VTE Flashcards
(44 cards)
1
Q
When should a VTE assessment be carried out
A
- be carried out on admission to hospital for all patients above 16 years old
- ## should then be repeated 24 hours after admission or with change or condition
2
Q
What are the major VTE risk factors
A
- Cancer -r isa of VTE is 4x higher in cancer patients than in the general population
- significant immobility - compared to normal activity, due to bed rest (>5 days) or hospitalisation, bed rest accounts for 28% of cases of confirmed PE
- pregnancy - the risk of antenatal VTE is 4-5x higher in pregnant women than in non pregnant women of the same age
- previous VTE - 30% of patients with a previous VTE have a recurrence in the next 10 years
3
Q
What are the major VTE risk factors
A
- Cancer - risk of VTE is 4x higher in cancer patients than in the general population
- significant immobility - compared to normal activity, due to bed rest (>5 days) or hospitalisation, bed rest accounts for 28% of cases of confirmed PE
- pregnancy - the risk of antenatal VTE is 4-5x higher in pregnant women than in non pregnant women of the same age
- previous VTE - 30% of patients with a previous VTE have a recurrence in the next 10 years
4
Q
Name some examples of low molecular weight heparin
A
- enoxaparin
- dalteparin
- tinzaparin
5
Q
How does low molecular heparin work
A
- LMWH binds to antithrombin
- this inhibits activated factor X and therefore reduces the conversion of prothrombin to thrombin
6
Q
How is LWMH given
A
- given subcutaneously for VTE prophylaxis as a fixed dose
7
Q
how can LWMH be reduced
A
- protamine sulphate
8
Q
what are the risks of LMWH
A
- heparin induced thrombocytopenia (HIT)
- osteoporosis
9
Q
what is the difference between LMWH and unfractionated heparin
A
- unfractionated heparin has a higher molecular weight compared to LMWH
10
Q
How does unfractionate heparin work
A
- UFH binds to antithrombin to inactivate factor Xa and prevent the conversion of prothrombin to thrombin
11
Q
What reverses unfractionate heparin
A
- reversed by protamine sulphate
12
Q
How does fondaparinux work
A
- fondaparinux is a synthetic drug which binds with antithrombin to enhance factor Xa inhibition
13
Q
Name some DOCAs
A
- rivaroxaban
- dabigatran
- apixaban
14
Q
How do apixaban and rivaroxaban work
A
- these are oral selective direct factor Xa inhibitors - rivaroxaban can be used for prophylaxis in adults having hip or knee replacement surgery
- apixaban can be used post hip or knee surgery
15
Q
how does dabigatran work
A
- dabigatran is converted to the active dabigatran by hydrolysis
- it is a direct thrombin inhibitor
16
Q
How is APPT affected by VTE prophylaxis
- Heparin
A
- heparin can prolong APPT time
- dabigatran can prolong APPT but it does not coordinate with the concentration of dabigatran
17
Q
How is prothrombin affected by VTE prophylaxis
A
- Rivaroxaban can prolong PT/INR
18
Q
What does PT measure
A
- extrinsic and common coagulation pathway
19
Q
What does APPT measure
A
intrinsic and common coagulation pathway
20
Q
What does thrombin time measure
A
- measures the conversion of fibrinogen to firkin by the action of thrombin
21
Q
What prolongs the thrombin time
A
- Dabigatran and heparin
22
Q
What is Anti-FXa used to measure
A
- this can be used to measure the activity of heparin or the factor Xa inhibitors int he plasma
23
Q
What is the downside of Anti-FXa
A
- difficult to interpret in obese, malnourished and pregnant patients
24
Q
What should be avoided for VTE prophylaxis
A
- apixaban, ribaroxaban - should be avoided if creatinine clearance is <15 mL/min
- a dose reduction may be required if the creatinine clearance is <50mL/min
- dabigatran - should be avoided if the creatinine clearance is <30 mL/min, a dose reduction may be required if the creatinine clearance is < 50mL/min
25
What should be avoided for VTE prophylaxis in kidney damage
