6. Venous Thromboembolism aka VTE (DVT and PE) Flashcards
what does DVT mean
deep vein thrombosis
what does PE mean
pulmonary embolism
what are both DVT and PE forms of
VTE - venous thromboembolism
what is a thrombus
a blood clot within the body
what is an embolus
material which is transported in the blood stream and lodges in a blood vessel at a different site
where do most VTE develop and why
in the deep veins of the leg
what disease makes VTE more likely
varicose veins
what 3 things make up the Virchow’s triad
stasis of blood flow
endothelial injury
hyper-coagulability
give some reasons why patients may have the following elements of the virchows triad
- stasis of blood flow
- endothelial injury
- hyper-coagulability
- they are immobile ie in bed
- acute phase reactant proteins (that increase due to inflammation) like fibrinogen, factor VIII and vWF
- obvious is there is a leg or pelvic injury or if need plaster cast. not that stasis itself will cause some endothelial injury
What mechanical interventions can prevent VTE
anti-embolism stockings (AES)
intermittent pneumatic compression sleeves (IPC)
name 3 pharmacological interventions that can prevent VTE
low lose low molecular weight heparin (SC) - LMWH
low dose unfractionated heparin (IV) - UFH
direct anti-Xa and anti-thrombin drugs (O)- DOAC
what negative effect could you get form heparin therapy
herpain induced thrombocytopenia and thrombosis (HITT)
in the prevention of VTE why would you not use warfarin
the intensity of anticoagulation is less predictable and erratic and bleeding risk is much high than that with heparin or DOAC
investigation before treatment should only be done in what time frame for
- PE
- DVT
if investigation can be done within 1 hour for PE or 4 hours for DVT
particularly post-op why is it preferred to use UFH (un fractionated heparin)
can be immediately reversed (protamine sulphate) or just stopped if post-op bleeding or redo surgery is required
why does heparin need to be continued when starting oral warfarin
it can take 48-72 hours to reach its therapeutic range and at that point, heparin can be stopped
Name some risk factors for VTE
immobility recent surgery long haul flight s pregnancy hormone replacement therapy with oestrogen (combined oral contraceptive pill and hormone replacement therapy) malignancy polycythaemia systemic lupus erythematosus thrombophiila
what condition can predispose patients to developing blood clots
antiphospholipid syndrome
what is the main contraindication for compression stockings
peripheral arterial disease
What is the usual presentation of a DVT
almost always unilateral
- calf or leg swelling
- dilated superficial veins
- tenderness to the calf (particularly over the site of the deep veins
- odema
- colour changes to the leg
how do you examine for leg swelling
measure the circumference of the calf about 10cm below the trivial tuberosity
more than 3cm difference between the calves is significant
what score predicts the risk of a patient presenting. with symptoms actually having a DVT or PE
the Wells score
what single blood test can differentiate between a patients having VTE or not
d-dimer
can exclude VTE where there is a low suspicion
as well as being raised in VTE, what other conditions cause a raised d-dimer
pneumonia malignancy heart failure surgery pregnancy
what investigation can diagnose a DVT
ultrasound doppler of the leg and positive d-dimer
how can a PE be diagnosed
CT pulmonary angiogram (CTPA)
ventilation perfusion scan (VQ) scan
what is the initial management of a VTE and when should it be started
treatment dose low molecular weight heparin (LMWH)
should be started immediately before confirming the diagnosis in patients where DVT or PE is suspected and there is a delay in scan
give some common examples of LMWH
enoxaparin
dalteparin
tinzaparin
what are the options for switching to long term anticoagulation in VTE
warfarin
NOAC
LMWH
What is the target INR for warfarin and what does a raised INR mean
2-3
means blood is taking longer to clot outside your body
what is the long term preferred 1st line anticoag for pregnancy or cancer
LMWH
How long should anticoagulation be continued for;
- if there is an obvious reversible case
- if the cause is unclear, there is recurrent VTE or there is an irreversible underlying cause such as thrombophiliia
- in active cancer
- 3 months
- beyond 3 months (usually 6 in practice)
- 6 months
if patients have their first VTE without a clear cause then NICE recommend to screen for cancer
Q: how do you do this
