Haemodynamic Disorders Flashcards
Define oedema, list its causes, list types based on location
- An abnormal increase in the volume of interstitial fluid
- Caused by raised hydrostatic pressure, reduced osmotic pressure, or disruption to capillary bed
- May be localised or generalised
Summarise pulmonary oedema
- Result of raised pulmonary capillary hydrostatic pressure due to pulmonary venous congestion
- Caused by left ventricular failure
- Consequences - Breathlessness and susceptibility to pneumonia.
Summarise cerebral oedema
- Result of breakdown of normal capillary barrier.
- Occurs in brain tissue around lesions
- Consequences - Rise in intracranial pressure which can be fatal.
Summarise generalised oedema
- Pathogenesis complex and multifactorial
- Caused by left ventricular failure, hepatic failure, and nephrotic syndrome
- Consequences - Pitting peripheral oedema, pleural effusions, and ascites.
Define thrombosis
An abnormal blood clot formation within the circulatory system
Cause of thrombosis
Abnormal activation of the haemostat system
List the types of thrombosis
- Arterial
- Venous
- Cardiac
Consequences of thrombosis
- Can completely resolve
- Can undergo organisation and recanalisation
- Can become significant by occluding a vessel or embolising.
Define embolus
A detached mass within the blood that moves through the circulatory system to a point distal from the origin
Cause of emboli
Fragmentation of dislodged thrombi (form thromboemboli)
Types of emboli
Arterial thromboemboli
Venous thromboemboli
Impact sites and consequences of arterial and venous thromboemboli
- Cerebral arteries - Stroke
- Mesenteric arteries - Small bowel infarction
- Lower limbs - Acute lower limb ischaemia
- Venous - travel via heart into pulmonary arteries - pulmonary embolism
Rare types of emboli
Fat
Septic
Amniotic fluid
Define infarction
Tissue necrosis due to ischaemia
Causes of infarction
- Most caused by obstruction of artery, either by thrombosis or a thromboembolus e.g. acute MI and cerebral infarction (stroke)
- Venous obstruction - tissue massively suffuse with blood.
Long-term consequences of infarction
Heal by pair
- Permanent loss of functional tissue
Causes of haemorrhage
Traumatic rupture or intrinsic disease of the vessel.
Possible consequences of haemorrhage
- Major vessel rupture causes acute haemorrhage with risk of hypovolaemia, shock and death.
- Small bleeds in vital sites can be fatal = brainstem haemorrhage.
- Solid hematomas in cranial cavity raises intracranial pressure, increases risk of tonsillar herniation.
- Chronic low grade haemorrhage may present with iron deficiency anaemia.
Define shock
A generalised failure of tissue perfusion (decreased or absent flow of blood/fluid to organs)
Causes of shock
- Failure of pump mechanism - Acute MI, problems with peripheral circulatory system, hypovolaemia
- Collapse of circulatory system can occur causing ischaemia - Most vulnerable organs are heart, brain, bowel, and lungs.
