Ischaemia, infarction and shock

Question 1

Define hypoxia

Answer 1

any state of reduced tissue oxygen availability

Question 2

Define ischaemia

Answer 2

pathological reduction in blood flow to tissues

Question 3

Are the effects of ischaemia reversible?

Answer 3

only if limited/for a short duration (otherwise cell death occurs)

Question 4

How can the effects of ischaemia be reversed?

Answer 4

with therapueutic reperfusion

Question 5

Does therapeutic reperfusion have an effect on infarcted tissue?

Answer 5

no

Question 6

Define infarction

Answer 6

ischaemic necrosis caused by occlusion of the arterial supply or venous drainage

Question 7

Define infarct

Answer 7

an area of infarction in tissues

Question 8

What are the 2 most common causes of infarction?

Answer 8

thrombosis and embolism

Question 9

Name some less common causes of infacrtion (5)

Answer 9

vasospasm, atheroma expansion, extrinsic compression, twisting of vessel roots, rupture of vascular supply

Question 10

Describe red infarction

Answer 10

haemorrhagic - dual blood supply/venous infacrtion

Question 11

Describe white infarction

Answer 11

anaemic - single blood supply hence totally cut off

Question 12

What shape are most infarcts?

Answer 12

wedge

Question 13

What four factors influence the degree of ischaemic damage?

Answer 13

nature of blood supply, rate of occlusion, tissue vulnerability to hypoxia, blood oxygen content

Question 14

If there is an alternative blood supply, will the damage be more or less?

Answer 14

Less

Question 15

Why are the kidneys, spleen and testis vulnerable to infarction?

Answer 15

they have single blood supplies

Question 16

Are slow developing occlusions more or less likely to infarct tissues?

Answer 16

less likely

Question 17

Why are slow developing occlusions less likely to infarct tissues?

Answer 17

allows time for development of alternative (collateral) perfusion pathways

Question 18

What does ischaemia in the heart cause?

Answer 18

ischaemic heart disease (angina, MI)

Question 19

What does ischaemia of the brain cause?

Answer 19

cerebrovascular disease (TIA/CVA)

Question 20

What does ischaemia of the intestines cause?

Answer 20

ischaemic bowell

Question 21

What does ischaemia of the extremities cause?

Answer 21

peripheral vascular disease/gangrene

Question 22

What is meant by cerebrovascular disease?

Answer 22

Any abnormality in the brain caused by a pathological process involving the blood vessels

Question 23

What causes ischaemic stroke?

Answer 23

thrombosis secondary to atherosclerosis r embolism

Question 24

What causes haemorrhagic stroke?

Answer 24

intracerebral haemorrhage or ruptured aneurysm in circle of Willis

Question 25

What is dry gangrene?

Answer 25

ischaemic coagulative necrosis only

Question 26

What is wet gangrene?

Answer 26

superimposed infection

Question 27

What is gas gangrene?

Answer 27

superimposed infection with gas producing organism

Question 28

What is gangrene?

Answer 28

Infarction of entire portion of limb/organ

Question 29

Define shock

Answer 29

a physiological state characterised by a significant reduction of systemic tissue perfusion resulting in decreased oxygen delivery to tissues

Question 30

how does shock lead to cellular hypoxia?

Answer 30

impaired tissue perfusion and prolonged oxygen deprivation

Question 31

What are the cellular effects of shock? (5)

Answer 31

- membrane ion pump dysfunction - intracellular swelling - leakage of intracellular contents - inadequate regulation of intracellular pH - anaerobic respiration

Question 32

What are the systemic effects of shock? (4)

Answer 32

- alterations in the serum pH - endothelial dysfunction - stimulation of inflammatroy and anti-inflammatory cascades - end-organ damage

Question 33

What is hypovolaemic shock?

Answer 33

intra-vascular fluid loss

Question 34

What effects does hypovolaemic shock have?

Answer 34

decreased venous return to heart, decreased stroke volume

Question 35

How do you compensate for the effects of hypovolaemic shock?

Answer 35

increase systemic vascular resistance

Question 36

What causes hypovolaemic shock?

Answer 36

haemorrhage, diarrhoea, vomitting

Question 37

What is third spacing?

Answer 37

acute loss of fluid into internal body cavities

Question 38

What is cardiogenic shock?

Answer 38

cardiac pump failure

Question 39

What are the effects of cardiogenic shock and how do you compensate for this?

Answer 39

decreased cardiac output, combatted by increasing systemic vascular resistance

Question 40

What are the 4 categories of cardiogenic shock?

Answer 40

myopthic, arrythmia-related, mechanical, extra-cardiac

Question 41

What cause myopathic cardiogenic shock?

Answer 41

MI

Question 42

What causes mechanical cardiogenic shock?

Answer 42

valvular defects, ventricular septal defects

Question 43

What causes extra-cardiac cardiogenic shock?

Answer 43

anything that imparis cardiac filling or ejection of blood from heart

Question 44

What is distributive shock?

Answer 44

decreased systemic vascular resistance sue to severe vasodilation

Question 45

Which type of shock are all of the following?: | septic shock, anaphylactic shock, neurogenic shock, toxic shock syndrome

Answer 45

distributive shock