Tishk International UniversityScience FacultyMedical Analysis Department

Pathology

Fourth Grade- Spring Semester 2020-2021

Hemodynamic disorders -1, Edema

Dr. Jalal A. JalalAssistant Professor of Pathology

Edema

Objectives:

To define the term edema.

To explain how the process of edema occurs.

To discuss the clinical significance of edema.

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Edema

• Approximately 60% of total body weight is water.

• Two thirds of the body's water is intracellular,

• The remainder is in extracellular compartments, mostlythe interstitium (or third space) that lies between cells;

• Only about 5% of total body water is in blood plasma.

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• The movement of water and salts between theintravascular and interstitial spaces is controlledprimarily by the opposing effect of

• Vascular hydrostatic pressure, and

• Plasma colloid osmotic pressure.

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• Normally the outflow of fluid from the arteriolar end ofthe microcirculation into the interstitium is nearlybalanced by inflow at the venular end.

• A small residual amount of fluid may be left in theinterstitium and is drained by the lymphatic vessels,ultimately returning to the bloodstream via the thoracicduct.

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• Either increased capillary pressure or diminishedcolloid osmotic pressure can result in increasedinterstitial fluid.

• If the movement of water into tissues (or bodycavities) exceeds lymphatic drainage, fluidaccumulates.

• An abnormal increase in interstitial fluid withintissues and or body cavities is called edema.

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• Fluid collections in the different body cavities arevariously designated as:

• Hydrothorax, or plueral effusion

• Hydropericardium, or pericardial effusion

• Hydroperitoneum or ascites

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Pleural effusion

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Severe Ascites due to Rt. sided heart failure

secondary to lung disease (note cyanosis).

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Severe Ascites due

to liver cirrhosis

(note jaundice)

Ascites

• Edema caused by increased hydrostatic pressure orreduced plasma protein is typically a protein- poor fluidcalled a transudate.

• Edema fluid of this type is seen in patients sufferingfrom heart failure, renal failure, hepatic failure, andmalnutrition.

• In contrast, inflammatory edema is a protein-richexudate that is a result of increased vascularpermeability.

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Types of edema fluid

• Transudate: protein poor (1.020 results from increased vascularpermeability caused by inflammation.

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Pathophysiologic Categories of Edema

1. INCREASED HYDROSTATIC PRESSURE:

Congestive heart failure.

Constrictive pericarditis.

Venous obstruction or compression:

Thrombosis.

External pressure (e.g., mass).

Lower extremity inactivity with prolongeddependency.

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2. REDUCED PLASMA OSMOTIC PRESSURE (HYPOPROTEINEMIA):

Protein-losing glomerulopathies (nephrotic syndrome)

Liver cirrhosis (ascites)

Malnutrition

Protein-losing gastroenteropathy

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3. LYMPHATIC OBSTRUCTION:

Inflammatory

Neoplastic

Postsurgical

Postirradiation

Parasitic

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4. SODIUM RETENTION:

• Excessive salt intake with renal insufficiency.

• Increased tubular reabsorption of sodium.

• Renal hypoperfusion.

• Increased renin-angiotensin-aldosterone secretion.

5. INFLAMMATION:

• Acute inflammation.

• Chronic inflammation.

• Angiogenesis.

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Morphology

1. Subcutaneous edema

• In most cases the distribution is influenced bygravity and is termed dependent edema (e.g., thelegs when standing, the sacrum whenrecumbent).

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Pitting edema, Ankle region.

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Morphology. ….

2. Edema as a result of renal dysfunction can affect allparts of the body.

• It often initially manifests in tissues with looseconnective tissue matrix, such as the eyelids; so

• periorbital edema is a characteristic finding in severerenal disease.

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Periorbital edema in Nephrotic Syndrome

Morphology….

3. Pulmonary edema,

• the lungs are often two to three times their normal weight, and

• sectioning yields frothy, blood-tinged fluid—a mixture of air, edema, and extravasated red cells.

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Pulmonary edema,

Sectioning yields frothy,

blood-tinged fluid—a

mixture of air, edema &

extravasated red cells.

Microscopically there’s

vascular congestion with

alveoli filled with smooth

pinkish transudative fluid .

Morphology. ….

4. Brain edema

• can be localized or generalized depending on thenature and extent of the pathologic process or injury.

• With generalized brain edema the brain is grosslyswollen with narrowed sulci; distended gyri showevidence of compression against the unyielding skull.

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Clinical Significance

• Subcutaneous tissue edema

1. It signals potential underlying cardiac or renal disease.

2. However, when significant, it can also impair wound healing or the clearance of infection.

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• Pulmonary edema

• is a common clinical problem that is most frequentlyseen in the setting of left ventricular failure; it’ssignificance:

1. Fluid collect in the alveolar septa around capillariesand impede oxygen diffusion.

2. Edema fluid in the alveolar spaces also creates afavorable environment for bacterial infection.

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Clinical Significance…..

• Brain edema

• is life-threatening; if severe, brain substance canherniate (extrude) through the foramen magnum,or the brain stem vascular supply can becompressed.

• Either condition can injure the medullary centersand cause death.

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Summary

• Edema is extravasation of fluid from vessels intointerstitial spaces; the fluid may be protein poor(transudate) or may be protein rich (exudate).

• Edema results from any of the following conditions:

• Increased hydrostatic pressure

• Decreased colloid osmotic pressure

• Lymphatic obstruction

• Primary renal sodium retention

• Increased vascular permeability

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