Lecture 3 Hemodynamic Disorders: Edema and Hemorrhage PDF

Lecture 3 Hemodynamic Disorders: Edema ; Hemorrhage Year/Level: D2 / Semester 2 Dr Mohammad Shahid Iqbal M.D Assistant Professor of Pathology 1 Edema and Effusion Edema Pleural effusion 2 Edema and Effusio...

Lecture 3 Hemodynamic Disorders: Edema ; Hemorrhage Year/Level: D2 / Semester 2 Dr Mohammad Shahid Iqbal M.D Assistant Professor of Pathology 1 Edema and Effusion Edema Pleural effusion 2 Edema and Effusion Definition: Edema: Accumulation of fluid in tissues Effusion: Accumulation of fluid in body cavities Swelling due to the expansion of interstitial fluid volume in tissues or an organ Seen due to disorders that disturb cardiovascular, renal, or hepatic function Critical clinical feature for diagnostic medicine Edema presentation: Unilateral, bilateral, localized, or generalized 3 Normal Tendency of vascular Tendency of plasma hydrostatic BALANCE colloid osmotic pressure to push water and pressure to pull A small net water and salts back salts out of capillaries into movement of fluid into the into vessels interstitial space the interstitium. Drains into lymphatic vessels; Ultimately returns to the bloodstream NO EDEMA 4 Factors influencing fluid movement across capillary walls 5 Edema and Effusion Elevated hydrostatic pressure or diminished colloid osmotic pressure disrupts this balance and results in increased movement of fluid out of vessels. Fluid accumulates: If net rate of fluid movement exceeds the rate of lymphatic drainage If Serosal surface involved: Fluid may accumulate within the adjacent body cavity as an effusion. 6 Edema and Effusion Edema fluids and effusions may be inflammatory or noninflammatory Inflammation-related edema and effusions are - Protein-rich exudates - Accumulate due to increases in vascular permeability caused by inflammatory mediators. Non-inflammatory edema and effusions: Protein-poor fluids called transudates. 7 Causes of Edema Increases in hydrostatic pressure: Mainly caused by disorders that impair venous return Reduced Plasma Osmotic Pressure: Due to inadequate albumin synthesis or increased loss Increased salt retention—with obligate retention of associated water Causes both increased hydrostatic pressure Diminished vascular colloid osmotic pressure (due to dilution) Disruption of lymphatic vessels: Impaired clearance of interstitial fluid Lymphedema in Filariasis (Due to obstructive fibrosis of lymphatics and lymph nodes) Tissue factor: Oncotic pressure of interstitium Hydrostatic pressure 8 Pathophysiology of Edema 9  Pathophysiologic categories of Edema 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 Malnutrition Protein-losing gastroenteropathy 10 Pathophysiologic categories of Edema Lymphatic Obstruction Inflammatory Neoplastic Postsurgical Postirradiation Sodium Retention Excessive salt intake with renal insufficiency Increased tubular reabsorption of sodium Renal hypoperfusion Increased renin-angiotensin-aldosterone secretion Inflammation: Acute, Chronic, Angiogenesis 11 Mechanism of Edema Mechanisms of systemic edema in heart failure, renal failure, malnutrition, hepatic failure, and nephrotic syndrome. 12  Morphology of Edema Most common sites: Subcutaneous tissue, lungs and brain Grossly: Edema recognized easily Microscopically: Clearing and separation of the extracellular matrix (ECM) and cell swelling. Subcutaneous edema: Diffuse in regions with high hydrostatic pressures Distribution is often influenced by gravity: -Legs when standing and the sacrum when recumbent (Dependent edema) Pitting Edema: Finger pressure over markedly edematous subcutaneous tissue displaces the interstitial fluid and leaves a depression Edema in severe renal diseases: Appears in loose connective tissue: Periorbital edema 13  Morphology of Edema Pitting Edema Filariasis (Elephantiasis) Bilateral Pedal edema (Subcutaneous edema) Periorbital Edema in Nephrotic syndrome 14  Pulmonary Edema Acute pulmonary oedema is the most important form of local oedema as it causes serious functional impairment. The fluid accumulation is not only in the tissue space but also in the