DVT and PE Flashcards
What is a DVT?
Formation of thrombi within the lumen of the vessels making up the deep venous system - predominantly in venous valve pockets and other sites of presumed stasis
Types of DVT?
Distal Vein Thrombosis - DVT of the calves
Proximal Vein thrombosis - DVT of popliteal vein or of femoral vein (closer to the heart)
What is a PE?
Thromboemboli detach and travel through the right side of the heart to block lung vessels
Virchow’s triad and causes of 3 reasons?
Endothelial injury: Venous disorders Venous valvular disease Trauma/surgery In-dwelling catheters
Circulatory stasis: Left ventricular dysfunction Immobility or paralysis Venous insufficiency or varicose veins Venous obstruction from tumour, obesity or pregnancy
Hyper-coagulable states: Malignancy Pregnancy and peripartum periods Oestrogen therapy (HRT or contraceptive pill) Inflammatory Bowel Disease Sepsis Thrombophilia
Significance of Virchow’s triad?
All predispose to thrombus formation
Exposing risk factors for venous thrombo-embolic disease), i.e: acute conditions or previous happenings?
Surgery Trauma Acute medical illness Acute heart failure Acute resp failure Central venous catheterisation
Predisposing risk factors (patient characteristics)?
History of VTE (biggest risk of clot is having had one before) Chronic heart failure Advanced age Varicose veins Obesity Immobility or paresis Myeloproliferative disorders Pregnancy/peripartum period Inherited or acquired thrombophilia Hormone therapies Renal insufficiency
Inherited disorders that increase VTE risk?
Protein C or Protein S deficiency
Factor V Leiden mutation
Only increase risk by a small amount
Difference between provoked and unprovoked VTE?
Provoked VTE:
Transient/reversible factors, e.g: surgery or hospitalisation
Continuing/irreversible factors, e.g: cancer
Unprovoked (idiopathic) cause - no identifiable cause
Known consequences of VTE?
Fatal PE Risk of recurrent VTE Post-thrombotic syndrome (PTS) Chronic Thrombo-Embolic Pulmonary Hypertension (CTEPH) Reduced quality of life
What is post-thrombotic syndrome?
Chronic venous disease following DVT treatment
Valves no longer function so there is chronic pooling of blood
Also, valvular reflux leads to venous hypertension
Frequency of PTS?
Occurs in nearly 1/3rd of patients within 5 years after idiopathic DVT
Characteristic of PTS?
Pain Oedema Hyperpigmentation - iron deposition leads to staining of skin (hemosiderin deposition) Eczema Varicose collateral veins Venous ulceration
What is chronic thromboembolic pulmonary hypertension (CTEPH)?
Serious PE complication
Original embolic material is replaced with fibrous tissue into the intima and media of pulmonary arteries - pulmonary resistance and right-sided heart failure
Characteristics of CTEPH?
Initial phase - often asymptomatic
Followed by progressive dyspnoea and hypoxaemia
Investigations for DVT?
Pre-test probability scores:
D-dimer - reasonable test of exclusion (use with caution in patients with previous DVT)
Ultrasound - compressibility vs Doppler ultrasound
What is D-dimer?
Breakdown product of cross-linked fibrin
High -ve predictive value for VTE and low +ve predictive value for VTA
Uses of D-dimer?
Valuable first line screening test for suspected VTE with low Wells score
But non-specific (D-dimer is raised in many conditions)
Interpreting the Wells score?
If low probability, check D-dimer (if -ve, no imaging required)
Moderate/high probability - need imaging regardless of D-dimer (-ve imaging and +ve D-dimer requires repeat imaging)
What does Wells score indicate?
PE
What is Geneva score used for?
Low risk - if D-dimer is negative, may not need investigation
Intermediate risk - if D-dimer negative, consider stopping investigation (likely, need investigation to exclude)
High risk - regardless of D-dimer will need imaging
Other imaging techniques for PE?
CXR - usually normal in PE (can show pleural effusions and occasionally infarct)
V/Q scan - mismatched perfusion defects PE; still useful in small, peripheral PEs and pregnancy but is limited by frequency of inconclusive results
CTPA is “gold standard” (but no good for peripheral pulmonary vessels)
Pharmacological and mechanical interventions for DVT and PE?
Pharmacological interventions:
Anti-coagulation
Thrombolysis
Analgesia
Mechanical interventions:
Graduation compression stockings
IVC filters
Treatment of provoked VTE, to prevent recurrence?
