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EDEMAEDEMA : presence of : presence of excess fluid in the excess fluid in the

body tissuesbody tissues

A.A. Intracellular Edema Intracellular Edema aa.. depression of the metabolic depression of the metabolic

systems systems of the tissuesof the tissues

b.b. lack of adequate nutrition to the lack of adequate nutrition to the cellscells

A. Extracellular Edema

a. abnormal leakage of fluid from the plasma to the interstitial spaces across the capillariesfailure of the lymphatics to return fluid from the

interstitium back into the blood

The most common clinical cause of interstitial fluid accumulation is excessive capillary fluid filtration

Factors That Can Increase Capillary Filtration

1. Filtration Coefficient – product of permeability and surface area of the capillaries (Kf)

2. Capillary Hydrostatic Pressure (Pc)

3. Interstitial Fluid hydrostatic Pressure (Pif)

4. Capillary Plasma colloid Osmotic Pressure (iic)

5. Interstitial Fluid Colloid Osmotic Pressure (iiif)

Filtration = Kf x ( Pc – Pif – iic + iiif )

Major Factors that cause Increased Capillary Filtration of Fluid and Protein into

the Interstitium:

1. Increased capillary Hydrostatic Pressure

2. Decreased Plasma Colloid Osmotic Pressure

3. Increased Capillary Permeability

Summary of Causes of Extracellular Edema

Increased capillary pressure

A. Excessive kidney retention of salt and water1. Acute and chronic kidney failure

2. Mineralocorticoid excess

B. High venous pressure 1. Heart failure

2. Venous obstruction

3. Failure of venous pump

a) paralysis of muscles

b) immobilized parts of body

c) Failure of venous valves

C. Decreased arteriolar resistance

1. Excessive body heat

2. Insufficiency of sympathetic nervous system

3. Vasodilator drugs

II. Decreased plasma protein

A. Loss of proteins in urine (nephrotic syndrome)

B. Loss of protein from denuded skin areas1. Burns2. Wounds

C.Failure to produce proteins1. Liver disease

2. Serious protein or caloric malnutrition

III. Increased capillary permeabilityA. Immune reactions that cause release of histamine

B. Toxins

C. Bacterial infections

D. Vitamin deficiency, especially vitamin C

E. Prolonged ischemia

F. Burns

IV. Blockage of lymph return

A. Cancer

B. Infections (filarial nematodes)

C. Surgery

D. Congenital absence or abnormality of lymphatic vessels

Safety Factors That Prevent Edema

1. The safety factors caused by low tissue compliance ( -3mmHg )

2. The safety factor caused by increased lymph flow ( 7 mmHg )

3. The safety factor caused by washdown of proteins from the interstitial spaces ( 7 mmHg )

DAILY INTAKE AND OUTPUT OF WATER (in ml/day)________ Normal Prolonged

Heavy Exercise

Intake Fluids ingested 2100 ? From metabolism 200 200 Total intake ?

Output Insensible – Skin 350 350 Insensible - Lungs 350 650 Sweat 100 5000 Feces 100 100 Urine 1400 500

Total output 2300 6600

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