Hemodynamic Disorders in detail with there mechanisms

These slides give brief description about hemodynamic disorders.

1. Hemodynamic Disorders

2. contents Edema Pathophysiological causes of edema Morphology and clinical correlation of edema Hemorrhage Manifestations and clinical significance of hemorrhage

3. Edema E dema is an accumulation of interstitial fluid within tissues. Extravascular fluid can also collect in body cavities such as the pleural cavity (hydrothorax) , the pericardial cavity ( hydropericardium ) , or the peritoneal cavity ( hydroperitoneum , or ascites).

4. Anasarca is severe, generalized edema marked by profound swelling of subcutaneous tissues and accumulation of fluid in body cavities. Fluid movement abetween the vascular and interstitial spaces is governed mainly by two opposing forces—the vascular hydrostatic pressure and the colloid osmotic pressure produced by plasma proteins.

5. 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.

6. Either increased hydrostatic pressure or diminished colloid osmotic pressure causes increased movement of water into the interstitium . The edema fluid that accumulates owing to increased hydrostatic pressure or reduced intravascular colloid typically is a protein-poor transudate ; it has a specific gravity less than 1.012.

7. By contrast, because of increased vascular permeability, inflammatory edema fluid is a protein-rich exudate with a specific gravity usually greater than 1.020.

8. Pathophysiological Causes 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

9. Reduced Plasma Osmotic Pressure ( Hypoproteinemia ) Protein-losing glomerulopathies ( nephrotic syndrome) Liver cirrhosis (ascites) Malnutrition Protein-losing gastroenteropathy Lymphatic Obstruction Inflammatory Neoplastic Postsurgical Postirradiation

10. 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

11. Morphology Edema is easily recognized on gross inspection; microscopic examination shows clearing and separation of the extracellular matrix elements. Subcutaneous edema can be diffuse but usually accumulates preferentially in parts of the body positioned the greatest distance below the heart where hydrostatic pressures are highest.

12. Thus, edema typically is most pronounced in the legs with standing, a relationship termed dependent edema. Finger pressure over edematous subcutaneous tissue displaces the interstitial fluid, leaving a finger-shaped depression; this appearance is called pitting edema.

13. Edema due to renal dysfunction or nephrotic syndrome often manifests first in loose connective tissues (e.g., the eyelids, causing periorbital edema). With pulmonary edema, the lungs often are two to three times their normal waeight , and sectioning reveals frothy, sometimes blood-tinged fluid consisting of a mixture of air, edema fluid, and extravasated red cells.

14. Brain edema can be localized (e.g., due to abscess or tumor) or generalized, depending on the nature and extent of the pathologic process or injury.

15. Clinical Correlation Subcutaneous edema , signals potential underlying cardiac or renal disease; however, when significant, it also can impair wound healing or the clearance of infections. Pulmonary edema , frequently is seen in the setting of left ventricular failure but also may occur in renal failure, acute respiratory distress syndrome, and inflammatory and infectious disorders of the lung.

16. Brain edema is life-threatening; if the swelling is severe, the brain can herniate (extrude) through the foramen magnum. With increased intracranial pressure, the brain stem vascular supply can be compressed. Either condition can cause death by injuring the medullary centers

17. Hemorrhage Hemorrhage, defined as the extravasation of blood from vessels, occurs in a variety of settings. The risk of hemorrhage (often after a seemingly insignificant injury) is increased in a wide variety of clinical disorders collectively called hemorrhagic diatheses .

18. Trauma, atherosclerosis, or inflammatory or neoplastic erosion of a vessel wall also may lead to hemorrhage, which may be extensive if the affected vessel is a large vein or artery.

19. Manifestations of Hemorrhage Hemorrhage may be external or accumulate within a tissue as a hematoma, which ranges in significance from trivial (e.g., a bruise) to fatal. Large bleeds into body cavities are given various names according to location— hemothorax , hemopericardium , hemoperitoneum , or hemarthrosis (in joints ).

20. petechiae Petechiae are minute (1 to 2 mm in diameter) hemorrhages into skin, mucous membranes, or serosal surfaces, ; causes include low platelet counts (thrombocytopenia), defective platelet function.

21. Purpura and ecchymoses Purpura are slightly larger (3 to 5 mm) hemorrhages, causes include trauma, vascular inflammation ( vasculitis ), and increased vascular fragility. Ecchymoses are larger (1 to 2 cm) subcutaneous hematomas (colloquially called bruises).

22. Clinical significance of hemorrhage Depends on the volume of blood lost and the rate of bleeding . The site of hemorrhage also is important. Chronic or recurrent external blood loss (e.g., due to peptic ulcer) frequently culminates in iron deficiency anemia