3-DVT and PE Flashcards
what is the DVT?
A thrombosis of the deep veins of the extremities that can lead to pulmonary embolism. Clinical signs of DVT include swelling, tenderness, and redness or discoloration. Risk factors include the Virchow triad: endothelial damage (surgery/intravascular instrumentation), venous stasis (immobilization, obesity), hypercoagulable state (undetected malignancy, thrombophilia).
what is PE?
an obstruction of the pulmonary artery and/or one of its branches by a thrombus that primarily arises from the deep vein system in the legs or pelvis and embolizes to the lungs via the inferior vena cava. Less commonly, the cause of obstruction is a fat or air embolus. Risk factors include stasis (e.g., immobility, surgery), hypercoagulable states (e.g., pregnancy and the puerperium), and endothelial dysfunction (e.g., trauma)
DVT most commonly involves what vein?
calf veins
DVT occurs in up to half of patients who:
- suffer major trauma (+ long periods of immobilization)
- suffer femoral and tibial fractures
- undergo major general surgical/orthopaedic procedures
what are the risk factors of DVT
- -History of DVT or PE (30x increased risk) [1]
- -Immobilization: e.g., post-surgery, long-distance flights, –trauma (20x increased risk)
- -Age > 60 years
- -Malignancy
- -Hereditary thrombophilia (especially factor V Leiden)
- -Pregnancy, estrogen use (oral contraceptives)
- -Obesity
- -Smoking
- -IV drug use
- -Nephrotic syndrome
- -Insufficient thrombosis prophylaxis, noncompliance with prophylaxis
what cancers particularly are associated with increased risk of VT?
Gastric, pancreatic, pulmonary, gynecological, and urological tumors are particularly associated with an increased risk for DVT because these types of tumors produce proteins and cytokines with thrombophilic effects.
what is the pathophysiology of DVT
- -The Virchow triad refers to the three main pathophysiological components of thrombus formation.
1) Hypercoagulability: increased platelet adhesion, increased clotting tendency (thrombophilia)
2) Endothelial damage: inflammatory, traumatic
3) Venous stasis: varicosis, external pressure on the extremity, immobilization, local application of heat
what is the classification of risk of developing DVT in post-surgery patients?
1) LOW
- -Age < 40
- -Surgery < 30minutes
- -Rapid postoperative mobilization
- -No major risk factors
2) MEDIUM
- -age>40
- -Abdominal surgery under GA
- -Moderate obesity
- -One major risk factor
3) HIGH
- -Age > 50
- -Pelvic surgery or trauma
- -Prolonged postoperative immobilization
what are the clinical features of DVT?
- -Swelling
- -Erythema
- -Pain
- -Tenderness
- -Homan’s sign
- -fever
what is the Homan sign?
calf pain on dorsal flexion of the foot
why DVT is more common in the left lower extremity
Due to compression of the left iliac vein by the overlying right iliac artery
what is the May-Thurner syndrome?
compression of the left iliac vein between the right iliac artery and a lumbar vertebral spur (occurs in > 20% of adults)
Affected individuals may be asymptomatic or present with left iliofemoral venous thrombosis.
what are the DVT investigations?
• Serum D-dimer levels • Byproduct of fibrin cross- linkage • Sensitive but not specific • Duplex ultrasonography - Investigation of choice • Contrast venography - Now less commonly used
what is the investigation of choice in DVT
duplex USG
what is the role of D-dimer testing in DVT?
- -High sensitivity (∼ 95%), low specificity (∼ 50%)
- -Useful for ruling out DVT (normal D-dimer levels rule out DVT)
- -Elevated D-dimers alone are not proof of DVT.
what is the role of Doppler USG in DVT?
- -A combination of ultrasonography (to visualize the vein) and Doppler (to assess blood flow abnormalities) in which the examiner applies gentle pressure to normally compressible veins using an ultrasound probe
- -High sensitivity and specificity in the popliteal and femoral veins, but very operator dependent
- -Indications: clinical suspicion of a DVT or pulmonary embolism
- -Findings: noncompressibility of the obstructed vein, visible hyperechoic mass, absent or abnormal flow in Doppler imaging
what are the classical symptoms of PE?
- dyspnoea
- pleuritic chest pain
- haemoptysis
what are the non-specific signs of PE?
- tachycardia
- fever
- tachypnoea
- pleural rub or effusion (later)
what are the clinical features of PE?
- -Acute onset of symptoms, often triggered by a specific event (e.g., on rising in the morning, sudden physical strain/exercise)
- -Dyspnea and tachypnea (> 50% of cases)
- -Sudden chest pain (∼ 50% of cases), worse with inspiration
- -Cough and hemoptysis
- -Possibly decreased breath sounds, dullness on percussion, split-second heart sound audible in some cases
- -Tachycardia (∼ 25% of cases), hypotension
- -Jugular venous distension (Right ventricular pressure overload.)
- -Low-grade fever
- -Syncope and shock with the circulatory collapse in massive PE (e.g., due to a saddle thrombus)
- -Symptoms of DVT: unilaterally painful leg swelling
what investigations are used for PE?
1)CXR: loss of vascular markings or wedge shaped consolidation 2)Arterial Blood Gas Arterial blood gas may show reduced oxygen partial pressure with low oxygen saturation indicating hypoxia. 3)ECG 10-20% of patients will show: • prominent P waves • ST-segment depression • T-wave inversion in leads III, aVF, V1, V2, V3 4) ventilation/perfusion scintigraphy 5)CT angiography
what is the definitive diagnosis of PE
CT angiography
what is the role of D-dimer in PE?
