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
