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 H 2 O

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 H 2 O retention

Nephrotic Syndrome Proteinuria Hypoalbuminemia diminished colloid oncotic pressure due to losses of large quantities of protein into the urine NaCl and H 2 O 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 H 2 O-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 17 th edition