Venous Thromboembolism (VTE)

• Most commonly manifested as pulmonary embolism (PE) and deep venous thrombosis (DVT), and is associated with significant morbidity and mortality
  • ⅓ of patients present with symptoms of DVT and ⅔ with PE 
  • Also manifests as superficial vein thrombosis (SVT), a less severe form of DVT 
• One of the most common life-threatening cardiovascular diseases in the US and with increasing incidence and mortality rates in Asia
• All patients admitted for major trauma, surgery or acute medical illness should be assessed for risk of VTE and bleeding before starting prophylaxis of VTE 
  • Studies show that appropriate VTE prophylaxis should be given to surgical patients in Asia who are at risk for VTE

Deep Vein Thrombosis (DVT)

• Frequent manifestation of VTE in which there is a blood clot blocking a deep vein
• Patients are generally asymptomatic with a calf DVT but becomes symptomatic with proximal extension of the DVT and venous outflow obstruction

Pulmonary Embolism (PE)

• Blockage of the blood vessels in the lungs usually due to blood clots from the veins, especially the veins in the legs and pelvis

• Virchow’s triad theorizes 3 factors contributing to the development of VTE: Hypercoagulability, endothelial damage, and stasis
• Hypercoagulability has been associated with factor V Leiden mutation and prothrombin gene mutation
  • Cancer also produces a hypercoagulable state due to the procoagulant activity produced by malignant cells and also secondary to effects of chemotherapeutic agents
• Major contributing risk factors include history of trauma, surgical procedures, spinal cord injury, long bone fractures, and previous VTE 

Deep Vein Thrombosis (DVT)

• Localized tenderness along the distribution of the deep venous system
• Unilateral or entire leg is swollen
• Calf swelling >3 cm compared to asymptomatic leg (measured 10 cm below tibial tuberosity)
• Pitting edema is greater in the symptomatic leg
• Collateral superficial veins (non-varicose)
• Erythema
• Warmth
• Superficial thrombophlebitis with a palpable cord over a superficial vein
• Phlegmasia cerulea dolens (blue leg) - deoxygenated hemoglobin in the stagnant veins causes a cyanotic hue in the leg
• Phlegmasia alba dolens (pale leg) - pallor in the edematous legs because the interstitial tissue pressure has exceeded capillary perfusion pressure

Pulmonary Embolism (PE)

• Suspicion of PE is usually raised by the clinical symptoms
  • Clinical findings are nonspecific and should not be the only criteria to diagnose PE
• Dyspnea, pleuritic chest pain, syncope and tachypnea [respiratory rate (RR) ≥20/minute] occur in most cases of PE
  • Dyspnea is the most frequent symptom, while tachypnea is its most frequent sign
  • Other signs and symptoms that may be present: Tachycardia [heart rate (HR) >100/minute], cough and hemoptysis, fever, diaphoresis, nonpleuritic chest pain, apprehension, rales, increasing pulmonic component of the 2nd heart sound, wheezing, hypotension, cyanosis, pleural rub, raised jugular venous pressure
  • PE should be suspected in cases of postoperative hypoxemia

Pleuritic Chest Pain

• Pleuritic chest pain with or without dyspnea is one of the most frequent presentations of PE
  • May suggest a small embolism located distally near the pleura that also causes pleural irritation

Isolated Dyspnea

• Isolated dyspnea may occur suddenly or progressively (over several weeks)
  • Usually due to a more central PE (not affecting the pleura)
  • May be associated with substernal angina-like chest pain that probably is representing right ventricular (RV) ischemia
  • Worsening dyspnea may be the only symptom that indicates PE in patients with preexisting heart failure (HF) or pulmonary disease

Syncope or Shock

• Syncope or shock is the hallmark sign of central PE and usually results in severe hemodynamic repercussions
  • Signs of hemodynamic compromise and reduced heart flow are also usually present (eg systemic arterial hypotension, oliguria, cold extremities and/or clinical signs of acute right heart failure)

Massive Pulmonary Embolism

• Dyspnea is usually the prime symptom and systemic arterial hypotension that requires pressor support is the predominant sign
  • Persistent hypotension is defined as a systolic blood pressure (SBP) <90 mmHg or a pressure drop of <40 mmHg for >15 minutes (or needing inotropic support) not caused by new-onset arrhythmia, hypovolemia or sepsis; or absence of pulse or sustained heart rate <40 beats/minute (bpm) with signs or symptoms of shock
• Syncope and altered mentation
• Renal insufficiency, hepatic dysfunction
• Severe respiratory distress or hypoxemia (eg cyanosis)

Transient or Reversible Provoking 

• Surgery within the past 4 weeks (eg hip or knee replacement) 
• Major trauma
• Immobilization for at least 3 days
• Bedridden for >3 days 
• Estrogen therapy
• Pregnancy/postpartum
• Lengthy travel, eg airline flight >8 hours

Persistent Provoking 

• Active cancer
• Active autoimmune disease
• Antiphospholipid antibody syndrome
• Chronic inflammatory states, eg inflammatory bowel disease 

Other Risk Factors   

• Increasing age
• Past medical history or family history of VTE
• Spinal cord injury 
• Lower limb fracture
• Myocardial infarction or hospitalization for atrial flutter/fibrillation or heart failure within the past 3 months 
• Congestive heart failure or respiratory failure 
• Obesity
• Varicose veins
• Blood transfusion and erythropoiesis-stimulating agents