L11 Causes, Prevention & Consequences of DVT/VTE

Question 1

thrombosis

Answer 1

formation of a blood clot within the circulation

Question 2

thrombus

Answer 2

blood clot formed in an intact blood vessel or chamber and fixed at that site

Question 3

Thrombosis-emoblus

Answer 3

blood clot breaking free leading to occlusion elsewhere in the circulation

Question 4

virchows triad

Answer 4

• Vessel wall abnormality – endothelial damage ( sepsis, toxins) or compression ( oedema and trauma)
• Increased coagulability – thrombophilia ( congenital – protein c deficiency or factor V Leiden) ( acquired – pregnancy , hyper viscosity eg polycythaema , anti-phospholipid syndrome , malignancy)
• Venous stasis ( global – low CO , local – impaired muscle pumping( venous return for veins , venous return depend on venous valves and muscle pumps, proximal occlusion , turbulence

Question 5

what things promote platelet aggregation ( via glycoprotein 2b/3a)

Answer 5

fibrinogen and vWF

Question 6

what things prevent clot propagation

Answer 6

PGI2 and NO from adjacent undamaged endothelium prevent platelet adhesion

Question 7

the process of a clot being removed is by the process of fibrinolysis. How does this process work

Answer 7

plasminogen that is already incorporated in the clot is converted to plasmin by tpa(released slowly from the damaged endothelium) and urokinase. The plasmin then causes fibrin to be converted into FDPs - fibrin degradation products

Question 8

what are anti-platelets used for

Answer 8

mainly for prevention of arterial platelet aggregation ( coronary ,carotid, cerebral )

Question 9

what does heparin do

Answer 9

converts anti-thrombin to its highly active form - used in acute management of dot/pe

Question 10

LMWH predominately activates anti-thrombin inhitbing factor 10
where does unfractionated heparin predominately act

Answer 10

on ant-thombin inhibiting thrombin

Question 11

which heparin is reversible with protamine

Answer 11

unfractionated heparin

Question 12

DOAC thrombin inhibitors

Answer 12

dabigatran

Question 13

DOAC Xa antagonists

Answer 13

Rivaroxaban

apixaban

Question 14

what is bridging therapy

Answer 14

stopping warfarin 5 days before surgery - if patient at risk start prophylactic treatment - 12 24 hours prior to surgical procedure.

Question 15

presentation of DVT

Answer 15

pan 
swollen 
red
worse on dorsiflexion 
tenderness thigh or calf 
oedema unilateral 
venous engorgment - red to purple and warm

Question 16

D-dimer is an FDP that can be messaged. it is a very sensitive marker for VT but not specific what does it vary with

Answer 16

age, pregnancy and raised haemorrhage , trauma, surgery, sepsis etc

Question 17

what would a DVT show on blood gas

Answer 17

hypoxia - low O2 due to V/Q mismatch and hypocarbia as uncertain respiratory stimulus

Question 18

gold standard for PE

Answer 18

CTPA