Edema, Hyperemia and Congestion

Cardiovascular disease• Most important cause of morbidity and

mortality in developed nations

• In US, 81 million affected in 2005, causing 35 to 40% of deaths

• Components of cardiovascular system include Heart Vessels Blood

• Water, salts, proteins, clotting factors, cells

Blood• Hemodynamics

Edema• Water build-up in interstitial spaces and cavities• Hydrodynamic transudate is dilute, protein-poor• Inflammatory exudate is concentrated, protein rich

Hyperemia• Acute, actively increased blood flow—arteriole dilation,

increased heart rate– Tissues look red (erythema)

Congestion• Chronic, passively reduced outflow—venule dilation

– Tissues look pale or blue (cyanosis)

Shock• Circulatory failure

Fluids—water

0 20 40 60 80 100

total water

intracellular

interstitial

intravascular

Percentage lean body mass

Factors affecting intravascular and interstitial water movement

• Concentration of solutes Albumin and other proteins (huge difference) Sodium and other ions (small difference)

• Hydrostatic pressure Higher on arteriolar side Lower on venular side Lowest in interstitium

• Blood volume decreased b.p. Water intake/deprivation Water loss from skin or gut

• Perspiration, vomiting, diarrhea Blood loss; acute hemorrhage

Fluid transit

Edema• Localized or generalized accumulation of fluid in

interstitial spaces Anasarca: severe, generalized edema

• ana = throughout, sark = flesh• Most commonly used to describe fetal or neonatal whole-

body, subcutaneous swelling

• Effusions into body cavities Hydrothorax: within thorax, around lungs; also pleural

effusion Hydropericardium: Fluid in the pericardial sac Hydroperitoneum or ascites: Fluid in the peritoneal

cavity

• Extravasate: (v.) to move out of the vasculature

Responses to edema

• Skin:swells according to elasticity dependent edema: distribution affected by

gravity (ankles, sacrum) dependent = hanging down in this context

• Brain: compresses without room to swell

• Lung: alveoli fill preventing gas exchange

Appearance of edema

• Swollen tissues (not cells—fluid is outside the cells)

• Heavy tissues

• Wet tissues

• Widening of fascial planes or interlobular septa

• Filled cavities

Causes of edema• Increased hydrostatic pressure

Focal impairment—deep vein thrombosis Generalized impairment—right heart failure

• Decreased plasma osmotic pressure Hypoproteinemia

• Decreased protein synthesis—serum albumin• Increased protein loss to nephrotic syndrome

• Sodium (and water) retention• Increased capillary permeability

• inflammation or injury (burns)

• Lymphatic obstruction• Filariasis, breast carcinoma

Appearance and causes of hyperemia

• Increased flow of blood into tissue• Local process of arteriole dilation greater

than venule dilation• Appearance of blood flow is RED• Normal physiological examples:

Exercise Blushing Erection Inflammatory response (rubor)

• Small contribution to edema

Congestion

• Impaired venous outflow from tissue

• Local increases in venous pressure

• Central congestive heart disease increases diastolic (venous) b.p.

• Right-side failure congests portal drainage, liver, generalized edema

• Left-side failure congests pulmonary drainage, lungs, hypoxemia

Congestive heart failure• Right side failure—volume backs up behind

pulmonary circulation Generalized edema Portal edema—nutmeg liver

• Left side failure—volume backs up behind systemic circulation Pulmonary edema and pleural effusion

• Distension of alveolar capillaries leading to capillary rupture and red cells in alveoli

• Intra-alveolar macrophages phagocytose red cells and accumulate hemosiderin

• Fibrosis of the interstitium with hemosiderin deposition• Serous or serosanguinous effusions surrounding lungs

Congestive heart failure

• Reduced cardiac output

• Renal hypoperfusion

• Activation of renin-angiotensin-aldosterone axis Early response is beneficial

• sodium and water retention increased vascular toneelevated antidiuretic hormone (ADH) improved cardiac outputrestored renal perfusion

Ongoing response increases edema• Volume of blood exceeds volume of vasculature• Fluids build up in tissues

Anasarca

Hyperemia, injury

Trivial and life-threatening edema

Pitting edema

Elephantiasis--lymphedema

Peau d’orange and post-mastectomy lymphedema

Ascites due to portal congestion

Nutmeg liver

Hepatic congestion

Effusions• Extravascular fluid collections can be classified as

follows: Exudate: extravascular fluid collection that is rich in protein

and/or cells. Fluid appears grossly cloudy. Transudate: extravascular fluid collection that is basically an

ultrafiltrate of plasma with little protein and few or no cells. Fluid appears grossly clear.

• Effusions into body cavities can be further described as follows: Serous: a transudate with mainly edema fluid and few cells. Serosanguinous: an effusion with red blood cells. Fibrinous (serofibrinous): fibrin strands are derived from a

protein-rich exudate. Purulent: numerous PMN's are present. Also called "empyema"

in the pleural space.

Pleural effusions and edema

Fibrinous exudate

Pleural effusion

Pleural effusion

Pulmonary edema

Dilated lymphatic vessels