Embolism, infarction, shock

Question 1

what is an embolus

Answer 1

a mass of material in he vascular system able to BECOME LODGED within a vessel and BLOCK ITS LUMEN

Question 2

what is the most common embolism

Answer 2

PULMONARY EMBOLISM (from DVT)

Question 3

what are sources of embolism

Answer 3

• pieces of thrombus, mixed thrombus and blood clot
• INFECTED LESIONS within blood stream
• gas bubbles (air, N2)
• fat, bone marrow (from fractures)
• tumour cells
• others: amniotic fluid (esp during labour)

Question 4

describe pulmonary emboli
where are they from
what does it cause

Answer 4

• most are SMALL and CLINICALLY SILENT
• most from DVT
• can cause: sudden death, RIGHT heart failre, cardiovascular collapse, PULMONARY HAEMORRHAGE: if in a middle sized vessel
• if MULTIPLE EMBOLI, may cause PULMONARY HYPERTENSION

Question 5

describe systemic arterial emboli
what do they arise from
what are the origins
what does it cause

Answer 5

• arises from ARTERIAL CIRCULATION
• ~80% from intracardiac mural thrombi (attach to wall of blood vessel)
• ~10-15% of unknown origin
• generally causes TISSUE INFARCTION/GANGRENE

Question 6

what is infarction

Answer 6

an AREA of ISCHAEMIC NECROSIS caused by OCCLUSION of either the ARTERIAL SUPPLY or VENOUS DRAINAGE in a particular tissue

Question 7

what is the main (99%) cause of infarcts

Answer 7

THROMBOTIC or EMBOLIC events- ARTERIAL OCCLUSION 
Other:
- vasospasm 
- haemorrhage into atheromatous plaque
- vessel compression (by tumour) 
- traumatic rupture

Question 8

what does the shape of an infarct reflect
lung
kidney
spleen

Answer 8

the TERRITORY of occluded blood supply
lung - wedge shaped
kidney - triangular
spleen - scarred

Question 9

how are infarcts classified

Answer 9

• based on COLOUR (which reflects amount of haemorrhage) and presence or absence of MICROBIAL INFECTION

Question 10

what does a white infarct mean

where

Answer 10

• anaemic

- in SOLID organs w/ end arterial circulation (heart, spleen, kidney)

Question 11

what does a red infarct mean

Answer 11

haemorrhagic

Question 12

what does a septic infarct mean

Answer 12

infected infarct

Question 13

what does a bland infarct mean

Answer 13

uninfected infarct

Question 14

which factors influence the outcome of an infarct

Answer 14

• nature of vascular supply (availability of alternative blood supply)
• rate at which occlusion develops (if slow occlusion, more time for alt perfusion pathways)
• vulnerability to hypoxia (neurons and myocardial cells= vulnerable)
• oxygen content of blood

Question 15

how does the infarct area’s appearance vary with time

Answer 15

6h after infarct: no visible changes
24h: pallor visible, inflammation ata edge
days/weeks: macrophage infiltration + fibrosis
months: fibrous scar

Question 16

what is shock

Answer 16

a final common pathway for several lethal clinical events best described as INADEQUATE TISSUE PERFUSION

Question 17

what characterises shock

Answer 17

SYSTEMIC HYPOTENSION due to:

• REDUCED CARDIAC OUTPUT
• REDUCED EFFECTIVE CIRCULATING BLOOD VOLUME

Question 18

what causes cardiogenic shock

Answer 18

results from low cardiac output due to heart failure

Question 19

what causes hypovolaemic shock

Answer 19

low cardiac output due to loss of blood or plasma volume

Question 20

what causes septic shock

Answer 20

results from vasodilation and peripheral pooling of blood as part of a systemic immune reaction to bacterial or fungal infection

Question 21

what are the symptoms of shock

Answer 21

• altered conscious state
• pale, bluish or moist skin
• restlessness or irritability
• excessive thirst
• rapid and weak pulse
• nausea/vomiting

Question 22

what is the first aid of shock

Answer 22

• place victim in shock position
• keep person warm and comfy
• turn head to one side (if no injury suspected)