Haemodynamic disorders Flashcards Preview

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Flashcards in Haemodynamic disorders Deck (38):
1

what is oedema?

an abnormal increase in interstitial tissue

2

what 5 things can oedema be caused by?

- increased hydrostatic pressure
- salt and water retention
- reduced plasma osmotic pressure
- lymphatic obstruction
- inflammation

3

what does generalised oedema cause?

- left ventricular failure
- nephrotic syndrome
- hepatic failure

4

what causes generalised oedema?

low renal blood flow results in an increase in renin secretion which causes the transformation of angiotensinogen to angiotensin I

the precursor hormone angiotensin I is converted to the active hormone angiotensin II by angiotensin-converting enzyme (ACE), which promotes the secretion of aldosterone from the adrenal cortex, resulting in retention of sodium and water in the kidneys

5

what is pulmonary oedema caused by?

raised hydrostatic pressure in the pulmonary capillary bed most commonly due to left ventricular failure

6

what is the main symptom of pulmonary oedema?

breathlessness

7

what does fluid in the alveolar spaces increase the risk of?

bacterial infection = acquiring pneumonia

8

what is cerebral oedema usually caused by?

disruption to the cerebral capillaries that can be vasogenic, cytotoxic, osmotic or interstitial

9

what is the vasogenic cause of cerebral oedema?

breakdown of blood-brain barrier (e.g. due to trauma/tumours)

10

what is the cytotoxic cause of cerebral oedema?

abnormalities in sodium-potassium pump (e.g. due to ischaemic stroke)

11

what is the osmotic cause of cerebral oedema?

reduction in plasma osmolality (e.g. due to SIADH)

12

what is the interstitial cause of cerebral oedema?

breakdown of cerebrospinal fluid-brain barrier (e.g. due to obstructive hydrocephalus)

13

what is thrombosis?

abnormal blood clot formation in the circulatory system

14

what 3 things is thrombosis caused by?

- changes in the intimal surface of a blood vessel
- changes in blood constituents
- changes in pattern of blood flow

15

what is venous thrombosis?

thrombosis mainly occurring in deep leg veins (DVT) where stasis and hyper-coagulability are key factors

16

what is a potential complication of DVT?

pulmonary embolism

17

what is coronary artery thrombosis?

complete blockage of the artery by thrombus, possibly due to haemorrhage within an atherosclerotic plaque, which can cause MI

18

what is cardiac thrombosis?

abnormal cardiac contractibility where stasis is the key factor

19

what is an embolus?

a detached mass (usually fragments of dislodged thrombus but may be fat/air/tumour) within the circulatory system that is carried in the blood to a site far from its point of origin, where it can lodge in vessels and block them off = embolism

20

describe the formation of a venous thrombo-embolism

1) blood clot forms in veins, breaks free and travels to the heart
2) embolus travels through the heart and blocks blood vessel in the lung
3) emboli either:
- lodges in a major pulmonary artery causing instant death
- lodges in a medium sized artery causing breathlessness
- lodges in small arteries causing subtle symptoms of breathlessness, chest pain and dizziness

21

what is an infarct?

tissue necrosis due to ischaemia (normally becuase of the obstruction of an artery)

22

what is a red infarct?

mostly by venous occlusion

23

what is a white infarct?

arterial occlusion

24

how does an infarct heal?

by repair - structural integrity is maintained but there is permanent loss of tissue function

25

what is a myocardial infarction?

obstruction in coronary artery

26

what is a cerebral infarction?

emboli from heart or carotid artery, most common in the middle cerebral artery

27

what is a bowel infarction?

emboli often from heart, and migrates through the aorta into the superior mesenteric artery

28

what is a haemorrhage?

leakage of blood due to vessel rupture, due to trauma or an intrinsic disease

29

what can rupture of a major vessel cause?

acute haemorrhage with risk of hypovolaemia, shock and death

30

why can rupture of a small vessel be fatal?

if it occurs at a vital site (e.g. brainstem)

31

what can cerebral haemorrhage cause?

- solid haematoma in cranial cavity which can be fatal
- rise in intercranial pressure
- tonsillar herniation

32

what is shock?

failure of tissue perfusion

33

what is shock caused by?

- pump failure
- peripheral circulation failure

34

what organs are most vulnerable to shock?

brain, lungs, heart, kidneys, bowel

35

what is sepsis?

systemic inflammatory response syndrome (SIRS) + infection

36

what is severe sepsis?

sepsis + organ hypoperfusion

37

what is septic shock?

severe sepsis + hypoperfusion despite adequate fluid resuscitation, or the use of vasopressors to maintain blood pressure

38

what is the order of cause of septic shock from pathogens?

gram +ve > gram -ve > fungi