Haemodynamic disorders

Question 1

What is oedema?

Answer 1

Abnormal increase in interstitial fluid

Question 2

Describe the pressures in tissues:

Answer 2

At arterial end, hydrostatic pressure > oncotic pressure.
- Fluid leaves circ
At venous end, oncotic pressure > hydrostatic pressure.
- Fluid re-enters venule

Question 3

What are the aetiologies of oedema?

Answer 3

Increased hydrostatic pressure - impaired venous return / heart failure

Salt/H2O retention - protein losing enteropathy/glomerulonephritis etc.

Reduced plasma oncotic pressure

Inflammation - sepsis or localised

Lymphatic obstruction - accumulation of fluid

Question 4

What is generalised oedema?

Answer 4

In serous cavities, >5L; caused by left heart failure (that then causes right heart failure), inflammation, venous hypertension or lymphatic obstruction (after radiotherapy/surgery)

Question 5

What is Generalised pitting oedema?

Answer 5

Widespread accumulation in subcutaneous tissue e.g. In feet as gravity draws down - causes pits when pressure applied

Question 6

What is localised oedema?

Answer 6

Pulmonary and cerebral; caused by congestive heart failure (L&R), low protein content or nutritional oedema

Question 7

What is pulmonary oedema?

Answer 7

Normally plasma oncotic pressure > hydrostatic pressure in pulmonary capillaries, but left heart failure increases hydrostatic pressure in pulmonary capillary bed, so fluid accumulates in interstitial and then alveolar space

Question 8

What are the symptoms of pulmonary oedema?

Answer 8

Dyspnoea (breathlessness), worse when lying flat

Question 9

What an pulmonary oedema lead to?

Answer 9

Fluid in alveolar spaces predisposes to bacterial infections (pneumonia)

Question 10

What is cerebral oedema?

Answer 10

Midline shift can occur; two causes: cytotoxic (derangement of Na+/K+-ATPase pumps) and vasogenic (increased permeability of capillaries and venules)

Question 11

What is a thrombosis?

Answer 11

Abnormal clot ofrmation caused by:
-endothelial injury
-stasis/turbulent flow
-hyprcoadulability
(Virchow's triad)

Question 12

What are the 4 fates of thromboses?

Answer 12

Propagation (get bigger)
Embolise
Dissolve
Organise and recanalisation

Question 13

What is an embolus?

Answer 13

Abnormal material within circulatory system carried to site distant from origin; most fragments of a dislodged thrombus (thromboemboli) but can be caused by fait, air, tumours or amniotic fluid; can lodge in larger vessels and block them off

Question 14

What is an infarct?

Answer 14

Area of ischaemic necrosis caused by the occulsion of arterial supply or venous drainage

Question 15

What is a Red infarct?

Answer 15

Caused by venous occlusion - organs w/dual circulation

Question 16

What is a white infarct?

Answer 16

Caused by arterial occlusion - solid organs (spleen, kidneys)

Question 17

Describe the repair of infarcts:

Answer 17

Fibrosis instead of original cells; preserves structural integrity, but permanent loss of functional tissue

Question 18

What triad signals a ruptured AAA

Answer 18

Back pain
Hypotension
Pulsatile mass

Question 19

What syndrome predisposes you to a AAA?

Answer 19

Marfans

Question 20

What is hypovolaemic shock?

Answer 20

More than 1L blood loss, most perfused organs will shut down

Question 21

What is cardiogenic shock?

Answer 21

Heart cannot pump enough blood to meet demands, caused by acute MI