Lecture 2: Edema (PDF)

Lower Extremity Edema Disorders of Circulatory System 1.Edema By Prof. Manal El-Hamamsy Clinical Pharmacy Department Faculty of Pharmacy Ain Shams Unive...

Lower Extremity Edema Disorders of Circulatory System 1.Edema By Prof. Manal El-Hamamsy Clinical Pharmacy Department Faculty of Pharmacy Ain Shams University  Tissue Fluid small vein small artery cells venule arteriole lymphatic tissue fluid capillaries 30 l of plasma pass out of capillaries/ day into the Interstitial Fluid. 27 l resorbed by capillary 3 l left in tissue spaces get resorbed by lymphatics.  Interstitial Fluid http://www.biosbcc.net/doohan/sample/images/CO%20and%20MAP/0313filtration.jpg ▪ Fluid between cells ▪ Derived from capillaries ▪ Solutes like plasma except for protein content ▪ Movement of Fluid Across Capillaries  ‫بسم هللا الرحمن الرحيم‬ ‫اء‬ ‫س َم ِّ‬‫الريَا َح لَ َواقِّ َح فَأ َ ْن َز ْلنَا ِّم َن ال َّ‬ ‫س ْلنَا ِّ‬ ‫ { َوأ َ ْر َ‬ ‫ين}‬‫سقَ ْينَا ُك ُموهُ َو َما أ َ ْنت ُ ْم لَهُ ِّب ََ ِّازنِّ َ‬ ‫َما ًء فَأ َ ْ‬ ‫[سورة الحجر ‪]22‬‬ ‫في اآلية إعجازا يشير إلى أن الجسم ال يَزن الماء بعد‬ ‫شربه؛ ويتَلص منه مباشرة دفعا لضرر تَزينه‪ ،‬وأن هذا‬ ‫ين”‬ ‫مدلول قوله تعالى‪َ “ :‬و َم ۤا أَنت ُ ۡم لَهُۥ ِّب ََ ٰـ ِّزنِّ َ‬ Edema Definition Oedema is an abnormal presence of excessive fluid in the interstitial space. The fluid is predominantly water, but protein and cell-rich fluid can accumulate if there is infection or lymphatic obstruction. PATHOPHYSIOLOGY  Oedema ….Pathophysiology ▪ Edema results from increased movement of fluid from the intravascular to the interstitial space or decreased movement of water from the interstitium into the capillaries or lymphatic vessels. ▪ The mechanism involves one or more of the following: Increased capillary hydrostatic pressure Decreased plasma oncotic pressure Increased capillary permeability Obstruction of the lymphatic system  Oedema …. Pathophysiology ▪ The movement of water and low molecular weight solutes http://www.biosbcc.net/doohan/sample/images/CO%20and%20MAP/0313filtration.jpg such as salts between the intravascular and interstitial spaces is controlled primarily by the opposing effect of vascular hydrostatic pressure and plasma colloid osmotic pressure. ▪ Normally the outflow of fluid from the arteriolar end of the microcirculation into the interstitium is nearly balanced by inflow at the venular end. ▪ A small residual amount of fluid may be left in the interstitium and is drained by the lymphatic vessels, ultimately returning to the bloodstream via the thoracic duct. http://3.bp.blogspot.com/-z0FP14m9pw4/UHr2HgoBHqI/AAAAAAAAAbM/cOOBh7nu7go/s400/edema.jpg  Oedema …. Pathophysiology ▪ Either increased capillary pressure, diminished colloid osmotic pressure or inadequate lymphatic drainage can result in an abnormally increased interstitial fluid i.e., edema. ▪ An abnormal increase in interstitial fluid within tissues is called edema, while fluid collections in the different body cavities are variously designated hydrothorax (pleural cavity), hydropericardium (pericardial cavity) and hydroperitoneum (the last is more commonly called ascites). ▪ Anasarca is a severe and generalized edema with widespread subcutaneous tissue swelling.  Oedema …. Pathophysiology ▪ The diagram above shows the actual change in pressure gradients at the capillary level. http://4.bp.blogspot.com/-8wR1MUvgys4/UHr2IrW_95I/AAAAAAAAAbU/hMmm6N0G5sY/s1600/edema1.jpg ▪ The numbers represent the pressure in the vessels in mmHg. ▪ At the arteriolar end, the hydrostatic pressure (outward force) is 37 mmHg while the oncotic pressure and interstitial pressure (inward forces) are 25 and 1 mmHg respectively. ▪ Thus, the net outward force is 37 – (25+1) = +11 mmHg. ▪ Since the net outward force is positive fluid moves from the capillary to the interstitial spaces.  