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Oedema
 

Oedema

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Intracellular & extracellular compartments , a concise and comprehensive look into oedema .. done by Abbas & Khalifa -

Intracellular & extracellular compartments , a concise and comprehensive look into oedema .. done by Abbas & Khalifa -

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  • A1-most of the body mass is converted to massA2- women have more fat – decrementing space of waterThe key is surface area
  • Another minor compartment is trascellular fluid for example pericardial, peritoneal, pleural and cerebrospinal fluids
  • -because the plasma and interstitial fluid are separated by highly permeable capillary membrane-yes partially truebecause they have the same ionic composition but because the capillary membrane is impermeable to plasma proteins – except for some proteins that leak , also because the lymphatic system drains these proteins from the interstitium.Their concentration in the interstitial fluid is very low (some plasma proteins leak to ISF)
  • Because the cell membrane is permeable to water but relatively permeable to smaller solutes such as Na and Cla.k.autrafiltration but mainly Starling forces
  • 80% of total ECF osmolarity is due to Na and Cl total osmolarity of the 3 compartments is 300mOsm/L but the plasma is more by 1 50% of total ICF osmolarity is due to K mOsm/L because of the osmotic pressure of plasma proteins Osmosis ; from low saline environment to a concentrated one
  • Isotonic fluid examples are 0.9% NaCl or 5% glucose solution Hypertonic examples less than 0.9% NaClHypotonic examples higher than 0.9% NaClTonicity ; impaired solutes
  • Hyponatremia: decreased Na concentration 2 types:1- hyponatremia-dehydration: primary loss of NaClresuls in decreased ECF volume2- hyponatremia-overhydration: excess water retention which dilute Na in ECF
  • Because the plasma proteins that leaked to the intersitium have no other way to be removed
  • Interstitial fluid pressure is about -3 mmHg
  • All tissues of the body are made up of cells and connective tissues that hold the cells together. This connective tissue around the cells and blood vessels is known as the interstitium. Most of the body's fluids that are found outside of the cells are normally stored in two spaces; the blood vessels (as the "liquid" or serum portion of your blood) and the interstitial spaces (not within the cells). In various diseases, excess fluid can accumulate in either one or both of these compartments.
  • Lean ; little fat part in meat
  • Extravascular fluid can also collect in body cavities such as the pleural cavity ( hydrothorax or pleural effusion ) , the pericardial cavity ( hydro pericardium ), the abdominal cavity ( hydroperitoneum or ascites) Anasarca is severe, generalized edema marked by profound swelling of subcutaneous tissues and accumulation of fluid in body cavities.
  • Cirrhosis is a chronic disease of the liver marked by degeneration of cells, inflammation, and fibrous thickening of tissue. It is typically a result of alcoholism or hepatitis.
  • Normally, the outflow of fluid produced by hydrostatic pressure at the arteriolar end of the microcirculation is neatly balanced by inflow due to the slightly elevated osmotic pressure at the venular end; hence there is only a small net outflow of fluid into the interstitial space, which is drained by lymphatic vessels. Either increased hydrostatic pressure or diminished colloid osmotic pressure causes increased movement of water into the interstitium (Fig. 3-2). This in turn increases the tissue hydrostatic pressure, and eventually a new equilibrium is achieved. Excess edema fluid is removed by lymphatic drainage and returned to the bloodstream by way of the thoracic duct (Fig. 3-2).
  • Factors influencing fluid movement across capillary walls. Capillary hydrostatic and osmotic forces are normally balanced so there is little net movement of fluid into the interstitium. However, increased hydrostatic pressure or diminished plasma osmotic pressure leads to extravascular fluid accumulation (edema). Tissue lymphatics drain much of the excess fluid back to the circulation by way of the thoracic duct; however, if the capacity for lymphatic drainage is exceeded, tissue edema results.
  • Transudate – edema fluid Exudate – Inflammatory edema fluid

