Oedema

Question 1

Define edema

Answer 1

• Excessive accumulation of extracellular fluid in the interstitial tissue or body cavity
• Maybe localized or generalized (anasarca

Question 2

Give types of pericardial effusion

Answer 2

Pleural effusion : Accumulation of fluid in pleural cavity

Pericardial effusion :
Accumulation of fluid in the pericardial cavity ,compromise the ability of the heart to beat

Ascites ; Accumulation of fluid in the peritoneal cavity

Question 3

Distribution of fluid between vascular compartment and interstitial space depends on :

Answer 3

• Colloid osmotic pressure : proteins draw water into the intravascular space
• Capillary hydrostatic pressure : forces water out of the vessel
• Interstitial hydrostatic pressure : pushes water into the capillary
• interstitial osmotic pressure : it is too insignificant to cause a change ,in ideal situation s

Question 4

Normal homeostatic depends on

Answer 4

• Intact vessel wall
• Intravascular pressure (hydrostatic pressure) and osmolarity (oncotic pressure ) within physiological ranges
• Changes in vascular volume ,pressure ,protein content or changes in endothelial function affect net movement of water across net movement

Question 5

Classification of edema : 4 pathogenic mechanisms

Answer 5

1. Venous - due to increased intravenous pressure
   * Congestive cardiac failure
   * Constrictive pericarditis
   * Venous obstruction : thrombosis ? compression

*Any cause of fluid retention
+Excessive salt intake with renal insufficiency
+ Cushing syndrome - cortisol causes sodium and fluid retention

Question 6

1.Cardiac edema mechanism

first mechanism of edema

Answer 6

*Congestion from heart failure > increased hydrostatic pressure in the vein

> Decreased renal blood flow from the lest heart failure causes Na+ retention which water back into intravascular space and increase ECF volume

> Heart failure is associated with pulmonary edema and congestion of the liver

Question 7

How to test cardiac edema

Answer 7

*Finger pressure over edematous tissue displaces the interstitial fluid and leaves a finger-shaped depression called pitting edema

Question 8

How to determine venous obstruction

Answer 8

• Unilateral leg edema - thrombus causing venous obstruction resulting in increase in hydrostatic pressure
• Deep vein thrombosis is a serious complication of immobilization and surgery

Question 9

2. Hypoalbuminaemic ( reduced plasma oncotic pressure –Second mechanism of edema

Answer 9

• liver failure eg cirrhosis
• reduced synthesis of albumins > edema
• Protein malnutrition = reduced protein intake
• Increased protein loss
• Protein losing enteropathy
• Nephrotic syndrome (protein is lost in urine)

Question 10

3. Hepatic edema

the third mechanism of edema

Answer 10

• obstruction of the portal venous system
• Manifested by ascites
• The diseased liver has decreased synthesis of albumin > worsen the edema

Question 11

Lymphatic edema

aetiology of edema

Answer 11

*Tissue drains of fluid by lymphatic ,if obstructed results in edema

-Neoplastic ; infiltration of the lymphatic vessels by tumour eg in breast carcinoma(peau D orange ( looks like orange ) .
edema of skin

Question 12

Aetiology of edema :

Disruption of the lyphatic system can lead to edema

Answer 12

1.Post surgical eg axillary lymph node dissection for breast cancer ,rare event

2.Post irradiation
firm brawny edema ,non pittity

3. Obstruction of lymphatic drainage by filarial parasites( eg wuchecheria bancrofti)
   * Lymph node fibrosis in the inguinal region > edema of genetalia and lower limbs - elephantiasis

Question 13

4. Inflammatory - Increased vascular permeability

fourth mechanism

Answer 13

• Endothelial cells separate - chemical mediators
• Protein - rich fluid leaks into interstitium > local swelling
• Dilutes toxins
• fibrin localize damage
• immunoglobulins ,neutrophils and complement neutralize toxins and bacteria
• associated with pain and redness

Question 14

Acute inflammatory edema

Answer 14

• Exudate at site of inflammation
• Due to increase vascular permeability and increase in hydrostatic pressure
• Hyperemia

Question 15

Allergic / hypersensitivity edema = angioedema

5th mechanism

Answer 15

*Form of inflammatory edema associated with allergy eg drug ,food
*often seen in skin and mucous membrane
>Increase in vascular permeability and histamine release
> edema of eyelids , lips ,tongue ,larynx and lungs

Question 16

Clinical features of generalized edema

Answer 16

1. Evident after accumulation of at least 5 liters of extra fluid
   * Best way to measure generalized edema is weight patient
   * Gravitational depends on position of patient
   * can be demonstrated by pitting on pressure, takes 1-2 min to recover normal shape of skin

Question 17

types of edema fluid

Answer 17

1. transudate
   * Usually straw - coloured often blood stained
   * no cells
   * protein free fluid
   * intact vessel wall
2. Exudate
   * High protein turbid fluid
   * contain inflammatory cells
   * found from damaged vessel wall
   * fibrin clot present

Question 18

3 types of brain edema

Answer 18

1.3 Vasogenic edema

• BBB is disrupted
• with increased vascular permeability
• Accumulation of fluid in the extracellular space
• associated with tumor

2. Cytotoxic edema
   * Increase in intracellular edema due to neuronal , glial and endothelial membrane damage
   * Brain cells become waterlogged eg cloudy swelling ischemia
3. Interstitial edema
   * In non-communicating hydrocephalus where there is obstruction of flow from the ventricles ,CSF permeates through the ependymal lining of the ventricles into surrounding white matter

Question 19

Morphology of brain edema

Answer 19

• flattened gyri
• Narrowed sulci
• soft with fluid dripping
• swelling of the brain leads to raised ICP ,if severe l> brain herniation
• can be diagosed by finding papilledema

Question 20

Pulmonary edema

type of edema

Answer 20

1. Seen in
   * left ventricular failure ,lung infection ,diffuse alveolar damage ,aspiration pneumonia ,O2 toxicity and hypersensitiity reactions
2. the lungs are congsted and weigh 32 –3 x their normal weight
3. Edema fluid is high in protein content
4. Decreased lung volume > breathless and cyanosed
5. fluid accumulates in alveolar spaces
6. fluid in spaces - > low gaseous exchanges >capillary becomes hypoxic with increased permeability and protein escapes from the vessel

clinically : lungs sound as if air bubbling through water

Question 21

Renal edema

types of edema

Answer 21

• sodium and water retention > increased hydrostatic pressure
• Nephrotic syndrome - low serum albumin
• Increased vascular permeability
• Increased vascular permeability
• Starts in tissues with loose connective tissue matrix eg peri - orbital