Oedema …. Pathophysiology ▪ At the venular end, the hydrostatic pressure is http://4.bp.blogspot.com/-8wR1MUvgys4/UHr2IrW_95I/AAAAAAAAAbU/hMmm6N0G5sY/s1600/edema1.jpg lower and has a value of 17 mmHg. ▪ The oncotic and interstitial pressure on the other hand remain the same i.e., a total of 26 mmHg (25+1). ▪ Thus, the net outward force is 17 – (25+1) = -9 mmHg. ▪ Since the outward force is negative, it means fluid is not getting out of the capillary but instead it is moving into it.  Oedema …. CLASSIFICATION 1. According to location: a) Localized b) Generalized 2. According to pathophysiological mechanism: a) Transudate (low protein content) b) Exudate (high protein content) 3. According to clinical finding: a) Pitting b) Non-pitting. Oedema …. CLASSIFICATION According to location 1.LOCALIZED EDEMA ▪It means that the edema is localized to a specific region of the body. ▪It is commonly due to venous/lymphatic causes, allergy and inflammation.  1.LOCALIZED EDEMA I. Venous edema ▪ It is due to high venous pressure or venous constriction. ▪ Intravascular venous obstruction e.g.,: Deep vein thrombosis (DVT) or an external compression like a mass (tumour) are the common causes but there can also be failure of venous pumps due to paralysis of muscles (Cerebro-vascular accident), immobilization of parts of the body (fractures) and failure of venous valves (Varicose veins). ▪ It is more frequent to see localized edema in the lower limbs, but the upper limbs may also be affected.  1.LOCALIZED EDEMA II. Lymphatic edema ▪ It is due to a blockage in the lymphatic return. ▪ It commonly occurs in conditions like cancer/ post-radiation, infections like elephantiasis (Filaria nematodes), surgery or congenital absence or abnormality of lymphatic vessels. ▪ The edema is persistent and non-pitting type. ▪ In case of elephantiasis, the affected limb may be dramatically enlarged.  https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRJ6aUG3U5K5X-nCJqXiGpSDNpkjcRueEGfHz6-sQa4Lam-mRHePw 1.LOCALIZED EDEMA III. Allergy/Angioedema (Quincke edema) ▪ During a case of allergy there is release of histamine and other mediators that lead to vasodilation. ▪ The swelling can involve the face, lips, tongue and even glottis. ▪ Edema of the glottis is a medical emergency as it can lead to asphyxia if not treated quickly. ▪ This type of edema is usually itchy but transitory. ▪ It resolves with antihistaminics and steroids. 1.LOCALIZED EDEMA VI. Inflammation ▪Here also there is vasodilation because of the inflammatory mediators. ▪Edema is seen with superficial (cellulitis) or deep infections (abscess).  2. GENERALIZED EDEMA ▪In this case the edema involves more than 1 part of the body simultaneously. ▪It is commonly due to cardiac, hepatic, renal or endocrine causes.  2.GENERALIZED EDEMA I. Cardiac edema ▪ The initial pathology is because of increased venous pressure but as the condition becomes more severe, there is impairment of renal blood supply, activation of rennin-angiotensin- aldosterone system and finally hypoalbuminemia secondary to liver stasis. ▪ Left sided heart failure leads to pulmonary edema while right sided heart failure causes peripheral edema, ascites, hydrothorax and anasarca in severe and long-standing cases. ▪ The edema is progressive. 2.GENERALIZED EDEMA I. Cardiac edema ▪The edema is usually of pitting type. ▪In early stages of heart failure, there is improved renal circulation at night leading to nycturia. ▪Thus, the edema will be less in the morning and progressively increases towards the end of the day.  2.GENERALIZED EDEMA III. Hepatic edema ▪ Liver pathology like cirrhosis leads to decreased synthesis of proteins. ▪ The hypoalbuminemia leads to decreased oncotic pressure. ▪ The scarred liver also causes a back pressure in the portal vein territory (portal vein hypertension) and increases the hydrostatic pressure there. ▪ These 2 factors combined lead to edema in the peritoneal cavity (ascites) and this in turn compresses the inferior vena cava and leads to edema in the lower limbs.  