Lecture 6 - Clinical Considerations in VTE Flashcards
What is VTE?
Undesirable blood clotting in the venous system
Define Deep Vein Thrombosis (DVT)
Usually deep vein in the leg
When fragments of a clot break away, enter arterial circle elation form a secondary embolus elsewhere such as?
Pulmonary Artery - Pulmonary Embolism
Cerebral Artery - Stroke/ Transient Ischaemic Attack (TIA)
What are the symptoms of VT?
Usually unilateral
Swollen, tender leg
Heavy ache in the affected areas
Warm erythematous (red) skin
Pitting oedema
Prominent superficial veins
What level WELLS SCORE is likely of DVT?
more than 2 DVT likely
less than 2 DVT unlikely
Symptoms of PE
May be symptomless
Concurrent DVT
Breathlessness
Cough - dry/ blood stained (haemoptysis)
Pleuritic chest pain/ upper back pain
Tachycardia (fast heart rate)
Tachypnoea (fast respiratory rate)
Hypotension
Syncope (fainting)
Hypoxia/ cyanosis (turning blue)
What WELLS SCORE is likely of PE?
more than 4 PE likely
less than 4 PE unlikely
What are the investigations for VTE?
D-dimer
Venous Ultrasound ‘Doppier Scan’
CT Pulmonary Angiography (CTPA)
Ventilation Perfusion (VQ) Scan
Define d-dimer
By-product formed when thrombus (such as that found in DVT or PE) is degraded naturally by the body
Positive levels in the blood suggest DVT/PE
Define Ventilation Perfusion (VQ) Scan
Uses radiopharmaceutical material to visualise the lungs, useful in confirming PE
Define Venous Ultrasound ‘Doppier Scan’
An imaging technique used to visualise venous blood clots in situ
Useful in confirming DVT
Define CT Pulmonary Angiography (CTPA)
An imaging technique used to visualise thrombus in the pulmonary arteries
Useful in confirming PE
What are the bleeding risk factors?
Surgery related - neurosurgery, spinal and eye
Lumbar puncture, epidural, spinal anaesthesia
Medical conditions - recent stroke, impaired liver function, bleeding disorders, hypertension, thrombocytopenia (low platelets)
Medicine - anti-coagulants
What are the clotting risk factors?
Stagnation of blood - not mobile
Vascular injury - surgery, broken bones, vasculitis, varicose veins
Medical conditions - pregnancy, clotting disorders, previous/family history, some cancers and chemotherapies, CV or lung disease, inflammatory disease, COVID-19
Others - age >60, overweight, smoking, oestrogens (HRT/COC), dehydration
When should patients have a VTE Risk assessment?
Hospitalised patients should have their clotting vs bleeding risk assessed on admission to the hospital and after every change in clinical condition
If clotting risk>bleeding risk need VTE prophylaxis with an anti-coagulant to prevent VTE from developing
Examples of Low Molecular Weight Heparin (LMWH)
Dalteparin, enoxaparin, tinzaparin
Given by sc fixed dose injections on the basis of body weight
Predominately really excreted
What can be taken when bleeding occurs on a LMWH?
Antidote - protamine (partial reversal only)
What are the main uses of LMWH?
VTE prophylaxis
Treatment of confined VTE - prevents enlargement of clots, enabling clot breakdown by the body own homeostatic mechanisms
Anti-coagulant ‘bridging’
What monitoring is required with LMWHs?
Signs of bleeding
LFTS
Platelets
Potassium
What are the cautions with LMWHs?
Proven or suspected bleeding
Thrombocytopaenia (low platelets)
Certain conditions e.g. stroke in the last 14 days
CNS or eye surgery, trauma, anaesthesia
Poor renal function
What are unfractionated heparins (UFH)?
Larger polymer chains than LMWH
Eliminated by the reticuloendothelial system with low level of renal clearance
What can be taken when bleeding occurs on a UFH?
Antidote- protamine (complete reversall)
What are the main uses of UFH?
VTE prophylaxis if LMWH is unsuitable
Subcutaneous, fixed-dose, bolus-injection up to three times a day
Treatment of confirmed DVT/PE if LMWH is unsuitable - initial intravenous loading dose then continuous intravenous infusion, titrated to achieve a target aPTT ratio
What are the cautions with UFH?
As for LMWH
Continuous monitoring of the aPTT ratio if treating confirmed DVT/PE
Define the Recombinant Tissue Plasminogen Activator (r-tPA)
Converts plasminogen to plasmin to actively degrade clots
Normally given as an initial intravenous loading dose followed by a one-off intravenous dose when massive PE suspected
When is Recombinant Tissue Plasminogen Activator (r-tPA) taken?
