Download Lec: 1 Dr.Methaq Mueen Hemodynamic disorders Hemo means

Lec: 1
Dr.Methaq Mueen
Hemodynamic disorders
Hemo means blood, dynamic means movement.
Haemodynamic disturbance = circulatory disturbance.
The health of cells and tissue depends not only on an intact circulation to deliver
O2 and remove wastes but also on normal fluid homeostasis.
Normal homeostasis means:
1- Maintenance of vessel wall integrity.
2- Maintenance of intravascular pressure and osmolarity within certain
physiologic ranges.
3-Maintaining blood as a liquid until such time as injury necessitates clot
formation.
*Changes in: vascular volume, pressure or protein content or
alteration in endothelial function affect the net movement of water across the
vascular wall "hemodynamic disturbance" leading to:
Edema: increase fluid in interstitial spaces, serous cavities or pulmonary alveoli.
Thrombosis: formation of a solid mass of blood elements in the CVS during life .
Embolism: migrating thrombus, fat and air carried by the blood to sites
distant from their point of origin
Hemorrhag: escape of blood from CVS.
shock: hypoperfusion due to inadequate circulating blood volume.
The efficiency of the circulatory system is based on normal fluid
dynamics of blood. Deviations from the normal state have several
consequences.
EDEMA:
Edema in Greek means"swelling"
*60% of body weight is water.
*Two third of which is intracellular.
*one third is extra cellular mostly as interstitial fluid.
*only 5% of total body water is in blood plasma.
EDEMA: is increase fluid in interstitial space.
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Increase fluid in pleural cavity is called hydrothorax or pleural effusion,
in pericardium: hydropericardium or pericardial effusion , in peritoneum
hydroperitoneum (ascites).
Anasarca: is a sever and generalized edema with profound subcutaneous tissue
swelling.
*Pathophysiology of edema: vascular hydrostatic pressure &plasma colloid
osmotic pressure control the movement of fluid between vascular & interstitial
spaces .The outflow of fluid from arteriolar end is balanced by the inflow at the
venular end and small amount drain by lymphatics.
The pathophysiologic categories of edema
1-Inflammatory edema: due to effect of inflammatory mediators that
increase vascular permeability. Edematous fluid is protein rich
(exudates) with specific gravity that is usually over 1.012.
2-The non inflammatory causes of edema:
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The edema fluid occurring in hydrodynamic derangements is typically
a protein –poor ( transudates )With specific gravity that is
below1.012.
Factors regulate edema(causes of edema):
1- Increase capillary hydrostatic pressure.
2- Decrease colloid osmotic pressure.
3- Effect of inflammatory mediators on vascular permeability.
4- Lymphatic obstruction can impair fluid drainage &cause edema.
5- Na &water retention.
1. Increased hydrostatic pressure:
*Localized increase in venous pressure e.g. (deep venous thrombosis DVT) with
edema of the affected limb.
*Generalized increase in venous pressure with systemic edema occur in congestive
heart failure in which reduced cardiac output causes reduced renal perfusion &
trigger of rennin angiotensin aldosterone axis causing sodium & water retention
by kidney in order to increase intravascular volume & improve cardiac output &
renal perfusion .This extra fluid load only increased venous pressure & edema
.Unless cardiac output restored or renal fluid retention reduced (e.g salt
restriction , diuretics &/or aldosteron antagonists),vicious cycle of renal fluid
retention & worsening edema result.
Other causes of increased hydrostatic pressure are:
Constrictive pericarditis.
Venous compression .
Thrombosis.
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2. Reduced plasma osmotic pressure:
Result from:
 Increased loss of albumin as in nephrotic syndrome and protein losing
enteropathy like chronic inflammatory bowel disease.
 Reduced protein synthesis as in cirrhosis, malnutrition.
Reduced plasma osmotic pressure causes edema, reduced intravascular volume
&secondary aldosteronism &add more edema .
3. Lymphatic obstruction: Usually localized, can result from:
(1) Inflammatory obstruction e.g. filariasis which causes lymphatic obstruction&
lymph node fibrosis in inguinal region leading to edema of genitalia& lower limb
(elephantiasis).
(2) Neoplastic obstruction: Cancer of breast treated by surgery or irradiation with
resection of lymphatic & scarring; there is edema of the arm.
