Pulmonary embolism

Pulmonary embolism (PE) is a life-threatening condition resulting from dislodged thrombi occluding the pulmonary vasculature; right heart failure and cardiac arrest may ensue if not aggressively treated.

Common clinical features include dyspnoea, pleuritic chest pain, and hypoxaemia. There may also be evidence of a concurrent deep vein thrombosis. Hypotension, syncope, tachycardia, and signs of right heart failure are less common signs but are important to recognise as they suggest a high-risk PE with a larger clot burden and a higher mortality rate.

Clinical probability, assessed by a validated prediction rule and clinical judgement, is the basis for all diagnostic strategies for PE. Computed tomographic pulmonary angiography is the definitive diagnostic investigation.

Haemodynamically unstable patients require urgent primary reperfusion (usually thrombolysis), anticoagulation, and supportive care. Those at intermediate risk of a poor outcome require anticoagulation and ongoing monitoring; rescue reperfusion should be used if patients become haemodynamically unstable.

Ongoing anticoagulation therapy is indicated to reduce the risk of recurrent events or fatal PE.

PE is a consequence of thrombus formation within a deep vein of the body, most frequently in the lower extremities. Thrombus formation in the venous system occurs as a result of venous stasis, trauma, and hypercoagulability. These factors are collectively known as Virchow's triad.[1]Cervantes J, Rojas G. Virchow's legacy: deep vein thrombosis and pulmonary embolism. World J Surg. 2005;29 Suppl 1:S30-34. http://www.ncbi.nlm.nih.gov/pubmed/15818472?tool=bestpractice.com Approximately 51% of deep venous thrombi will embolise to the pulmonary vasculature, resulting in a PE.[2]Huisman MV, Büller HR, ten Cate JW, et al. Unexpected high prevalence of silent pulmonary embolism in patients with deep venous thrombosis. Chest. 1989 Mar;95(3):498-502. http://www.ncbi.nlm.nih.gov/pubmed/2920574?tool=bestpractice.com Venous thromboembolic disease is the preferred term to describe the spectrum of disease beginning with the risk factors of Virchow's triad, progressing to deep venous thrombosis, and resulting in life-threatening PE.

This topic covers PE in adults.