Thrombosis, embolism and shock

Question 1

Thrombosis

Answer 1

The formation of a solid or semi-solid mass from the

constituents of the blood while moving within the vascular system during life.

Question 2

Locations where thrombi may form

Answer 2

Arteries
Veins
Capillaries

Question 3

Factors that promote thrombosis

Answer 3

Virchow’s triad:

1. Abnormalities of the vessel wall
2. Abnormalities of blood flow
3. Abnormalities of the blood’s constituents

Question 4

Abnormalities of the vessel wall

Answer 4

Heart-
Myocardial infarction
Rheumatic endocarditis
Veins-
    Trauma
    Inflammation
    Chemicals -  sclerosants
		     (irritant substances injected
		      to obliterate varicose veins)
		     glucose
		     (atheroma in diabetes mellitus)
Capillaries-
    Inflammation

Question 5

Abnormalities of blood flow

Answer 5

Arteries-
Turbulence
	aneurysms, plaques, spasm
Heart- 
Atrial fibrillation
Aneurysms
Veins- 
Local problem
			compression
			inactivity
(postoperative bed rest; economy class syndrome)
General problem
			heart failure
			circulatory shock

Question 6

Abnormalities of the blood constituents

Answer 6

Increased viscosity
Polycythaemia
	Dehydration
	Chronic hypoxia
	Polycythaemia rubra vera
Hyperproteinaemia
	Multiple myeloma
(Tumour of plasma cells in bone marrow with accumulation of immunoglobulins in plasma)
Abnormalties of clotting
	Pregnancy  (prevents bleeding when placenta detaches)
	Some (older) contraceptive pills
	Following trauma   (liver produces more clotting factors)
Thrombocythaemia
Tumours
Inherited

Question 7

Fate of thrombi

Answer 7

Resolution
Fibrinolysis. Very common fate.
Organisation
Incorporation into a scar (mural nodule or web)
by macrophages and fibroblasts. Vessel lumen
remains narrowed or occluded
Intimal cell proliferation, capillary invasion
and recanalisation. Vessel again becomes patent.
Detachment
Thromboembolism

Question 8

Embolism

Answer 8

The transport of abnormal material (solid, liquid, gas)

by the blood stream and its impacting in a blood vessel

Question 9

Types of emboli

Answer 9

Thrombi
Fat
Gas
Tumour material
When tumour penetrates blood vessel parts may break away to form metastases.
Infective agents
Includes fragments of vegetations growing on heart valves in infective endocarditis.
Atheroma
Fragments of atheromatous plaque may break off
Amniotic fluid
uterus may force amniotic fluid and squames from infant into uterine veins of mother.
Foreign bodies
intravenous drug abuse
iatrogenic

Question 10

Gas emboli

Answer 10

Infusions
    Vascular surgery
    Caisson disease
    On ascending from the depths
     too rapidly, bubbles of N2 form
     in the blood stream and on
     entering the bones and joints
     cause the pain known as “the
     bends.”

Question 11

Shock

Answer 11

Shock is a physiological state characterized by a significant, systemic reduction in tissue perfusion, resulting in decreased tissue oxygen delivery and insufficient removal of cellular metabolic products, resulting in tissue injury

Question 12

Hypovolaemic shock

Answer 12

• haemorrhage – internal or external

severe burns

Question 13

Cardiogenic shock

Answer 13

large acute myocardial infarction

other acute cardiac disease

Question 14

Septic shock

Answer 14

endotoxins from Gram negative bacteria
exotoxins from Gram positive bacteria
both lead to dilation of blood vessels

Question 15

Anaphyllactic shock

Answer 15

severe form of allergic reaction

- food, antibiotics, insect stings

Question 16

Neurogenic shock

Answer 16

spinal cord trauma

regional anaesthesia

Question 17

Obstructive shock

Answer 17

cardiac tamponade
tension pneumothorax
massive pulmonary embolism

Question 18

Clinical features of shock

Answer 18

low systolic blood pressure: 90 beats/min
respiratory rate: 29 breaths/min
urine output: low
metabolic acidosis
hypoxia
cutaneous vasoconstriction or vasodilation
anxiety, agitation, indifference, lethargy, obtunded