Embolism, infraction, shock Flashcards
What are the 3 common circulatory disorders?
- Embolism
- Infraction
- Shock
What is the concept of Embolism?
- An embolus is a mass of material in the vascular system able to become lodged within a vessel and block its lumen
What is the most common type of embolism?
- Pulmonary embolism, from deep leg vein thrombosis
Where does the term thromboembolism come from?
- Most of the emboli are form dislodged thrombus, hence the term thromboembolism
What location is the outcome of Embolism?
- The outcome depends on where the emboli originate and where they lodge
What are the sources of emboli?
- Pieces of thrombus, mixed thrombus and blood clot
- Infected lesions within the bloodstream
- Gas bubbles e.g. air, N2 (divers transferred rapidly from high to low-pressure environments)
- Fat, bone marrow (in bone fractures)
- Tumour cells
- Others: amniotic fluid (during labour)
What % of Pulmonary Embolism are small and clinically silent?
- 60% - 80%
What can Pulmonary embolism cause?
- Can cause sudden death, right heart failure, cardiovascular collapse
- If the blockage is in a middle size vessel, it can cause pulmonary haemorrhage
- Multiple emboli over time may cause pulmonary hypertension
What is Systemic arterial emboli?
- Emboli arise in the arterial circulation
- ~80% from intracardiac mural thrombi
- ~10-15% of unknown origin
- Can travel to a wide variety of sites
- In general, arterial emboli cause tissue infraction
Systemic arterial emboli can travel to a wide variety of sites, what does the site of lodge depend on?
- The site of lodge depends on the source and the relevant amount of blood flow that downstream tissues receive
What is infraction?
- An infarct is an AREA of ISCHEMIC NECROSIS caused by OCCLUSION of either the ARTERIAL SUPPLY or the VENOUS DRAINAGE in a particular tissue
Explain the relationship of Tissue infraction and clinical illness and death
- Tissue infraction is a common and very important cause of clinical illness and death
Is death of tissue from toxins or trauma infraction?
- The death of tissue from other causes, such as toxins or trauma, is not infraction but simply necrosis
What do Infractions result from?
- Nearly 99% of all infracts result from thrombotic or embolic events and almost all result from arterial occlusion
- Other causes: vasospasm, haemorrhage into atheromatous plaque, vessel compression (by tumour), traumatic rupture
What does different shapes of infracts reflect?
- Shape reflects the territory of occluded blood supply
Name the different shapes of infracts and name the location of the blood supply
- Wedge-shaped: in lung
- Triangular: in kidney
- Scarred: in spleen
What is Classification of infracts?
- Classification: Based on their colour (reflecting the amount of haemorrhage) and the presence or absence of microbial infection
Explain the different colours of infracts
- White (anaemic): in solid organs with end arterial circulation (such as heart, spleen, and kidney)
- Red (haemorrhagic)
- Septic: Infected infract
- Bland: uninfected infract
Name and explain the major factors that influence the outcome of an infraction
- The nature of the vascular supply: The availability of alternative blood supply
- The rate at which an occlusion develops: Slow occlusion provides time for alternative perfusion pathways
- Vulnerability to hypoxia: Neurons and myocardial cells are vulnerable
- The oxygen content of the blood
Explain the Evolution of myocardial infract
- Infracted area varies in appearance depending on the time after infraction
What is Shock?
- A final common pathway for several lethal clinical events best described as inadequate tissue perfusion
What is Shock characterised by and this is due to what?
- Characterised by systemic hypotension due to:
- Reduced cardiac output
- Reduced effective circulating blood volume
What is Cardiogenic shock caused by?
- Cardiogenic shock: results from low cardiac output due to heart failure
What is the cause of Hypovolaemic shock?
- The result of low cardiac output due to the loss of blood or plasma volume
What is the cause of Septic shock?
- Results from vasodilation and peripheral pooling of blood as part of a systemic immune reaction to bacterial or fungal infection
What are the symptoms of shock
- Altered conscious state
- Restlessness or irritability
- Pale or bluish, cool moist skin
- Excessive thirst
- Rapid and weak pulse
- Rapid breathing
- Nausea and/or vomiting
What is the first aid of shock?
- Place the victim in a shock position
- Keep the person warm and comfortable
- Turn the victim’s head to one side if the neck injury is not suspected
