Hemodynamics (2/25, Rizea) Flashcards
Capillary fluid exchange is dependent on the balance of what two variables?
Balance of:
- hydrostatic pressure
- oncotic plasma protein pressure
- Fluid, salts, organic molecules move from intravascular space to the interstitial space (aka out of the capillary bed) when the hydrostatic pressure within the capillary bed (32 mmHg) exceeds the plasma colloid osmotic pressure (26 mmHg).
- Reverse: Fluid, salts, organic molecules move back into the vascular lumen (aka back into the venous end of the capillary bed) when the colloid osmotic pressure (26 mmHg) exceeds the hydrostatic pressure (20 mmHg)
What determines total extracellular fluid volume?
Total body sodium!
Renal sodium excretion es muy importante.
What is edema?
Accumulation of excess fluid in interstitial tissue or in cavities.
What are the 4 main mechanisms of edema (the pathogenesis)?
- Increased hydrostatic pressure
- Decreased plasm oncotic pressure
- Increased capillary permeability
- Lymphatic obstruction
What might cause a hydrostatic pressure increase and eventually lead to edema (3 causes)?
- Arteriolar dilation (example: inflammation)
- Increased venous pressure due to obstruction (example: venous thrombosis)
- Increased blood volume
What might cause a decrease in plasma oncotic pressure (3 causes)?
- Nephrotic syndrome (kidney disorder)
- Cirrhosis
- Malnutrition
What might cause an increase in capillary permeability (4 causes)?
- Acute inflammation
- Allergic Reactions
- Burns
- Shock
What might cause a lymphatic obstruction (3 causes)?
- Malignancy
- Fibrosis post radiation or inflammation
- Post surgery
What is the term for the fluid accumulation in serosal cavities?
Pericardial, pleural, or peritoneal effusion.
What might a transudative effusion indicate?
Transudative effusion = low protein. May indicate heart failure.
What might exudative effusion indicate?
Exudative effusion = high protein content. May indicate the presence of a tumor or inflammation.
Give 5 examples of localized edema:
- Inflammation
- Venous obstruction
- Lymphatic obstruction
- Allergic reaction
- Burns
Give 3 examples of generalized edema:
- Cardiac Failure
- Nephrotic syndrome
- Malnutrition
What does pulmonary edema suggest?
Left heart failure
What does lower limb edema suggest?
Right heart failure
What is cerebral edema a secondary symptom of?
Brain trauma, meningitis, infarcts, tumors
Define thrombosis:
The formation of an intravascular solid mass within the heart or intravascular system.
Created by the blood constituents: platelets, fibrin, entrapped red and white blood cells.
Adheres to luminal surface of the vessel
What are the 3 main predisposing factors for the formation of a thrombus?
- Endothelial damage
- Change in blood flow
- Change in blood coaguability
Name examples (5) of endothelial damage that may contribute to the formation of a thrombus:
- Trauma
- Inflammation
- Atherosclerosis
- Endocarditis
- Myocardial infarct
Name reasons (7) for a change in blood flow that may contribute to the formation of a thrombus:
- Narrowed arteries
- Aneurysms
- Cardiac arrhythmias
- Prolonged bedrest
- Postoperative
- Cardiac failure
- Myocardial infarction
Name 4 reasons for a change in blood coaguability that may contribute to the formation of a thrombus:
- Polycythemia (high hematocrit)
- Oral contraceptives
- Malignancy
- Coagulation abnormalities
What are the 5 outcomes of a thrombus?
- Propagation (growth) of the thrombus
- Occlusion of a vessel lumen
- Recanalization and organization
- Thromboembolism
- Fibrinolysis
What is the recanalization of a thrombus?
Recanalization is the ingrowth of endothelial cells, smooth muscle cells, and fibroblasts into the thrombus.
It provides capillary-sized channels through the thrombus for continuity of blood flow through the entire thrombus.
Define thromboembolism:
Part or all of the thrombus detaches and is transported elsewhere.
What is fibrinolysis?
Fibrinolysis is a natural process that breaks down fibrin clots.
For a newly formed thrombus, can use Rx to dissolve the newly formed thrombus.
What are two main clinical outcomes of a thrombus?
Ischemia and Infarction
Define embolism:
The transportation of a detached intravascular particle or mass in the bloodstream as far as its size will allow, where it becomes lodged and obstructs the vessel.
Can an embolism be anything other than a solid particle?
Yes - it can be solid, liquid, or a gas.
Where do arterial emboli originate and travel?
Originate: left atrium
Enter systemic circulation (brain, intestine, legs, kidney, spleen…think: BILKS)