- -In patients with a low or medium probability of PE (Wells score ≤ 4) → measure D-dimer levels (+ ABG evaluation + CXR)
- -If positive (D-dimers ≥ 500 ng/mL) → CTA → evidence/exclusion of PE
- -If negative → PE unlikely → consider other causes of symptoms
what is the Wells criteria of PE?
–Clinical symptoms of DVT -3
–PE more likely than other diagnoses-3
–Previous PE/DVT-1.5
–Tachycardia (heart rate > 100/min)-1.5
–Surgery or immobilization in the past four weeks-1.5
–Hemoptysis-1
–Malignancy (being treated, in palliative care or –diagnosis less than 6 months ago)-1
—Wells criteria (clinical probability)
Total score of 0–1: low probability of PE (∼ 10%)
Total score of 2–6: moderate probability of PE (∼ 30%)
Total score of > 6: high probability of PE (∼ 65%)
what are the findings of CTA of a patient with PE?
- -Helical spiral CT/CT pulmonary angiography (CTPA): —-best definitive diagnostic test
- -Contrast-enhanced imaging of the pulmonary arteries
- -High sensitivity, specificity and immediate evidence of pulmonary arterial obstruction
- -Visible intraluminal filling defects of pulmonary arteries
- -Wedge-shaped infarction with pleural effusion is almost pathognomonic for PE
what is the role of ventilation/perfusion scintigraphy in PE?
–Indication: an alternative to CT angiography in patients with severe renal insufficiency or contrast allergy
–Method: detects areas of ventilation/perfusion (V/Q) mismatch via perfusion and ventilation scintigraphy
Assessment
–Perfusion failure in the normally ventilated affected pulmonary area (mismatch) suggests PE
–Evidence of normal lung perfusion rules out PE → ventilation scintigraphy superfluous
what are the general features of PE management?
- -45° reclining sitting posture
- -Oxygen supplementation and intubation if respiratory failure
- -IV fluids and/or vasopressors in patients with hypotension
- -Analgesics and sedatives
what is the absolute contraindication for empiric anticoagulation in suspected PE?
An absolute contraindication for empiric anticoagulation is a high risk of bleeding (e.g., recent surgery, hemorrhagic stroke, active bleeding)!
what are the options of initial anticoagulation of PE?
- -Low molecular weight heparin (LMWH) or fondaparinux in stable patients without renal insufficiency, especially in cancer patients
- -Unfractionated heparin (UFH) in patients with renal failure and those who may still require thrombolysis
what is the advantage of LMWH over UFH?
LMWH can be administered subcutaneously, guarantees a more rapid onset of anticoagulation, and has a longer duration of anticoagulant effect than UFH. aPTT-monitoring is not necessary. Fondaparinux is also more rapidly effective than UFH and requires no laboratory controls. The choice between fondaparinux and LMWH depends on costs, availability, and familiarity of use.
what is the long-term anticoagulation and prophylaxis (3–6 months) of PE?
- -Anticoagulation treatment is indicated for a minimum of three months after PE
- -The following agents may be used:
- -Warfarin (target INR 2–3)
- -LMWH
- -Direct oral anticoagulants (rivaroxaban, apixaban, edoxaban, dabigatran)
- -Patients with a hypercoagulable state with DVT or PE: heparin followed by 3–6 months of warfarin for the first event, 6–12 months for the second, and lifelong anticoagulation for further events
what is the prophylaxis of DVT?
• Ensure early postoperative ambulation.
• Avoid predisposing factors eg. discontinue contraceptive pill six weeks before elective surgery.
• Venous support stockings perioperatively
• Pneumatic compression stockings
• Prophylactic LMWH perioperatively
Hospitalized patients should receive prophylactic measures to help prevent DVT. These include early mobilization postoperatively, minimizing risk factors when possible, venous support stockings to encourage venous return and reduce venous stasis, and prophylactic LMWH given in the perioperative period.
what are the indications of thrombolytic therapy?
–In cases of massive PE causing right heart failure
–In hemodynamically unstable patients requiring resuscitation
Procedure: fibrinolysis, preferably with recombinant tissue-type plasminogen activator (tPA), e.g., alteplase
Most commonly systemic infusion via IV catheter
Alternatively, direct infusion of tPA into pulmonary artery via pulmonary arterial catheter
Administration of anticoagulants discontinued during thrombolysis
what are the indications of inferior vena cava filter placement?
- -In recurrent DVTs despite anticoagulation
- -If anticoagulation is contraindicated (e.g., high-risk of bleeding) in patients with a documented lower leg DVT
what are the complications of PE?
– Acute • Cardiac arrest • Pulmonary infarction • Haemoptysis • Pneumonia – Chronic • Chronic breathlessness • Pulmonary hypertension High risk of recurrence: without anticoagulant treatment ∼ 10% in the first year, ∼ 5% per year after Right ventricular failure Sudden cardiac death due to pulseless electrical activity Atelectasis (∼ 20% of cases) Pulmonary effusion Pulmonary infarction (∼ 10% of cases)
what are the complications of DVT?
–Pulmonary embolism
–Postthrombotic syndrome (chronic venous insufficiency)
Damage to bicuspid valves allows backflow, pooling of blood and venous hypertension
