Gangrene PDF

- Definition, causes, pathogenesis and different types of gangrene. - Definition, causes, pathogenesis and types of edema. Definition: massive tissue necrosis followed by putrefaction Breakdown of proteins of necrotic tissue by sapro...

- Definition, causes, pathogenesis and different types of gangrene. - Definition, causes, pathogenesis and types of edema. Definition: massive tissue necrosis followed by putrefaction Breakdown of proteins of necrotic tissue by saprophytic organism Hydrogen sulphide + Hydrogen iron of Hb sulphide = Iron sulphide Bad odor Black colouration Causes: ischemia or toxins lead to tissue necrosis Sites: All tissues in the affected organ are involved in the gangrene Types: 1-Dry Tissue Fluid 2-Moist (Wet) 3- Infective gangrene 4- Gas gangrene Pathogenesis: Occlusion of arterial blood supply of an organ WITH : - patent veins - poor collaterals Pathogenesis: Occlusion of arterial blood supply of due to: 1-Thrombosis (atherosclerosis) 2- Embolism 3- Surgical Ligature. 4- Ergot poisoning : arterial spasm EX. -The commonest example is senile gangrene of the lower limb (exposed organs) -Steps : 1-There is gradual obstruction of arteries, so gangrene spread slowly. 2- At first, the affected part is pale, numb, cold & painful 3-When necrosis start, it becomes red due to hemolysis of RBCs & diffusion of blood pigment Red color -associated with loss of sensation (necrosis of nerves) Steps: 4-Then saprophytic bacteria start putrefaction of the necrotic part Black colouration Bad odour Tissue fluid are drained via opened lymphatics & veins Dry gangrene (shrunken and mummified) Exposed Surface organs evaporation 5- The gangrenous part irritates the living one and initiates inflammation endothelial cell injury propagation of thrombus spread of gangrene from big toe to foot & leg. 6-The gangrene spread slowly until it reaches area of good collateral circulation. the gangrene stops 7-At the site of gangrene stoppage an inflammatory zone appear between healthy & gangrenous part called line of demarcation 8-Then granulation tissue formation & (rich in phagocytes) developed at the healthy part separation of the gangrenous part at the line of separation conical stump  Gangrene It affects speeds internal Moist Saprophytic rapidly Sudden gangrene bacteria organs -No line arterial & (More begin to where invade and demarcation venous fluids in evaporation grow -No line of occlusion the is not rapidly. separation allowed tissues) -Toxemia EX. 1--Internal organs as intestines in strangulated hernia 2-It may affect limbs when both artery and vein are occluded as in : -Crush injuries -Diabetic gangrene Steps: -At first, venous obstruction occur edema (accumulation of fluid) & congestion of intestinal loops -Then arterial occlusion occur necrosis followed by invasion via saprophytic bacteria starting putrefaction of the necrotic part black coloration bad odour  Difference between dry & wet gangrene Dry Gangrene Moist gangrene 1- arterial occlusion (Gradual) 1-arterial & venous occlusion (Sudden ) 2-Exposed parts (limbs) 2-Internal organs (intestine) 3-Tissue mummification 3-Tissue oedema 4-Slow spread 4-Rapid spread 5-Slow putrefaction 5-Rapid putrefaction 6-Mild toxemia 6-Sever toxemia 7-Marked line of demarcation 7-Poor line of demarcation 8-Self separation my occur 8-Self separation absent -Definition: A subtype of moist gangrene at which bacteria cause both tissue necrosis and putrefaction. Lung gangrene -Pathogenesis: 1-Pathogenic bacteria produce toxins cause tissue necrosis. 3-Next saprophytic bacteria act on the dead protein causing putrefaction. Types: Bed sores (1 ) Lung gangrene (2 )Bed sores (4 )Cancrum oris Cancrum oris (3 )Gas gangrene -Gas gangrene is a moist infective gangrene Pathogenesis: Infection by anaerobic bacteria - (Clostridium) -It affects muscle present in deep wounds contaminated by soil (fecal material) containing anaerobic bacteria (Clostridium) -Excessive production of different gases as hydrogen sulphide, hydrogen & carbon dioxide Definitions: is an abnormal accumulation of fluid in interstitial tissue & serous membranes. Causes (Proteins) -Localized: venous obstruction -Decrease -Generalized: in cases of protein intake right sided heart failure - Liver diseases -Salt and water retention - Proteinuria : by aldosterone in right sided heart failure Causes  Causes 4- Lymphatic obstruction: - Congenital lymphatic hypoplasia. - Inflammatory : specific (filariasis) or non specific lymphadenitis and lymphangitis - Fibrosis : post inflammatory or post irradiation - Tumor emboli - Compression from outside : tumors - Surgical removal of lymphatics as in cases of mastectomy (Excision of breast) as a treatment for breast cancer Types According to According to distribution of nature of fluid fluid Water Water only +proteins Soft Hard Generalized localized pitting Non pitting 1-Inflammatory 1-Cardiac 2- Venous 2- Renal obstruction 3- Nutritional 3- Lymphatic obstruction Renal Cardiac Nutritional In right sided Decreased Due to heart failure due protein proteinuria to: intake 1- Increased capillary hydrostatic pressure 2-Na and water retention : by aldosterone 3-Increased capillary permeability due to hypoxia  Obstructive Obstructive Inflammatory (venous) (lymphatic) causes of is caused by increased Thrombosis lymphatic capillary permeability or embolism obstruction 2-Compression from outside by gravid uterus liver fibrosis causes ascites Enumerate types of gangrene? Enumerate types of edema?