What is oedema

What is oedema?

Oedema signifies increased fluid in the intercellular tissue spaces and/or body cavities. It is clinically evident when there is an excess of fluid by 10 percent.

Anasarca implies generalized oedema. It is often severe producing marked swelling of the subcutaneous tissue. Ascites implies that there is increased fluid collection in the peritoneal cavity and hydropericardium implies increased fluid accumulation in pericardial cavity.

Classification

Types of oedema are classified as belows:

1. On extent of involvement: Localized oedema and generalized oedema.

2. On nature of fluid: Inflammatory oedema and non-inflammatory oedema.

3. On nature of fluid: Exudate (Inflammatory oedema) and transudate (Non-inflammatory oedema).

4. On clinical basis: Pitting oedema and non-pitting oedema.

Localized oedema types:

1. Inflammatory oedema (Exudate)

2. Pulmonary oedema

3. Ascites, pericardial effusion, peritoneal effusion

4. Odema of peripheral venous obstruction

5. Lymphoedema (it occurs in lymphatic obstruction)

6. Others

i) Cardiac oedema

ii) Renal oedema

iii) Hepatic oedema

iv) Nutritional oedema (Famine oedema)

Exudate: Exudate is formed in inflammation and is rich in protein due to increased vascular permeability. Specific gravity is usually over 1020. Increased capillary hydrostatic pressure also plays role.

Transudate: Transudate is formed in non-inflammatory oedema. Transudate is protein poor fluid with a specific gravity usually below 1012 and is formed due to haemodynamic derangements.

Other oedemas: Some other oedemas also occurred which are given below:

A. Oedema in normal people: Ankle oedema may occur in people whose work entails long period of standing.

B. Oedema in pregnancy: Transudate is formed (1) Normal pregnancy - In some pregnant women ankle oedema and occasionally generalized oedema occurs. (2) Preeclampsia – Oedema is accompanied by proteinuria and hypertension. (3) White leg in pregnancy – oedema of leg due to thrombophlebitis.

C. Oedema in hypersensitivity reactions (Allergic oedema): Exudate is formed due to increased vascular permeability. (A) Localized – 1.Type I hypersensitivity-urticaria, angioedema, 2. Type III immune complex hypersensitivity-urticaria (B) Generalized in anaphylaxis.

D. Angioedema: Exudate is formed. Oedema involves dermis, subcutaneous tissue and mucous membranes. Recurrent attacks occur. Causes – (1) Type I hypersensitivity – atopic allergy, (2) Type III hypersensitivity in collagen vascular diseases, (3) Physical and chemical agents,(4) Hereditary angioedema and (5) Unknown.

E. Oedema due to steroids: Transudate is formed due to sodium and water retention. Causes: (1) Administrations of glucocorticoids or ACTH, (2) Cushing’s syndrome.

F. Cyclical or periodic oedema: Cyclical oedema is more common in women and is usually related to menstrual cycle. It may stop after menopause. It is usually localized but may be generalized. The cause is unknown but both hereditary factors and allergy have been blamed. There is increase in vascular permeability.

G. Idiopathic oedema of women: Oedema occurs in women between 30 and 45 years on the face, hands and legs during the day. It diminishes during night.

H. Oedema in protein-losing Enteropathy: Hypoproteinaemia is the cause of this uncommon condition.

I. Oedema of brain: In brain, oedema may be loacalized about focal lesions like neoplasms, abscess, trauma or generalized involving whole brain as for example in hypertensive crisis, encephalitis, trauma. It is a fatal condition.