Reserved for use in the treatment of ‘massive’ PE only:
- severe hypotension
- cardiorespiratory arrest
no role in VTE prophylaxis or treatment of DVT
When are vitamin K antagonists used?
Treatment and secondary prevention of DVT/PE
Prevention of thrombus formation on prosthetic heart valves or after mitral valve surgery
Stroke prevention in AF
Example of a vitamin K antagonist
Warfarin
Cautions in warfarin
Bleeding, haemorrhage stroke
within 72 hours of surgery with high bleed risk e.g. polypectomy
Pregnancy (teratogenic)
Warfarin has many interactions with food and other drugs
What monitoring is required with Warfarin?
Platelets, LFTs, signs of bleeding, INR
Define INR
Measure the degree of anti-coagulation conferred by vitamin K antagonists only
Measured by regular finger prick blood tests approx monthly Warfarin dose is titrated to achieve a ‘target INR’
What is the target INR?
2-3 - balance of benefits and risks
What is the yellow book?
issued to all patients nearly starting Warfarin
Details their latest INR reading and their current warfarin dose
Community pharmacists must check the patients Yellow Book when issuing warfarin
Examples of warfarin loading
High doses during the first days of treatment to establish therapeutic INR
Thereafter the dose is adjusted to maintain therapeutic INR
Key counselling points for warfarin
Compliance - advice to take at the same time everyday
Reason for taking warfarin - decreases your blood to clot
Explain obtaining a supply
Need for regular monitoring of INR
Effects of poor anti-coagulant control
Action to take if bleeding or bruising occur - check INR
Appropriate action if patient can’t take warfarin - e.g. vomiting or diarrhoea
Starting, stopping and changing the dose of warfarin
Drug/ food interactions - foods high in vitamin K
Alcohol intake - moderation
Contraception, HRT and pregnancy
Surgical procedures e.g. warfarin
Dental procedures - need to tell dentist you are on warfarin
Examples of DOACs
Rivaroxaban, apixaban, edoxaban, dabigatran
What are the main uses of DOACs?
Extended VTE prophylaxis
Treatment and secondary prevention of DVT/PE - usually 3-6 months after first VTE
Stroke prevention in non-valvular atrial fibrillation (AF) - lifelong duration or until sinus rhythm is restored
When are Elasticated Graduated Compression Stockings used?
VTE prophylaxis of pharmacological prophylaxis can’t be used
May be used in addition to pharmacological VTE prophylaxis if high clot risk
Symptomatic relief of confirmed DVT - no role in active treatment of DVT
When is antiembolism stockings not recommended?
Allergy to the material
Abnormal leg shape
Skin fragile/ in poor condition
Heart Failure
Peripheral/ sensory neuropathy
Acute stroke
What is Intermittent Pneumatic Compression (IPC) (Flowtrons)?
Thigh/knee-length pads that fit around the leg
Continuously inflate and deflate by means of a battery-powered pump
Designed to mimic walking
Increase volume and rate of blood flow
Main uses of Flowtrons
VTE prophylaxis if pharmacological prophylaxis can’t be used or is unsuitable
Can be used in addition to pharmacological treatment if the clot risk is high
Alternative to compression stockings
Useful after acute stroke as compression stockings can’t be used
Define a geek device
Low level of stimulation to the common perineal nerve, activating the calf and foot muscle pumps to promote blood flow
Main uses of geko device
VTE prophylaxis when other pharmacological and mechanical forms can’t be used
Define Inferior Vena Cava (IVC) filter
Wire meshwork temporarily fitted to the lumen of the inferior vena cava to prevent clots from entering the right atrium
Main uses of IVC filter
Confirmed DVT/PE in patients who are already fully pharmacologically anticoagulated or patients who can’t receive pharmacological treatment
VTE prophylaxis in patients at high risk of VTE who cannot receive pharmacological treatment
Define catheter-directed thrombolysis
Treat extensive, symptomatic DVT/PE that has not responded to conventional anticoagulant treatment
Catheter inserted through venous system and fed directly into the clot
Thrombolytic drugs released from the catheter to dissolve the clot in situ
Define percutaneous mechanical thrombectomy
To treat extensive symptomatic DVT/PE that has not responded to conventional anticoagulant treatment or catheter-directed thrombolysis
A catheter inserted through venous system and fed directly into the clot
Clot is broken up by catheter attachment and removed
Thrombolytic drugs can be used to assist in breaking the thrombus down