2.GENERALIZED EDEMA III. Renal edema ▪ Kidney diseases like nephritic syndrome with decreased glomerular filtration rate and sodium/water retention or nephrotic syndrome where there is albumin loss in the urine lead to generalized edema. ▪ The edema frequently occurs in lax connective tissue like the face, periorbital area and genitalia. ▪ It is of pitting type. ▪ It occurs mostly during the morning and is associated with vasoconstriction. ▪ Thus, it is called as ‘white’ edema.  2.GENERALIZED EDEMA VI. Endocrine edema ▪ Many endocrine problems can cause edema. ▪ In case of hyperaldosteronism (primary or secondary), there is retention of sodium and water. ▪ This leads to an increase in hydrostatic pressure. ▪ The edema is of pitting type. ▪ On the other hand, myxedema refers to a non-pitting type of edema seen in hypothyroidism. ▪ Finally, females experience edema as part of the premenstrual syndrome due to hormonal changes.  Oedema …. CLASSIFICATION ACCORDING TO PATHOPHYSIOLOGY I. Increased capillary pressure (increased hydrostatic pressure) ▪ Excessive kidney retention of salt and water Acute or chronic kidney failure Mineralocorticoid excess II. High venous pressure and venous constriction Impaired heart functioning (Congestive heart failure, constrictive pericarditis) Venous obstruction (Deep vein thrombosis, External compression like a mass or plaster) Failure of venous pumps (a) Paralysis of muscles (Cerebro-vascular accident) (b) Immobilization of parts of the body (Post-op, fractures) (c) Failure of venous valves (Varicose veins) Oedema …. CLASSIFICATION ACCORDING TO PATHOPHYSIOLOGY ▪ Decreased arteriolar resistance Excessive body heat Insufficiency of sympathetic nervous system Drugs (vasodilators, calcium channel blockers) ▪ Decreased plasma proteins Loss of proteins in urine (Nephrotic syndrome) or G.I.T (Protein-losing gastroenteropathy) Loss of protein from denuded skin areas Burns Wounds Failure to produce proteins Liver disease (Cirrhosis) Serious protein or caloric malnutrition Oedema …. CLASSIFICATION ACCORDING TO PATHOPHYSIOLOGY ▪ Increased capillary permeability Immune reactions that cause release of histamine and other immune products (Allergy) Toxins Bacterial infections (Cellulitis) Vitamin deficiency, especially vitamin C Prolonged ischemia Burns Oedema …. CLASSIFICATION ACCORDING TO PATHOPHYSIOLOGY ▪Blockage of lymph return Cancer Infections (Filaria nematodes) Surgery Congenital absence or abnormality of lymphatic vessels Post-radiation.  CLINICAL FEATURES ▪ In dependent edema, which is typically present in congestive heart failure and in conditions associated with a low plasma protein level, the swelling first appears at the ankles and over the dorsum of the foot and only gradually involves the legs, thighs and trunk. ▪ The best place to check for slight degrees of edema in an ambulant patient is behind the malleoli at the ankles. ▪ In bed-bound patients, edema often appears first over the sacrum.  CLINICAL FEATURES…cont., ▪ To recognize pitting edema, it is important to press firmly and for a sustained period of 20-30s over a bony prominence (tibia, lateral malleoli or sacrum) to provide effective compression. ▪ The 'pit' will be as easily felt as seen. ▪ If the finger pressure is not maintained for an adequate period of time, then slight degrees of edema may be overlooked. Edema  CLINICAL FEATURES…cont., ▪ Edema can be recognized by the pallid and glossy appearance of the skin over the swollen part, by its doughy feel and by the fact that it pits on finger pressure. ▪ The edema of lymphatic obstruction does not pit on pressure or there may be minimal pitting. ▪ The skin is usually thickened and tough. Pitting Edema Scale Grade Definition 1+ 2mm or less disappears immediately 2+ 2-4 mm few second rebound 3+ 4-6 mm 10-12 second rebound 4+ 6-8 mm > 20 second rebound Key Points Edema may result from a generalized or local process. Main causes of generalized edema are chronic heart, liver, and kidney disorders. Sudden onset should trigger prompt evaluation. Edema may occur anywhere in the body, including the brain. Not all edema is harmful; consequences depend mainly on the cause.