- apixaban, ribaroxaban - should be avoided if creatinine clearance is <15 mL/min
- a dose reduction may be required if the creatinine clearance is <50mL/min
- dabigatran - should be avoided if the creatinine clearance is <30 mL/min, a dose reduction may be required if the creatinine clearance is < 50mL/min
26
How do anti-embolic stockings work
- compress the muscles in the calves to improve venous return
- they are fitted to size
- should be placed below the knees to promote maximal calf compression
27
How to intermittent pneumatic compression device work (IPC)
- an air pump inflates and deflates the sleeves to improve venous return in the lower limb
- mimicking the natural venous return when the leg muscles contract
- used for immobile patients
28
Who should not have anti embolism stockings
- severe leg oedema
- allergy to material
- suspected or proven peripheral arterial disease
- peripheral arterial bypass grafting
- peripheral neuropathy or other causes of sensory impairment
- any conditions where stockings may cause damage such as fragile skin or dermatitis
- major limb deformity or unusual leg size or shape preventing correct fit
29
describe when VTE stockings can be used
- should be worn day and night until a patient has no longer reduced mobility
- removed daily to check skin integrity
- may not be suitable for all patients
- can be given to pregnant women
30
What should you check pre prescription for VTE prophylaxis
- patients weight
- full blood count
- clotting screen
- kidney function
- liver function
31
what are the absolute contraindications to VTE prophylaxis
- active bleeding
- hypersensitivity to the drug
- newly diagnosed heparin induced thrombocytopenia
32
What are the relative contraindications to VTE prophylaxis
- known bleeding disorder
- platelets < 50x109/L
- peptic ulcer disease and/or oesophageal varices
- Severe hypertension
- Severe renal failure
- recent cerebral haemorrhage
- coagulopathy
- major trauma or recent neurosurgery or eye surgery
- past history of HIT
- spinal or epidural anaesthesia
33
describe what makes up a wells score
- clinical signs and symptoms of a DVT = 3
- an alternate diagnosis is less likely than PE = 3
- heart rate >100 beats per minute = 1.5
- heart rate is >100bpm = 1.5
- immobilisation for more than 3 days or surgery in the previous 4 weeks = 1.5
- previous DVT/PE = 1.5
- Haemoptysis = 1
- malignancy (on treatment, treated in the last 6 months or palliative) = 1
34
What does the wells score have to be higher than in order to cause a PE
- if greater than 4 = PE likely
| - if less than 4 = PE unlikely
35
What do you do if a PE is unlikely
D dimer
- if D dimer negative consider an alternative diagnosis
- If D dimer positive consider a CPTA
36
What do you do if a PE is likely
- Immediate CTPA
37
What do you do if a CTPA cannot be performed
- interim LMWH whilst waiting for one
| - might be a state dose or written regular if there is a longer delay
38
What can be found on an ECG with a PE
- Sinus tachycardia
- right ventricular strain pattens - T wave inversion in V1-V4 and inferior leads
- right bundle branch block
- right axis deviation
- S1Q1T3 pattern - Deep S wave in lead 1, Q wave in III, and inverted T wave in III - sign of acute cor pulmonale
39
What is an embolus
- an embolus is any intravascular material that has migrated from its original location to block another vessel
40
What is Virchow's triad
- three factors that can lead to thrombus formation
41
What makes up Virchow's triad
- venous stasis
- trauma
- hypercoagulability
42
What is an unstable PE
- hypotensive (systolic blood pressure <90mmHg)
- have a drop in the SBP of 40mmhg from baseline for 15 minutes
- require inotropes for management of their hypotension
43
how should an unstable PE be measured
- thrombolysis
44
name the types of thrombolysis used in an unstable PE
- surgical embolectomy
- catheter directed Treatment
- venous filter