- history and examination
- CXR
- bloods ( FBC, calcium and LFT)
- urine dipstick
- CT AP in pt over 40
- mammogram in women over 40
if patients have their first VTE without a clear cause then what else do you want to test for apart from cancer screening
antiphospholipid syndrome
- check this by checking for antiphospholipid antibodies
What is budd-chiari syndrome and how does it classically present
a blot clot (thrombosis) develops in the hepatic vein blocking the outflow of blood
- associated with hyper-coagulable states and causes acute hepatitis
- abdo pain, hepatomegaly and ascites
Describe the flow of a blood clot to the lungs
from blood vessel in the body, to the right atrium, passes out of the right ventricle and into the pulmonary arteries where it lodges
what are the physical signs of PE
increased RR
tachyarrhythmias (comment is sinus tachycardia but may have atrial fibrillation)
possibly signs of DVT
what is a massive PE
large clot that lodges in the right side of the heart or in both pulmonary arteries (saddle embolus)
how does a massive PE classically present
syncope (LOC) as well as the other symptoms of PE
- increased RR
- tachyarrhythmias
- signs of DVT
how is massive PE clinically defined
the presence of arterial hypotension (systolic BP less than 100) or cariogenic shock/cardiac arrest
- medical emergency and requires urgent thrombolysis
What are the risk factors for DVT
- active cancer (includes treatment within the past 6 months)
- FH of DVT
- immobility for 3 days or more, or major surgery within 12 weeks
- Age especially over 60s
- previous DVT
- note that it is not related to gender
What is PERC and how is it used
Pulmonary embolism rule out criteria score
- 8 clinical criteria
Investigating PE:
why would you wan to do a FBC
useful prior to anticoagulation and to rule out infection
Investigating PE:
why would you wan to do a LFT
to check before starting anti-coat therapy
Investigating PE:
why would you wan to do an ECG
to asses the rhythm in any tachycardia patient
on and ECG what are you looking for which would suggest the patient has a massive PE
In big PE, may show signs of R heart strain (S wave in I, Q waves in III, T waves in III)
What is the investigation of choice in most people with a high probability of PE, or low probability and raised D-dimer
CTPA and if not pregnant then a V/Q scan
in what scenario would you want to do a CRP
if an infection is indicated
as well as LFT what other blood test would you want before starting on anti-coag treatment
U and E
How would you exclude a pneumothorax
CXR
how would you investigate for a massive PE with haemodynamic compromise to look for RHF
echocardiogram
true or false;
- a d-dimer is indicated before a CTPA if someone has a high probability of PE
false
should do CTPA first if there is a high suspicion
what can be safely excluded if D-dimer result is negative
VTE, PE and DVT
in someone with PE they may get type 1 respiratory failure. What is this
low oxygen and normal CO2
- there is a V/Q mismatch as parts of her lung are getting air into them, but have no blood flow for gas exchange as they have PE
in patients with PE why would they have respiratory alkalosis
high RR so they are blowing off her CO2
Give some examples of LMWH and give the option to patients that have personal, religious or cultural preference s
most LMWH are made of porcine
dalteparin and enoxaparin are the main two
Fondaparinux is the synthetic alternative
name some common DOAC
Apixaban rivaroxaban ( other examples are dabigatran and edoxaban)
in which patients. would DOAC be contraindicated in
severe renal or hectic impairment or if there is a view to starting warfarin
what are the common effects of DOAC
bleeding, bruising, nausea and anaemia
in what specific scenarios is rivaroxaban contraindicated
if you are pregnant
hepatic impairment
renal disease is eGFR of less than 15 (warfarin would be safer if less than 30)
What is the first line treatment for PE
Apixaban or rivaroxaban
if Apixaban or rivaroxaban aren’t suitable then LMWH for at least 5 days followed by what drug
dabigatran or edoxaban
Name some common respiratory causes that can cause similar symptoms to a PE
pneumothorax
Pneumonia
Acute bronchitis
acute. exacerbation of asthma
name some common cardiac cause that can cause similar symptoms to a PE
ACS
congestive heart failure
pericarditis
unstable angina
Name some other differentials that can cause similar symptoms to a PE
musculoskeletal chest pain GORD vasovagal syncope postural hypotension panic disorder
