Haemodynamic disorders

Question 1

what is oedema?

Answer 1

an abnormal increase in interstitial tissue

Question 2

what 5 things can oedema be caused by?

Answer 2

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

Question 3

what does generalised oedema cause?

Answer 3

• left ventricular failure
• nephrotic syndrome
• hepatic failure

Question 4

what causes generalised oedema?

Answer 4

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

Question 5

what is pulmonary oedema caused by?

Answer 5

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

Question 6

what is the main symptom of pulmonary oedema?

Answer 6

breathlessness

Question 7

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

Answer 7

bacterial infection = acquiring pneumonia

Question 8

what is cerebral oedema usually caused by?

Answer 8

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

Question 9

what is the vasogenic cause of cerebral oedema?

Answer 9

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

Question 10

what is the cytotoxic cause of cerebral oedema?

Answer 10

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

Question 11

what is the osmotic cause of cerebral oedema?

Answer 11

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

Question 12

what is the interstitial cause of cerebral oedema?

Answer 12

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

Question 13

what is thrombosis?

Answer 13

abnormal blood clot formation in the circulatory system

Question 14

what 3 things is thrombosis caused by?

Answer 14

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

Question 15

what is venous thrombosis?

Answer 15

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

Question 16

what is a potential complication of DVT?

Answer 16

pulmonary embolism

Question 17

what is coronary artery thrombosis?

Answer 17

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

Question 18

what is cardiac thrombosis?

Answer 18

abnormal cardiac contractibility where stasis is the key factor

Question 19

what is an embolus?

Answer 19

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

Question 20

describe the formation of a venous thrombo-embolism

Answer 20

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

Question 21

what is an infarct?

Answer 21

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

Question 22

what is a red infarct?

Answer 22

mostly by venous occlusion

Question 23

what is a white infarct?

Answer 23

arterial occlusion

Question 24

how does an infarct heal?

Answer 24

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

Question 25

what is a myocardial infarction?

Answer 25

obstruction in coronary artery

Question 26

what is a cerebral infarction?

Answer 26

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

Question 27

what is a bowel infarction?

Answer 27

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

Question 28

what is a haemorrhage?

Answer 28

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

Question 29

what can rupture of a major vessel cause?

Answer 29

acute haemorrhage with risk of hypovolaemia, shock and death

Question 30

why can rupture of a small vessel be fatal?

Answer 30

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

Question 31

what can cerebral haemorrhage cause?

Answer 31

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

Question 32

what is shock?

Answer 32

failure of tissue perfusion

Question 33

what is shock caused by?

Answer 33

• pump failure

- peripheral circulation failure

Question 34

what organs are most vulnerable to shock?

Answer 34

brain, lungs, heart, kidneys, bowel

Question 35

what is sepsis?

Answer 35

systemic inflammatory response syndrome (SIRS) + infection

Question 36

what is severe sepsis?

Answer 36

sepsis + organ hypoperfusion

Question 37

what is septic shock?

Answer 37

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

Question 38

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

Answer 38

gram +ve > gram -ve > fungi