PBL 8 Flashcards
what is haemostasis?
a process to prevent and stop bleeding, meaning to keep blood within a damaged blood vessel (the opposite of haemostatis is haemorrhage)
what are some risk factors for DVT?
how can straining lead to DVT?
straining —> increased intrathoracic pressure
release —> lowered or normal pressure — leading to breaking of clots
PE cannot be ruled out if what are/is present?
- age >_ 50
- HR >_ 100
- SaO2 on room air <95%
- unilateral leg swelling
- hemoptysis
- recent trauma or surgery
- prior ER or DVT
describe a V/Q scan
- involves 2 isotopes
- isotopes are difficult to get
- gas used for ventilation is very rarely available
- have moved away from V/Q scan
describe a CTPA
- Computerised Tomography Pulmonary Angiogram
- more readily available - isotope not needed
- can also see tumour + PE
- exposes patient to more radiation
V/Q scans and CTPA both use what?
injected radioactive material
what are all heparins made from?
pork
what is VTE?
= venous thromboembolism
= when DVT and PE occur together
symptoms of DVT
- swelling in affected leg
- pain in leg
- red or discoloured leg
- symptoms of PE
symptoms of PE
- SOB
- pleuritic chest pain (worse on inspiration)
- feeling dizzy or fainting
- tachycardia
- dyspnoea
- haemoptysis
- low BP
how does a PE cause right sided HF and a decrease in BP?
pulmonary embolism —> increase pulmonary vascular pressure —> increase RV pressure —> right-sided HF —> decrease SV —> decrease CO —> decrease BP
what is chronic venous insufficiency?
when leg veins don’t allow blood to flow back up to your heart. causes leg and foot swelling, varicose veins and aching legs. can be due to faulty valves inside veins. can be due to DVT
what do intact blood vessels release?
- prostacyclin (PGI2) is secreted to inhibit platelet activation
- nitric oxide is secreted to inhibit platelet aggregation
extrinsic vs intrinsic pathways
extrinsic
- quicker to respond and more direct
- begins when damage occurs to the surrounding tissues
- extrinsic tenase complex leads to activation of X, which activates the common pathway
- events completed within a few seconds
intrinsic:
- longer and more complex
- factors involved are intrinsic (present within) the bloodstream
- events completed within a few minutes
definition of obesity
BMI > 30 (>25 is overweight)
why is obesity a risk factor for DVT?
> obesity promotes chronic inflammation and impaired fibrinolysis (enzymatic breakdown of fibrin in a blood clot) — both lead to an increased risk of thrombosis
obesity leads to overproduction of plasminogen activator inhibitor-1 that comes from adipocytes or fat cells) — both lead to an increased risk of thrombosis
obesity leads to overproduction of plasminogen activator inhibitor-1 that comes from adipocytes or hepatocytes — leads to inhibition of clot break down or fibrinolysis promoting clot formation
more adipokines released from adipose tissue — activate platelets
name other risk factors for DVT
- major surgery
- compression
- pregnancy
- increasing age
- obesity
- malignancy
- long distance flight
- bed rest/hospitalisation
- genetics eg. antithrombin III deficiency (autosomal dominant) (antithrombin inactivates Xa and
thrombin)