Cardinal Manifestation of Disease:

EDEMA

Dr. Meg-angela Christi Amores

Water in the body

• Total body water (TBW)– Compartments: 1. Intracellular Fluid - 75%2. Extracellular Fluid (ECF) – 25%

– Plasma 25%– Interstitial Fluid 75%

What is edema?

• clinically apparent increase in the interstitial fluid volume

• weight gain of several kilograms usually precedes overt manifestations of edema

Edema

• Anasarca - gross, generalized edema• Ascites and hydrothorax -accumulation of

excess fluid in the peritoneal and pleural cavities, respectively, and are considered to be special forms of edema

Pathogenesis• Starling Forces– regulate the disposition of fluid between these

two components of the extracellular compartment – hydrostatic pressure within the vascular system

and the colloid oncotic pressure in the interstitial fluid – promote movement out into interstitium

Starling Forces

• πi – Interstitial Oncotic pressure• πc – capillary oncotic pressure• Pi – interstitial hydrostatic pressure• Pc – capillary hydrostatic pressure

Starling Forces

• movement of water and diffusible solutes from the vascular space at the arteriolar end of the capillaries

• Fluid is returned from the interstitial space into the vascular system at the venous end and lymphatics

Pathogenesis

• Capillary Damage– damage to the capillary

endothelium, which increases its permeability and permits the transfer of protein into the interstitial compartment

– from drugs, viral or bacterial agents, and thermal or mechanical trauma

– hypersensitivity reaction and is characteristic of immune injury

– Usually Inflammatory edema

Pathogenesis

• Reduction of Effective Arterial Volume– by a reduction of cardiac output and/or systemic

vascular resistance– retention of salt and, therefore, of water, ultimately

leading to edema• Renal Factors and RAA System– renal retention of Na+ is central – Diminished renal blood flow = renin release– Renin = release angiotensin I = angiotensin II– Angiotensin II - enhancing salt and water reabsorption

Pathogenesis

• Others:– Argininine Vasopressin– Endothelin– Natriuretic peptides

Clinical Causes of Edema

• Obstruction of Venous Drainage of a limb• Congestive Heart Failure• Nephrotic Syndrome and Hypoalbuminemia• Cirrhosis• Drug-induced Edema• Idiopathic Edema

Obstruction of Venous Return

• hydrostatic pressure in the capillary bed upstream (proximal) to the obstruction increases

• Alternative route may also be blocked (lymph)• there is trapping of fluid in the extremity• displacement of fluid into a limb occur at the

expense of the blood volume in the remainder of the body = dec arterial blood volume - retention of NaCl and H2O

Congestive Heart Failure

• accumulation of blood in the venous circulation due to:1. impaired systolic emptying of the ventricle(s)2. impairment of ventricular relaxation

• Low cardiac output leads to:– a decrease in baroreflex-mediated inhibition of

the vasomotor center activates renal vasoconstrictor nerves and the RAA system, causing Na+ and H2O retention

Nephrotic Syndrome

• Proteinuria• Hypoalbuminemia• diminished colloid oncotic pressure due to losses

of large quantities of protein into the urine• NaCl and H2O that are retained cannot be

restrained within the vascular compartment• Impaired renal function contributes further to

the formation of edema

Nephrotic Syndrome

Cirrhosis

• hepatic venous outflow blockade• expands the blood volume and increases

hepatic lymph formation• as a potent stimulus for renal Na+ retention• activation of the RAA system, of renal

sympathetic nerves, and of other NaCl- and H2O-retaining mechanisms

Drug-Induced

• Nonsteroidal anti-inflammatory drugs• Antihypertensive agents• Direct arterial/arteriolar vasodilators• Calcium channel antagonists• A -Adrenergic antagonists• Steroid hormones• Cyclosporine• Growth hormone

What caused the edema?

• Ascites• jaundice, and spider angiomas• collateral venous channels• = CIRRHOSIS

What caused the edema?

• Gallop rhythm• Dyspnea• basilar rales• Venous distention• Hepatomegaly• Cardiomegaly• = HEART FAILURE

What caused the edema?

• Blood in urine• Proteinuria• Hypoalbuminemia• = NEPHROTIC SYNDROME

Distribution

• thrombophlebitis, chronic lymphangitis, resection of regional lymph nodes, filariasis

• =LOCALIZED

• Heart failure, nephrotic syndrome, cirrhosis• =GENERALIZED

• For the next meeting, read on Stroke Syndromes• Harrison’s Principles of Internal Medicine 17th

edition