Cell Pathology 1 - Haemodynamic Disorders Flashcards
What is oedema?
An abnormal increase in interstitial fluid
What are the aetiologies (causes) of oedema?
- Increased hydrostatic pressure
- Salt and H2O retention
- Reduced plasma oncotic pressure
- Inflammation
- Lymphatic obstruction
What are the two types of oedema?
- Generalised oedema (fluids in serious cavities)
- Localised oedema (pulmonary and cerebral oedema)
How much larger must the amount of interstitial fluid be for generalised oedema? Where is it found?
- > 5L
- Pleural, pericardial, peritoneal cavities
What are the effects of generalised oedema?
- Left heart failure
- Inflammation
- Venous hypertension
- Lymphatic obstruction
What can localised oedema cause?
- Congestive heart failure
- Hypoproteinaemia (low protein content)
- Nutritional oedema
What is generalised pitting oedema?
- Widespread accumulation of fluid in subcutaneous cavities
- Pitting oedema is observable swelling of body tissues due to fluid accumulation that may be demonstrated by applying pressure to the swollen area (such as by depressing the skin with a finger).
What is pulmonary oedema?
- Left heart failure increases the hydrostatic pressure in the pulmonary capillary bed
- Fluid accumulates first in the interstitial space and then spills into alveolar spaces
What are the symptoms of pulmonary oedema?
- Breathlessness (dysponea)
- Breathlessness is worse when lying flat (orthopnoea)
- Fluid In alveolar spaces predisposes to bacterial infection in the lung (pneumonia)
What is cerebral oedema?
- Localised oedema
- Vasogenic (increased permeability of capillaries and valves)
- Cytotoxic (derangement of sodium/potassium pumps for example in ischaemic strokes)
What is thrombosis?
- Abnormal blood clot formation in the circulatory system
What is virchows triad in thrombosis?
- Endothelial injury
- Stasis or turbulent blood flow
- Blood hypercoaguability
What is venous thrombosis& and it’s possible complications?
- Stasis and hypercoagulability are key factors
- Form in deep leg vains mostly
- Pulmonary embolism is the most important potential complication
What is arterial thrombosis? What are the potential complications?
- Related to vessel wall injury caused by atherosclerotic plaques
- Narrowing of the artery (stenosis) causes ischaemia of the tissue supplied by the artery
- Complete blockage (occlusion) causes infarction of the tissue supplied by the artery
What are the fates of thrombi?
- Propagation (becomes larger)
- Embolism (small piece of clot breaks off)
- Dissolution (removed to allow normal blood flow)
- Organisation and recanalisation (body’s inflammatory response fixes the thrombi)
When do thrombi come to clinical attention?
When they obstruct arteries or veins& or give rise to emboli.
What is an emboli?
- Abnormal material within the circulatory system that is carried in the blood to a site distant from its point of origin
- Often dislodged thrombus
- May be fat& amniotic fluid or a tumour
- Can lodge in vessels and block them off
What is an infarct?
- An area of ischaemic necrosis caused by occlusion
- Red infarct by venous occlusion
- White infarct by arterial occlusion
- Heal by repair (maintains structural integrity& but loss of functional tissue)
What is a venous thromboembolism?
An embolism originating from deep veins
What are the symptoms of a pulmonary thromboembolism?
- Emboli lodging in a major pulmonary artery - causing immediate death
- Emboli in medium arteries cause breathlessness
- Emboli in small arteries cause breathlessness& chest pain& and dizziness
- Risk of death increases the longer it takes to diagnose
What is a haemorrage?
- Extravasion of blood due to vessel rupture (trauma/intrinsic disease of the blood vessel)
- Rupture of a major vessel causes acute haemmorage with risk of hypovolaemia& shock and death
What are the types of shock?
- Hypovolemic
- Cardiogenic
- Anaphylactic
- Sepsis
- Neurogenic
What is hypovolaemic shock?
- Due to fluid loss
- Loss of over 1L of blood
- Mostly affects kidney, brain and skin
What is cardiogenic shock?
- Heart can’t pump enough blood to meet the body’s demands
- Caused by acute myocardial infarction
- High mortality rate
What is septic shock?
Systematic inflammatory response syndrome + infection + organ hyperfusion despite fluid resuscitation, or use of vasopressors.
What are the complications of sepsis?
- Organ dysfunction
- Multi-organ failure
- Ischemic tissue
- Acute tubular necrosis
What causes septic shock?
Gram positive > gram negative > fungi
Release of endotoxins:
- Activates compliment pathway
- Damages endothelial cells
- Tumour necrosis factor
