Hemodynamic disorders and normal and abnormal hemostasis Flashcards
What is maintained in normal fluid homeostasis?
- Vascular wall integrity
- Intravascular hydrostatic pressure
- Osmolarity
What is edema?
Where does it accumulate?
The accumulation of interstitial fluid in tissues
Subcutaneous tissues, body cavities (pleural cavity, pericardial cavity, peritoneal cavity)
What is anasarca?
Very severe generalized edema
What is the normal fluid balance?
2/3 intracellular
1/3 extracellular (interstitial)
with only 5% of extracellular fluid in vessels: blood plasma
What factors affect fluid balance?
Vascular hydrostatic pressure
Plasma colloid osmotic pressure (due to plasma proteins-albumin, globulin)
Lymphatic vessels pick up any residual
What causes edema?
- Increased hydrostatic pressure
- Decreased plasma osmotic pressure
- Lymphatic obstruction (lymphedema)
- Sodium (and water) retention
How does increased hydrostatic pressure occur?
Increased capillary pressure as a result of either venous obstruction or impaired venous return.
What are local examples of venous obstruction or impaired venous return? (leading to edema)
Deep vein thrombosis, mass lesion, lower extremity inactivity, cirrhosis
What is an example of a generalized venous obstruction or impaired venous return? (leading to edema)
Congestive heart failure.
Which also results in hypoperfusion of kidneys causing secondary hyperaldosteronism
What is another way that hydrostatic pressure can cause edema?
Arteriolar dilatation
as a result of Heat or Neurohumoral dysfunction (hypothalamic damage/malfunction)
How can edema occur from reduced plasma osmotic pressure?
Excessive loss of albumin leads to decreased intravascular volume and secondary hyperaldosteronism. (Albumin is the serum protein most responsible for maintaining colloid osmotic pressure)
What can cause albumin loss?
Nephrotic syndrome (protein-losing)
Protein-losing enteropathy (IBS, GI infections)
Malnutrition
Liver disease (reduced synth like cirrhosis)
How can lymphatic obstruction (lymphedema) cause edema?
Inflammatory
Neoplastic
Post-surgical/post radiation (removing lymphatic channels)
How does sodium (and water) retention occur?
Excessive salt intake w/ renal insufficiency
or
Acute reduction of renal function (like glomerulonephritis)
What causes subcutaneous edema?
Congestive heart failure and renal failure
What causes pulmonary edema?
Left ventricular failure
What causes edema of the brain?
Tumors cause focally
Viral infections cause diffusely
What is hyperemia?
An increase in blood volume within a tissue due to increased blood flow and arteriolar dilation.
An ACTIVE process.
Occurs at sites of inflammation
What is congestion?
An increase in blood volume within a tissue due to decreased/impaired outflow of venous blood.
A PASSIVE process
May occur systematically (liver and lung congestion due to heart failure) or locally (ex: obstruction of superior sagittal sinus of dura)
What are the two phases of clotting in normal hemostasis?
Primary and Secondary
What is important to the primary phase of clotting in normal hemostasis?
- Vasculature
- Blood flow
- Platelet count and function
- Extracellular matrix proteins
What is important to the secondary phase of clotting in normal hemostasis?
- Platelet plug
2. Coagulation factors
What are the important steps to primary hemostasis?
- Platelet adhesion
- Shape change
- Granule release
- Recruitment
- Aggregation
What are the important steps to secondary hemostasis?
- Tissue factor
- Phospholipid complex expression
- Thrombin activation
- Fibrin polymerization
What are important laboratory screenings for primary hemostasis?
- Platelet count
- Platelet function (PFA-100 and platelet aggregation studies)
- vWillebrand studies (vW antigen and vW activity)