Provoked VTA - LMWH for at least 5 days or until INR is greater than or equal to 2, for 24 hours (whichever is longer)
Vitamin-K antagonist (warfarin) within 24 hours and cont. for 3 months
Treatment of unprovoked VTE, to prevent recurrence?
LMWH for at least 5 days or until INR is greater than or equal to 2, for 24 hours
VKA within 24 hours and cont. for 3 months
Assess risks and benefits of cont. anticoagulation for prevention of VTE recurrence
Treatment of VTE in patients with active cancer, to prevent recurrence?
LMWH for 6 months
Reassess for continued treatment
Advantages of VKA?
Mainstay of long-term therapy
Can be used in those with severe renal impairment
Anti-coagulation can be reversed, using vit K
Disadvantages of VKA?
Slow onset/offset - requires bridging
Numerous INTERACTIONS with other drugs and foods
Narrow TI
Inter-individual variability in dose response
Need for INR monitoring
Advantages of Novel Oral Anti-Coagulants (direct)?
Predictable pharmacological profiles
Absence of major food and drug interactions
Do not require routine INR monitoring
May shift practice to longer treatment duration
Low bleeding risk and short half-life, so basic first aid could be used
Disadvantages of NOACs?
No available antidote
No readily available monitoring for special circumstances, e.g: major bleeding, urgent procedure
No long-term data
4 NOACs?
Apixaban
Rivaroxaban
Dabigatran
Edoxaban
Recommendations for Apixaban use?
Recommended as an option for treating and preventing DVT and PE in adults
Recommended as an option for prevention of VTE, in adults after elective hip/knee replacement surgery
Recommendations for Rivaroxaban use?
Option for treating DVT and preventing recurrence and PE, after a diagnosis of DVT in adults
Option for treating PE and preventing recurrence of DVT and PE in adults
Option for prevention of VTE in adults having elective total hip/knee replacement surgery
Recommendations for Dabigatran use?
Option for primary prevention of VTE inadults who have undergone total hip/knee replacement surgery
Option for treating and preventing DVT recurrence and PE in adults
Recommendations for Edoxaban use?
Option for treating and preventing recurrent DVT and PE in adults
Apixaban, Edoxaban, Rivaroxaban action compared to Dabigatran?
3 act on factor Xa
Dabigatran acts as a direct thrombin inhibitor
Comparison of VKA and rivaroxaban bleeding rates?
Rivaroxaban - significantly lower incidence of major bleeding compared with VKA in fragile patients (aged 75 years and up or those with moderate/severe renal impairment or patients with low body weight)
Why is drug use a special case?
Risk of haemorrhage/death vs embolic disease
Rivaroxaban vs fragmin use
Are they an active or retired injector? Injecting makes them pro-thrombotic
Which drug should be used in cancer?
Wight-adjusted FRAGMIN
What is phlegmasia?
Arterial compromise secondary to extensive DVT - so extensive that there is impaired arterial flow (limb ischaemia)
Recommendations for thrombolysis use in DVT?
Consider patients with symptomatic ileo-femoral DVT symptoms less than 14 days duration AND:
Goof functional status AND
A life expectancy of 1 year or more AND
A low risk of bleeding
Recommendations for thrombolysis use in PE?
Consider pharmacological systemic thrombolytic therapy for patients with PE and haemodynamic INSTABILITY (beneficial for those at high risk of deteriorating in hospital)
Do not offer pharmacological systemic thrombolytic therapy for PE and haemodynamic stabilty
Why are compression stockings used?
To prevent Post-Thrombotic Syndrome after DVT
How are compression stockings used?
To be worn as soon as possible after diagnosis
To be worn at least 2 years post-thrombosis on affected leg (s)
Must ensure there are no contraindications (individual risk analysis)
Major contraindication for compression stocking use?
Those with arterial disease
Only treatment for PTS?
Compression stockings
What are IVC filters?
Placed in IVC to catch clots
When are IVC filters used?
NOT ROUTINELY
Main use is temporarily peri-operatively
Temporary use in patients with proximal DVT or PE, who cannot have anti-coagulation treatment
Also, for patients with recurrent DVT or PE despite adequate anti-coagulation, only after considering increasing target INR or LMWH
IVC filters complications?
Thrombosis - not a replacement for anti-coagulation, ideally
