or renal diseases
b. When significant, it also can impair wound healing or
the clearance of infection
Pulmonary edema
- Is commonly seen in left ventricular heart failure but may
occur in renal failure
- It can cause dearth by interfering with normal ventilatory
function
Brain edema
- Is life threatening ,if the swelling is severe , the brain can
herniate