Deep Vein Thrombosis And Pulmonary Embolism

• Deep vein thrombosis (DVT) and pulmonary embolism (PE) together comprise a disease process called venous thromboembolism (VTE). A relatively common diagnosis (60,000 hospitalization/year for DVT).
• VTE may often be deadly, and as such cannot be missed during diagnostic workup in the emergency department (ED).

What is Deep vein system? 

• The deep venous system of the lower extremities includes the: 
  • Calf veins (anterior tibial, posterior tibial, and peroneal veins), 
  • Popliteal vein, 
  • Femoral veins, and the 
  • External iliac veins. 
• The superficial femoral vein, despite its name, is actually part of the deep and not superficial venous system. Difficult to diagnosis.

Atypical symptoms and presentation High index of suspicion and to understand the workup in ruling out this disease process in our ED patients.

Classic Presentation

• The classic presentation of PE includes complaints of shortness of breath or chest pain. Additionally, syncope as well as vague complaints of general malaise or functional deterioration may be presenting features. While often vague, patients may describe a pleuritic component to the chest pain (hurts worse with deep breaths). Unilateral leg symptoms (DVT symptoms-see above) may be present, as well as signs of right sided heart failure (jugular venous distention, peripheral edema). 

Diagnose

• Initial ABC evaluation of patient presenting with PE is important. 
• PE may present as mild shortness of breath, chest pain, fatigue, or a number of other non-specific symptoms. A massive pulmonary embolism can cause a patient to present in cardiac arrest with PEA (pulseless electrical activity). These patients may need to be intubated initially for airway support. As with other patients complaining of chest pain or shortness of breath, those with suspected PE should be placed on a cardiac monitor, have IV access, and be supplied supplemental oxygen as needed. 
• An initial EKG and CXR should be obtained in patients you are concerned about a PE to rapidly evaluate for other items on the differential diagnosis (MI, pneumonia, pneumothorax). Initial DVT symptoms may be subtle and nonspecific. Complaints include general leg pain or a cramping sensation, fullness in the calf, swelling, edema or tenderness on palpation.

Differential diagnosis

• The differential diagnosis may include musculoskeletal strain or tear, cellulitis, superficial thrombophlebitis, venous insufficiency, lymphedema, or popliteal (Bakers) cyst. 

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Classical finding on Physical Examination

• Unilateral swelling or edema of the extremity 
• Tenderness to palpation 
• Palpable venous “cord”
• Homan’s sign is the classic sign of pain in the calf on passive dorsiflexion of the foot with the knee in extension. 
• This test is neither sensitive nor specific in ruling in or ruling out DVT of the extremity. 

History and Primary Survey

• You should include all the pertinent information to develop a differential and calculate a pretest probability. Risk factors may help estimate the risk of venous thromboembolism in patients. 
• Calculate a pretest probability. The Wells score is a clinical decision rule developed to assist in the determining the pretest probability of DVT as well as PE, and to help guide further diagnostic workup. 

Wells Pretest Probability for DVT

• Score: 0 = low probability, 1-2 = moderate, >3 = High 
• Entire leg swollen (1 point)
• Calf swelling at least 3 cm greater than other side (1 point) 
• Pitting edema confined to symptomatic leg (1 point) 
• Collateral superficial veins (non-varicose) (1 point) 
• Previously documented DVT (1) 
• Alternative diagnosis at least as likely as DVT (-2 points) 

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Pulmonary Embolism 

Classic Presentation

• The most common vital sign abnormality seen is tachycardia in the setting of normal pulse oxygenation. 

Factors increase the risk of thromboembolism

• Clinical symptoms of DVT (3 points) 
• Other diagnosis less likely than pulmonary embolism (3 points) 
• Heart rate > 100 (1.5 points)
• Immobilization (3 days) or surgery in the past 4 weeks (1.5 points) 
• Previous DVT/PE (1.5 points) 
• Hemoptysis (1.0 points)
• Malignancy (1 points) 

Clinical Probability: Low probability less than 2, Moderate 2-6, High more than 6.

Diagnose

• A CXR is useful to rule out other diagnosis such as pneumothorax, congestive heart failure, pneumonia. Sometimes one can see unilateral atelectasis as suggestive of PE, or Hamptons’ hump (pulmonary infarct leading to pleural based wedge-shaped area of infiltrate) or Westermarks’s sign (unilateral lung oligemia). 
• X-ray of the lower extremity may be helpful in the workup of DVT if you are concerned about possible skeletal trauma related to the leg pain or swelling. 
• EKG findings are usually nonspecific. The most common EKG abnormality is sinus tachycardia, although other findings such as right bundle branch block or evidence of right heart strain (an S wave in lead I and Q and inverted T in lead III, the S1Q3T3 pattern) may be seen.

D-Dimer Test

• The utility of a D-dimer directly relates to the pretest probability that the patient has a DVT or PE. D-dimer is a protein derived enzymatic breakdown of cross-linked fibrin. Increased levels indicate the presence of clot formation somewhere in the body. 
• It can be elevated in many diseases, including malignancy, infection, inflammation, MI, strokes, advanced age, and pregnancy and is therefore a very nonspecific test that cannot be used to definitely diagnose any disease process, including DVT and PE.
• To further complicate matters, there are also several different laboratory techniques of measuring D-dimer that may affect the sensitivity of the test. 

Specific Test for DVT

• Venous duplex ultrasonography is currently the diagnostic test of choice in most centers for DVT. In the hand of a experienced sonographer, the sensitivity and specificity is approximately 95%. 
• The classic finding on ultrasound for a positive study is the inability to fully compress the vein in the deep venous system of the leg. Other processes (such as a Baker cyst) can also be seen on ultrasound. 

Specific Test for Pulmonary thromboembolism

• Patients with a moderate or high pre-test probability for PE should have a imaging study with either CT Pulmonary Angiography (CTPA) or V/Q scan. CTPA is now the accepted study to diagnosis PE in most emergency departments. 
• A CT can also show other possible etiologies of the symptoms including pneumonia, masses, effusions, aortic dissection or pneumothorax. 

Treatment

• Those with confirmed PE or DVT on imaging should be treated with anticoagulation. Either unfractionated heparin or low-molecular weight heparins (e.g., enoxaparin) may be used in most cases. This may be started before imaging confirmation in patient with a high pre-test probability of the disease. Generally, patients with PE should be admitted to he hospital for anticoagulation. If the PE is large enough to case cardiopulmonary compromise (large A-a gradient, low BP or pulse ox), ICU admission should be considered. 
• Patients with an isolated DVT without PE sometimes can be sent up to receive anticoagulation at home (subcutaneous enoxaparin) with oral anticoagulation (warfarin). This requires teaching and proper coordination with social services and primary care physicians. 

Contraindications to anticoagulation

• Contraindications to anticoagulation include patients with active bleeding (cerebral or GI) as well as patients with previous reaction to heparins. These patients may benefit from having a inferior vena ava (IVC) filter placed. 

Thrombolytic Therapy

• Thrombolytic therapy in the setting of PE is controversial and indicated in the setting of a massive PE with significant cardiopulmonary compromise or submassive PE with evidence of right heart strain (most commonly echocardiographic diagnosis). 

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Hope you found this blog helpful for your NEET SS Pulmonology Preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.