Oedema Oedema Presentation Transcript

  • Intracellular, Extracellular Compartments, and Oedema A&M
  • Water Water is the major constitute of body fluids 60% of body weight or 42 L Daily water intake: 1- ingestion accounts for about 2100 ml/day 2- a result of oxidation of carbohydrates accounts for about 200 ml/day Daily water output: 1- insensible water loss: evaporation from respiratory tract and skin about 700 ml/day 2- sensible water loss: in sweat (about 100 ml/day), in feces ( about100 ml/day), and as urine (about 1.4 L/day)
  • There is balance between water intake (2500 ml/day) and output (2500 ml/day)
  • Category Water Men 60% women 50% Newborn babies 70-75% water percentage decreases as the person gets older (Why?) Women have low water percentage compared to men (Why?)
  • Body fluid compartments - Total body fluid is distributed into 2 compartments: 1- Intracellular compartment 2- Extracellular compartment: interstitial fluid and plasma 1- Intracellular compartment: represent about 28 L from total 42 L (40% of body weight) The fluid inside the cells
  • 2- Extracellular compartment: the fluid outside the cells. divided into: A- the Plasma : about ¼ , 3 L of ECF B- the interstitial fluid: about ¾ , 11 L of ECF Composition of ECF and ICF: ECF: the plasma and interstitial fluid have the same ionic composition (Why?) - ECF composition is maintained by the kidneys - Interstitial fluid composition= plasma composition (true or false and why?)
  • ICF: is separated by cell membrane from ECF - It contains small amounts of Na and Cl and almost no Ca - Contains large amounts of K and P but moderate amounts of Mg and S - Also contains large amounts of proteins (4 times as much as of the plasma)
  • Regulation of fluid distribution The distribution of ECF between the plasma and interstitial spaces is determined by the balance between the hydrostatic and colloid osmotic forces across the capillary membrane. The distribution of fluid between IC and EC fluids is determined by osmotic effect of smaller solutes across the cell membrane (Why?)
  • Principle of fluid exchange Since water is the major component of IC and EC compartments we will focus on its exchange: Osmosis : the net diffusion of water across a selectively permeable membrane from a region with high water concentration to a region with low water concentration. -The rate of water diffusion is the rate of osmosis Osmole: the total number of particles in a solution if it’s measured by Osmole/Kg of water called Osmolality and if measured in Osmole/L of solution called Osmolarity
  • Osmotic Equilibrium OE is maintained between IC and ECFs We can divide fluids according to tonicity into 3 classes: 1- isotonic: IC=EC and solutes can’t leave the cell it doesn’t cause the cell to shrink or swell 2- hypotonic: has lower concentration of impearment solutes. Water will diffuse into the cell causing its swelling 3- hypertonic: has higher concentration of impearment solutes. Water will diffuse out of the cell causing its shrinkage
  • Basic principles of exchange across the cell membrane 1- water moves across the cell membrane freely 2- the cell membrane is almost completely impermeable to solutes
  • Physiology: Edema Edema: presence of excessive fluid in the tissues Edema can be divided into: 1- IC edema: excessive fluid inside the cells occurs in 3 conditions: A- hypornatremia (what?). B- depression of the metabolic system of the tissue. C- lack of adequate nutrients to the cell 2- EC edema: occur because of 2 reasons: A- abnormal leakage of fluid B- failure of lymphatic system to return fluid
  • How IC edema occurs? Blood flow delivery of oxygen and nutrients If blood flow becomes to slow to maintain normal tissue metabolism depression of cell membrane ionic pump Na that leaked into the cell can’t be pumped out IC Na concentration osmosis of water into the cell
  • EC edema The most important clinical cause of EC edema is extensive capillary filtration What are the determinants of capillary filtration? 1- filtration coefficient 2- capillary hydrostatic pressure. 3- plasma colloid osmotic pressure
  • Major types of EC edema 1-Lymphedema: when lymphatic function is impaired because of blockage or loss of lymphatic vessels Why it causes edema? Blockage of lymphatic vessel is associated with infections of lymphatic nodes ( filaria nematodes) Lymphedema can occur with certain types of cancer or after surgery
