Week 4 - Pathophysiology of Congestion and Oedema Flashcards
What is congestion?
excess of blood in vessels, leading to distended organs
What causes congestion?
its a secondary phenomenon - caused by something else.
What does a distended area present as?
hot, tender and swollen
What are 3 clinical examples of congestion causes?
- local acute congestion like DVT
- local chronic congestion like hepatic cirrhosis
- generalised acute congestion like congestive cardiac failure
How does a local acute congestion arise?
DVT example. blocks vein, so blood backs up in veins and pressure rises. less flow.
How does local chronic congestion arise?
hepatic cirrhosis. liver cells are destroyed, leading to fibrosis and inability for them to function normally. blood flow changes and is restricted, so blood must flow through portal-systemic shunt to bypass hepatic vessels.
How does generalised acute congestion arise?
congestive heart failure example. both sides of heart fail, so pulmonary and systemic circulations both have backflow, increased pressure and congestion. additionally, lack of blood to kidneys triggers renin-angiotensin-aldosterone system to retain fluid and increase volume of blood, increasing congestion. give diuretics.
What is hepatic central venous congestion?
blood moved through liver, through hepatic veins to the central vein, draining directly into IVC. if you have increased pressure in IVC, pressure increases in central vein, so backlog of blood into portal veins. they lack blood and o2 so only have energy to become fat cells.
What is the cause of oedema?
imbalance between haemodynamic forces and permeability of endothelium
What are 2 forms of oedema?
transudate and exudate oedema.
What are the haemodynamic forces involved in the microcirculation? What drives them?
capillary hydrostatic pressure and colloid oncotic pressure. driven by protein (albumin) gradient
What is a cause of exudate oedema?
capillary permeability change. more pores, larger proteins and molecules can exit, acute inflammation.
What is the process of pulmonary oedema?
left ventricular failure. blood backs into pulmonary veins and lungs, and hydrostatic pressure increases, pushing fluid out, into alveoli.
What is the process of peripheral oedema?
right heart failure. blood backs into veins, causing high pressure in systemic circulation, and hydrostatic pressure pushes fluid out. filtration.
What is the process of lymphatic blockage?
blocked/dysfunctional lymph nodes prevent lymph drainage, so lymph capillaries have great hydrostatic pressure. occurs in radiotherapy for breast cancer - axilla damaged and fibrosis occurs so cant drain lymph, leading to oedema in upper limb