(3) In CA breast, infiltration & obstruction of superficial lymphatics will cause edema
of skin (peau-de-orange) due to accentuation of depression in the skin at site of
hair follicles.
 Lymphatic edema differs from other forms of edema in its high protein
content ,since lymph is the vehicle by which proteins and interstitial cells
are returned to the circulation. The increased protein concentration may
be a fibrogenic stimulus in the formation of dermal fibrosis in chronic
edema (indurated edema)so it become non pitting.
Na &water retention:
These are contributory factors in several forms of edema or it may also be a primary
cause of edema.
Causes: it occur with any acute reduction of renal function e.g.poststreptococcal
glomerulonephritis and acute renal failure
Mechanism of causing edema in Na &water retention :
1-expantion of intravascular fluid volume
2-decreasd vascular colloid osmotic pressure
Morphology of the edema:
Grossly: edema is most easily recognized grossly.
Microscopically: Clearing & separation of extra cellular matrix.
Any organ or tissue in the body may be involved, edema is most commonly occur in
SCT, lung and brain .sever generalized edema is also called anasarca.
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Subcutaneous edema
May have different distributions depending on the cause
It is of two types (dependent & independent) Edema.
 Dependent Edema: (Edema with gravity)
I. Edema of cardiac failure: this is mainly in the legs in standing patient & in the
sacrum in recumbent patient.
II. Edema of renal cause: this is more severe than cardiac edema & affect all parts of
the body equally, (first periorbital edema).
 Dependent edema also called Pitting Edema (pressure by fingers on
edematous area will result in depressed area).
 Independent Edema:(Edema against gravity)
Edema of fingers in patient with Preeclampsia.
Classification of oedema:
1) According to pathophysiological mechanism:
a) Transudate (low protein content)
b) Exudate (high protein content)
2) According to location:
a) Localized
b) Generalized
3) According to clinical finding:
a) Pitting
b) Non-pitting.
Examples:
 Localised: Venous edema, Lymphatic edema, allergy/angioedema,
inflammation.
 Generalised: Cardiac edema, Hepatic edema, renal edema, Endocrine edema.
 Pitting: due to cardiac & renal causes, liver disease.
 Non-pitting: Myxoedema, Elephantiasis, Angioneurotic.
 Pulmonary edema
Seen in:
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(1) Left sided heart failure (dependent distribution in lung)
(2) Respiratory distress syndrome.
(3) Pulmonary infection.
(4) Hypersensitivity reaction.
The lung is 2-3 times their normal weight, cut section frothy, blood tinged
Fluid represent mixture of air, edematous fluid & extravasated RBCs.
 Edema of brain
*Localized e.g. abscess, neoplasm & trauma.
*Generalized e.g. encephalitis, hypertension crises, venous outflow obstruction &
trauma.
Gross: Swollen with narrowed sulci & distended gyri.
Clinical correlations: (EFFECTS OF EDEMA)
a. Subcutaneous edema in cardiac & renal failure can impair wound healing or
clearance of infection.
b. Pulmonary edema can cause death by interfering with normal ventilatory function;
due to:
(1) Fluid collection in alveolar space& impaired oxygen diffusion.
(2) Edematous fluid in alveolar spaces is favorable environment for bacterial
infection.
c. Brain edema if severe, brain herniated through foramen magnum or brainstem
vascular supply compress & both injured the medullary centers & cause death.
Hyperemia & Congestion
Both terms indicate a local increased volume of blood in a particular tissue.
But there are many differences between them.
*Hyperemia: is an active process from augmented tissue inflow due to arteriolar
dilatation &is divided into:
1- Localized hyperemia.
2- General hyperemia.
*Localized increase of blood flow could be
1. Physiological e.g. flushing, exercise, after meal.
2. Pathological e.g. site of inflammation.
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*Generalized increase of blood flow could be:
1. Physiological e.g. hot weather.
2. Pathological: e.g.:
 Fever
 Hyperthyroidism due to increase metabolic rate
 Arteriovenous shunt in liver failure due to the accumulation of the
vasodilator metabolites in the blood because the liver is incapable to
detoxificate them.
Hyperemia & Congestion
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