  • 2- Edema caused by heart failure: -fails to pump blood from arteries to veins venous and capillary pressure capillary filtration - AP excretion of salts by the kidneys blood volume capillary hydrostatic pressure - Blood flow to the kidneys aldosterone secretion renin secretion angiotensin II Salts and water retention 3- Edema caused by left-sided heart failure: (How?)
  • 4- edema caused by the Kidneys: Less excretion of salts and water by the kidneys cause: ECF volume to increase some of it leak to interstitial fluid and the other remains in the blood leading: 1- increase of interstitial volume 2- hypertension because of increased blood volume Leading ultimately to generalized body edema. 5- edema caused by plasma proteins: Low plasma protein concentration is due to
  • 1- failure to produce plasma proteins by the liver 2- leakage of plasma proteins from the plasma Leading to decreased plasma colloid osmotic pressure and increased capillary filtration and consequently to edema
  • Categories of Edema 1- Pitting Edema: when interstitial fluid pressure rises to +ive range leading to free fluid accumulation. It pushes the brush pile of proteoglycans filament apart. The fluid is not in Gel sate. 2- Nonpitting Edema: when tissue cells are swelled not the intersitium or when the interstitium becomes clotted with fibrinogen so that it can’t move freely
  • Why normal people don’t have edema? Because of the safety factors: 1- low compliance of interstitial fluid when its pressure is –ive. (providing 3 mmHg) 2- the ability of lymph flow to increase 10 to 20fold. (providing 7 mmHg) 3- wash-down of interstitial fluid protein concentration. (providing 7 mmHg) As a result there is 17 mmHg safety factor against edema
  • Pathology: OEDEMA Edema is observable swelling from fluid accumulation in body tissues. Edema most commonly occurs in the feet and legs, where it is referred to as peripheral edema. The swelling is the result of the accumulation of excess fluid under the skin in the spaces within the tissue
  • Approx. 60% of lean body weight is water; Two thirds of which is intracellular Most of the remaining water is found in extracellular compartments in the form of interstitial fluid ; only 5% of the body’s water is in plasma .
  • Body Cavities
  • Pathophysiological causes Increased Hydrostatic pressure Impaired venous return Congestive heart failure Constrictive pericarditis Ascites (liver cirrhosis) Venous obstruction or compression Thrombosis External pressure (e.g., mass) Lower extremity inactivity with prolonged dependency
  • .. Arteriolar Dilation Heat Neurohumoral dysregulation
  • Reduced Plasma Osmotic Pressure (Hypoproteinemia) Protein-losing glomerulopathies (nephrotic syndrome) Liver cirrhosis (ascites) Malnutrition Protein-losing gastroenteropathy
  • Lymphatic Obstruction Inflammatory Neoplastic Postsurgical Post-irradiation
  • Sodium Retention Excessive salt intake with renal insufficiency Increased tubular reabsorption of sodium Renal hypoperfusion Increased renin-angiotensin-aldosterone secretion
  • Inflammation Acute inflammation Chronic inflammation Angiogenesis
  • Physiology Fluid movement between the vascular and interstitial spaces is governed mainly by two opposing forcesthe vascular hydrostatic pressure and the colloid osmotic pressure produced by plasma proteins.
  • Pathophysiology Incremented Hydrostatic Pressure Decremented Plasma Osmotic Pressure Increased Vascular Permeability Lymphatic Obstruction Sodium & Water Retention
  • MORPHOLOGY Edema is easily recognized on gross inspection; microscopic examination shows clearing and separation of the extracellular matrix elements. Although any tissue can be involved, edema most commonly is encountered in subcutaneous tissues, lungs, and brain.
  • The Lymphatic System Anatomy
  • Summary Edema is the result of the movement of fluid from the vasculature into the interstitial spaces; the fluid may be protein-poor (transudate) or proteinrich (exudate).
  • Summary Edema may be caused by: increased hydrostatic pressure (e.g., heart failure) increased vascular permeability (e.g., inflammation) decreased colloid osmotic pressure, due to reduced plasma albumin decreased synthesis (e.g., liver disease, protein malnutrition) increased loss (e.g., nephrotic syndrome) lymphatic obstruction (e.g., inflammation or neoplasia). sodium retention (e.g., renal failure)
  • REFRENCE 1-ROBBIN’S BASIC PATHOLOGY –CH3 2-GUYTON & HALL 12E –CH25 3-MEDICINENET