Edema and Effusions

Flashcards about Edema and Effusions, covering definitions, types, pathogenesis, and specific examples like renal, cardiac, and cirrhotic edema.

Edema

Abnormal and excessive accumulation of fluid in the interstitial space and serous cavity.

Effusions

Fluid accumulation in pleural, pericardial, and peritoneal cavities (ascites).

Types of Edema

Localized or generalized (anasarca); pitting or non-pitting; transudate or exudate.

Normal Tissue Fluid Regulation

Constant push and pull of fluid across capillary wall, regulated by hydrostatic and oncotic pressure.

Pathogenesis of Edema

Imbalance between hydrostatic and oncotic pressure or lymphatic obstruction.

Five Main Causes of Edema

Increased hydrostatic pressure, decreased oncotic pressure, lymphatic obstruction, inflammation, sodium retention.

Increased Hydrostatic Pressure - Causes

Impaired venous outflow (thrombosis, varicose veins) or systemic (CCF).

Decreased Oncotic Pressure - Causes

Massive protein loss (nephrotic syndrome), decreased synthesis (liver cirrhosis), decreased intake (malnutrition).

Lymphatic Obstruction - Causes

Inflammatory (filariasis), neoplastic, surgical removal, Milroy’s disease (hereditary).

Inflammation and Edema

Endothelial damage leads to increased permeability of protein-rich fluid into tissue spaces, forming exudate.

Sodium, Water Retention and Edema

Na+ retention leads to water retention, increasing hydrostatic pressure and decreasing oncotic pressure (dilutional).

Transudate

Non-inflammatory, Sp. Gr. <1012, Protein < 3g/dL, Less cells, LDH – Low

Exudate

Inflammatory, Endothelial damage, Sp. Gr. >1020, Protein > 3g/dL, More cells, LDH – High

Renal Edema - Types

Nephrotic (massive proteinuria) and nephritic (decreased GFR leading to Na+ water retention).

Cardiac Edema - Mechanisms

Decreased cardiac output leading to increased venous stasis or decreased renal perfusion and activation of RA axis.

Cirrhotic Edema - Mechanisms

Decreased protein synthesis and increased resistance to portal circulation (portal hypertension).

Morphology of Edema

Subcutaneous tissue (dependent, pitting), lungs (heavy, frothy fluid), brain (narrowed sulci, distended gyri).

Pleural Effusion

Fluid in the pleural space.

Pericardial Effusion

Fluid in the pericardial space.

Ascites

Fluid in the peritoneal space.