pulmonary alveoli Etiology and Pathogenesis Elevation in pulmonary hydrostatic pressure due to Left heart failure, mitral stenosis, pulmonary vein obstruction, thyrotoxicosis, cardiac surgery, nephrotic syndrome and obstruction to the lymphatic outflow by tumour or inflammation. Increased vascular permeability High altitude 15 Pulmonary Edema 16  Morphology of pulmonary edema Pulmonary edema: Lungs are often two to three times their normal weight Section shows frothy, blood-tinged fluid—a mixture of air, edema, and extravasated red cells. Alveoli filled with a smooth to slightly floccular pink material(Red arrow). Capillaries in the alveolar walls are congested (blue arrow) with many red blood cells. 17  Morphology of Cerebral edema Brain edema Localized or generalized Depends on the nature and extent of the pathologic process or injury. Localized- Due to: Abscess or neoplasm Generalised- Encephalitis, hypertension, obstruction to venous outflow Generalized edema: Flat gyri, narrowed sulci, compressed ventricular cavities Brain is swollen 18  Effusions Transudative effusions are typically protein-poor translucent, and straw colored Effusions involving the pleural cavity: Hydrothorax Pericardial cavity :Hydropericardium Peritoneal cavity: Hydroperitoneum or Ascites Peritoneal effusions due to lymphatic blockage: chylous effusion: Milky due to the presence of lipids absorbed from the gut Exudative effusions: Protein-rich and often cloudy (presence of white) cells. Ascites Anasarca: Severe and generalized edema which includes marked swelling of the subcutaneous tissues 19  Hemorrhage Hemorrhage simply means bleeding Can range from a “nick,” to a severely spurting artery, to a ruptured spleen -External bleeding (visible hemorrhage) -Internal bleeding 20  Hemorrhage ‘Simply means bleeding’ Haemorrhage is the escape of blood from a blood vessel. May occur externally, or internally into the serous cavities Eg. Haemothorax, Haemoperitoneum, Haemopericardium, or into a hollow viscus. Extravasation of blood into the tissues with resultant swelling is known as haematoma. Large extravasations of blood into the skin and mucous membranes are called ecchymoses. Purpuras are small areas of haemorrhages (upto 1 cm) into the skin and mucous membrane Petechiae are minute pinhead-sized haemorrhages. 21 Hemorrhage Ecchymosis Hematoma 22  Hemorrhage Acute hemorrhage: The blood loss may be large and sudden Chronic: small repeated bleeds may occur over a period of time Causes of haemorrhage Trauma to the vessel wall e.g. penetrating wound in the heart or great vessels, during labour etc. Spontaneous haemorrhage e.g. rupture of an aneurysm, septicaemia, bleeding diathesis (such as purpura), acute leukaemias, pernicious anaemia, scurvy. 23  Hemorrhage Inflammatory lesions of the vessel wall e.g. bleeding from chronic peptic ulcer, typhoid ulcers, blood vessels traversing a tuberculous cavity in the lung, syphilitic involvement of the aorta, polyarteritis nodosa. Neoplastic invasion e.g. haemorrhage following vascular invasion in carcinoma of the tongue. Vascular diseases e.g. Atherosclerosis. Elevated pressure within the vessels e.g. cerebral and retinal haemorrhage in systemic hypertension, severe haemorrhage from varicose veins due to high pressure in the veins of legs or oesophagus. 24  Hemorrhage: Effects The effects of blood loss depend upon 3 main factors: i) The amount of blood loss ii) The speed of blood loss iii) The site of haemorrhage 25  Hemorrhage: Effects The loss up to 20% of blood volume suddenly or slowly generally, has little clinical effects because of compensatory mechanisms. A sudden loss of 33% of blood volume may cause death, while loss of up to 50% of blood volume gradually over a period of 24 hours may not be necessarily fatal. However, chronic blood loss generally produces iron deficiency anaemia, whereas acute haemorrhage may lead to serious immediate consequences such as hypovolaemic shock. 26  References 1. Robbins and Cotran Pathologic Basis of Disease; 10th ed. 2021 2. HarshMohan Textbook of Pathology. 7th edition. 27  Thank You Any questions? [email protected] 28