Pathogenic Classification of Edema

Study Notes

Edema Overview

Abnormal accumulation of fluid in interstitial spaces and body cavities, resulting in conditions like hydrothorax, hydropericardium, and hydroperitoneum (ascites).

Types of Edema

Anasarca: Severe generalized edema causing extensive subcutaneous swelling.
Pitting Edema: Indentation remains after pressing the swollen area; associated with fluid excess due to increased venous hydrostatic pressure from conditions like heart failure and venous obstruction.
Non-Pitting Edema: Fluid is bound in the interstitium; potential causes include myxedema from hypothyroidism and lymphatic system blockages.

Fluid Dynamics

Fluid balance is maintained by the interplay of vascular hydrostatic pressure and plasma colloid osmotic pressure.
Lymphatic system is responsible for draining excess interstitial fluid.

Edema Types and Characteristics

Transudate: Non-inflammatory, protein-poor fluid with a specific gravity below 1.012; occurs from hydrodynamic shifts.
Exudate: Inflammatory fluid with increased vascular permeability, typically with a specific gravity over 1.020.
Movement of fluid is influenced by osmotic gradients, hydrostatic pressure, and oncotic pressure.

Pathophysiological Considerations

Increased hydrostatic pressure at the arterial end leads to vasoconstriction and potential hypertrophy of vessel walls over time.

Brain and Pulmonary Edema

Brain Edema: Caused by tumors, intoxication, or inflammation; can lead to fatal herniation and results from increased extracellular fluid due to vascular permeability and obstruction of cerebrospinal fluid flow.
Cytotoxic Brain Edema: Increased intracellular fluid linked to ischemic or hypoxic injuries.
Pulmonary Edema: Typically results from left-sided heart failure, characterized by foamy fluid affecting oxygenation.

Causes of Edema

General causes include:
- Increased capillary pressure
- Decreased colloid osmotic pressure
- Increased capillary permeability
- Blocked lymphatic drainage
Non-inflammatory edema causes include:
- Increased hydrostatic pressure due to conditions like congestive heart failure
- Reduced plasma osmolality from nephritic syndromes or liver cirrhosis
- Sodium retention from excessive salt intake and renal insufficiency.

Specific Causes of Non-Inflammatory Edema

Increased hydrostatic pressure may result from conditions such as constrictive pericarditis, venous obstruction, and prolonged inactivity.
Reduced plasma osmotic pressure is commonly associated with nephrotic syndrome, liver cirrhosis, and severe malnutrition.
Sodium retention can be triggered by renal hypoperfusion and prolonged excessive dietary intake.

Description

Test your knowledge on edema with these flashcards covering definitions and related terms. Learn about the mechanisms and specific types of edema, including hydroperitoneum. Perfect for medical students and healthcare professionals.