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CHAPTER 4

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  1. CHAPTER4 • Hemodynamic Disorders • Thromboembolic Disease • Shock

  2. Overview • Edema • Hyperemia and Congestion • Hemorrhage • Hemostasis and Thrombosis • Embolism • Infarction • Shock

  3. Fluid Compartments Goldman: Cecil Textbook of Medicine, 22nd ed

  4. Body Fluid Compartments

  5. Walter B Cannon • Fight or flight response • Concept of homeostasis • maintenance of internal environment or milieu • usually involves negative feedback loops • Mechanisms of homeostatis • physiologic circumstances • have evolved over thousands of years • adaptations usually beneficial-“Wisdom of the Body” • pathologic conditions • sick individuals do not survive in nature • adaptations may be harmful- “ folly of the body ”

  6. Edema • Definition • abnormally increased interstitial fluid • Location • Peripheral • Cerebral • Pulmonary • Special Types • hydrothroax (pleural effusion) • hydroperitoneum (ascites) • Anasarca

  7. Starling Forces Affecting Fluid Movement Downloaded from: Robbins & Cotran Pathologic Basis of Disease (on 27 June 2005 07:26 PM) © 2005 Elsevier

  8. Starling Forces

  9. Starling Law Of Capillary-interstitial Liquid Exchange Liquid Accumulation = K[(PC – PIF) - δ (πPL - πIF)] - Q lymph K, hydraulic conductance (directly proportional to membrane surface area and inversely proportional to membrane thickness) PC, mean intracapillary pressure PIF, mean interstitial liquid pressure δ , reflection coefficient of macromolecules π IF, oncotic pressure of interstitial liquid π PL, oncotic pressure of the plasma Q lymph, lymphatic flow

  10. Pathophysiologic Categories of Edema • Increased Hydrostatic Pressure • Reduced Plasma Osmotic Pressure (Hypoproteinemia) • Lymphatic Obstruction • Sodium Retention • Inflammation

  11. 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

  12. Reduced Plasma Osmotic Pressure (Hypoproteinemia) • Protein-losing glomerulopathies (nephrotic syndrome) • Liver cirrhosis (ascites) • Malnutrition • Protein-losing gastroenteropathy

  13. Lymphatic Obstruction • Inflammatory • Neoplastic • Postsurgical • Postirradiation

  14. Sodium Retention • Excessive salt intake with renal insufficiency • Increased tubular reabsorption of sodium • Renal hypoperfusion • Increased renin-angiotensin-aldosterone secretion

  15. Downloaded from: Robbins & Cotran Pathologic Basis of Disease (on 27 June 2005 07:26 PM) © 2005 Elsevier

  16. Volume Repletion Reaction Goldman: Cecil Textbook of Medicine, 22nd ed.

  17. Localization of Edema • Generalized • hypoproteinemia: delicate tissues-periorbital, face • accentuated in dependent areas • Localized • Cerebral • abscess, neoplasm-localized • head trauma, anoxia, encephalitis-generalized • Pulmonary • left heart failure • infection and toxins • One leg • thrombophlebitis

  18. Hyperemia and Congestion both involve increased blood volume • Hyperemia – active process • functional • Inflamatory • Congestion – passive process • acute • chronic – secondary changes • fibrosis • hemosiderin laden macrophages

  19. Pitting Edema

  20. Ascites

  21. Kerley B Air Bronch-ogram

  22. Transudate vs Exudate • Transudate • results from disturbance of Starling forces • specific gravity < 1.012 • protein content < 3 g/dl • Exudate • results from damage to the capillary wall • specific gravity > 1.012 • protein content > 3 g/dl

  23. Leading Causes of Pleural Effusion in the United States, According to Analysis of Patients Subjected to Thoracentesis Light, R. W. N Engl J Med 2002;346:1971-1977

  24. Sensitivity of Tests to Distinguish Exudative from Transudative Effusions Light, R. W. N Engl J Med 2002;346:1971-1977

  25. Transtentorial Herniation Of The Temporal Lobe With Compression Of The Brain Stem Carter, B. S. et al. N Engl J Med 2004;350:707-716

  26. Normal Downloaded from: Robbins & Cotran Pathologic Basis of Disease (on 27 June 2005 07:26 PM) © 2005 Elsevier

  27. Hyperemia Downloaded from: Robbins & Cotran Pathologic Basis of Disease (on 27 June 2005 07:26 PM) © 2005 Elsevier

  28. Downloaded from: Robbins & Cotran Pathologic Basis of Disease (on 27 June 2005 07:26 PM) © 2005 Elsevier

  29. Hemorrhage • Site • external • hematoma • Size • petechiae: 1-2 mm, non-palpable • purpura: ≥ 3mm • ecchymoses > 1 cm • Within body cavities • hemothroax • hemopericardium • hemoperitoneum

  30. Petechiae

  31. Purpura

  32. Ecchymosis

  33. Phases of Hemostasis • Vasoconstriction • Primary Hemostasis • formation of platelet plug • Secondary Hemostasis • clot formation • Thrombus and Antithrombotic Events • regulation of thrombus formation and dissolution

  34. Effects of Hemorrhage • Site of hemorrhage • brain, pericardium, pleural space • internal: iron can be reutilized • external: may lead to iron deficiency • Rate of blood loss • acute • loss of > 20% of blood volume may cause hypotension or hypovolemic shock • hemoglobin concentration not altered • non-acute • volume loss compensated by shift of fluid from extravascular to intravascular compartment • hemoglobin concentration decreased

  35. Hematocrit

  36. Vasoconstriction • Endothelin release • Reflex neurogenic • Thrombaxane A2 (released with 1° hemostasis)

  37. Downloaded from: Robbins & Cotran Pathologic Basis of Disease (on 27 June 2005 07:26 PM) © 2005 Elsevier

  38. Primary Hemostasis • Platelet Adhesion • Platelet Release • Platelet Aggregation • Formation of platelet plug

  39. Platelet Adhesion • exposed collagen • platelet surface receptors (GpIb) • von Willebrand factor

  40. Platelet adhesion and aggregation Downloaded from: Robbins & Cotran Pathologic Basis of Disease (on 27 June 2005 07:26 PM) © 2005 Elsevier

  41. Platelet Granules • Alpha Granules • P-selectin • fibrinogen and other clotting factors • platelet derived growth factor • Dense Granules • ADP and ATP • histamine • serotonin • epinephrine

  42. Platelet Release • Thrombaxane A2 • ADP (adenosine diphosphate) • vWF and other clotting factors • Platelet derived growth factor

  43. Platelet Release