Deep Vein Thrombosis (DVT) 

1️⃣ What is Deep Vein Thrombosis?

Deep Vein Thrombosis (DVT) is the formation of a thrombus within the deep venous system, most commonly in the lower limbs. It is a major component of Venous Thromboembolism (VTE), along with pulmonary embolism (PE).

🔴 ICU  relevance:
DVT → Pulmonary embolism → Sudden death
Chronic DVT → Post-thrombotic syndrome
Massive iliofemoral DVT → Phlegmasia cerulea dolens

2️⃣ Common Sites of DVT

A. Lower Limb (Most common)

Classification by Location

B. Upper Limb DVT

Common in:

• Central venous catheters
• Malignancy
• Thoracic outlet syndrome
• Effort thrombosis (Paget-Schroetter)

3️⃣ Pathophysiology — Virchow’s Triad

Introduced by Rudolf Virchow

 1. Venous Stasis

• Immobilization
• ICU sedation
• Heart failure
• Paralysis

 2. Endothelial Injury

• Surgery
• Trauma
• Central line insertion

 3. Hypercoagulability

• Malignancy
• Pregnancy
• Estrogen therapy
• Thrombophilia

4️⃣ Risk Factors

Acquired

• Surgery (especially orthopedic)
• ICU stay >3 days
• Sepsis
• Malignancy
• Pregnancy
• OCPs
• Obesity
• Nephrotic syndrome

Inherited Thrombophilia

• Factor V Leiden
• Prothrombin mutation
• Protein C deficiency
• Protein S deficiency
• Antithrombin deficiency

5️⃣ Clinical Presentation

Classical Features

• Unilateral leg swelling
• Calf pain
• Warmth
• Erythema
• Dilated superficial veins

 50% cases are asymptomatic.

Red Flag

• Sudden dyspnea → suspect PE

6️⃣ Complications

Acute

• Pulmonary embolism
• Phlegmasia alba dolens
• Phlegmasia cerulea dolens (venous gangrene)

Chronic

• Post-thrombotic syndrome
• Chronic edema
• Hyperpigmentation
• Venous ulcers

7️⃣ Diagnosis

Step 1: Clinical Probability — Wells Score

Interpretation:

• ≥2 → DVT likely
• <2 → DVT unlikely

Step 2: D-Dimer

• High sensitivity
• Low specificity
• Rule out in low probability patients

Step 3: Compression Ultrasonography (Gold Standard Initial Test)

Finding:

• Non-compressible vein
• Echogenic clot
• Absent flow

❓ Can Compression Ultrasonography Cause Pulmonary Embolism?

 Why Doesn’t It Dislodge the Clot?

1️⃣ Nature of Venous Thrombus

Venous thrombi:

• Form in areas of low flow
• Are often adherent to vein wall
• Usually partially organized by the time of diagnosis

Once symptomatic, the clot is typically:

• Anchored proximally
• Not freely floating in most cases

2️⃣ What Actually Happens During Compression Ultrasound?

During the test:

• The probe applies gentle external pressure
• The aim is to see if the vein collapses
• A thrombus-containing vein does NOT compress

When CT / MR Venography?

• Suspected iliac vein thrombosis
• Inconclusive ultrasound

Prophylaxis

1.Mechanical Prophylaxis

Used when:

• Platelet <50k
• Active bleeding
• Recent surgery with bleeding risk
• Intracranial hemorrhage

Types:

• Intermittent pneumatic compression (IPC)
• Sequential compression device (SCD)
• Graduated compression stockings (less effective alone)

2.Pharmacologic Prophylaxis

LMWH (Preferred if stable renal function)

Example:Enoxaparin 

UFH

• CrCl <30 ml/min
• High bleeding risk
• AKI

8️⃣ Treatment (According to major international guidelines)

🔴 Immediate Anticoagulation

A. Direct Oral Anticoagulants(not in icu) (First Line if no contraindication)

• Apixaban
• Rivaroxaban
• Edoxaban
• Dabigatran

B. LMWH

Preferred in:

• Pregnancy(Continue 6 weeks postpartum ,minimum 3 months total)
• Hemodynamically stable patients
• Good renal function
• Low bleeding risk
• No urgent procedures planned
• Cancer-associated thrombosis (stable patient)

C. Unfractionated Heparin

• Renal failure
• High bleeding risk (easy reversal)

Duration of Therapy

9️⃣ Special Situations

1. Massive Iliofemoral DVT

• Consider thrombolysis
• Mechanical thrombectomy

2. IVC Filter

Indications:

• Absolute contraindication to anticoagulation
• Recurrent VTE despite adequate therapy

🔟  Every ICU patient must be assessed daily for VTE prophylaxis.

 Step 1: Assess VTE (Thrombosis) Risk

Critically ill patients are automatically high risk.
But we stratify formally using validated tools.

 1. Padua Prediction Score (Medical ICU)

Developed in University of Padua

≥4 → High risk → Give pharmacologic prophylaxis (if no bleeding risk)

 2. Caprini Score (Surgical ICU)

More detailed — used in post-operative patients.

 3. IMPROVE VTE Score (Common in ICU protocols)

Also predicts 3-month VTE risk.

 Step 2: Assess Bleeding Risk

This is equally important.

IMPROVE Bleeding Risk Score

Major factors:

• Active GI ulcer
• Recent bleeding (<3 months)
• Platelet <50,000
• Dual antiplatelet therapy
• INR >1.5 (not on anticoagulation)
• Hepatic failure
• Severe renal failure

High bleeding risk → avoid pharmacologic prophylaxis initially.