Pulmonary Embolism

Original Editor Uchechukwu Chukwuemeka

Top Contributors - Uchechukwu Chukwuemeka, Karen Wilson, Rachael Lowe, Kim Jackson and Lucinda hampton


Introduction[edit | edit source]

Pulmonary embolism (PE) is a blockage of one of the pulmonary arteries in the lungs. In most cases, a deep venous thrombosis (DVT) forms in the leg. Once dislodged, the thrombus travels to the lungs where it occludes the pulmonary artery. The condition is a medical emergency that requires prompt diagnosis and treatment.

Pathological Process[edit | edit source]

Thrombus formation occurs due to stasis in the deep veins, especially at the calf. The patient's initial cardiorespiratory status, and size and number of emboli affects the severity of changes in pulmonary blood flow and respiration. A small blockage of the pulmonary artery may not provoke symptoms, while a large embolus can be fatal. 

In the latter case, pulmonary embolism causes wasted ventilation as it increases the alveoli dead space, resulting in a ventilation-perfusion mismatch[1] and an increase in pulmonary artery pressures and right ventricular work.[2] Consequently, there is eventual right heart failure, accompanied by the left side of the heart due to decrease in blood volume and coronary perfusion to the left ventricle. Cardiac muscle dysfunction ensues, and the heart ceases to pump blood.

[3]

In rare cases, occlusion of the pulmonary artery can also occur due to non-thrombotic materials such as air, fat, amniotic fluid, bone, and organ fragments.

Prevalence/Incidence of PE[edit | edit source]

After myocardial infarction (MI) and cerebrovascular accidents (CVA), PE follows as the third leading cause of cardiovascular death.[4] Some persons with PE are asymptomatic with incidence of 2.6%[5] and upto 71.4% in patient with distal DVT.[6] The European guidelines for the diagnosis and management of PE report annual incidence rates of venous thrombosis and PE of approximately 0.5 to 1.0 per 1000 inhabitants. A national incidence of 0.6/1000/year was reported by a Swedish study done in 2005.[7]

Risk Factors[edit | edit source]

Thrombi, or blood clots, are due to hypercoagulation. Common risk factors include in the following:[8][9]

  • Serious limb injury, surgery, prolonged bed rest, and static lower limb posture for more than 6 hours
  • Trauma and spinal cord injury
  • Smoking
  • Oral contraceptives
  • Hormone replacement therapy
  • Cancer
  • Chemotherapy
  • Pregnancy and post-partum period
  • Advanced age (>40 years old)
  • Immobilizer or cast
  • Central venous catheterization

Being overweight and hypercholesterolemia increase the risk of fat embolism.

Clinical Presentation[1][edit | edit source]

  • Pyrexia
  • Dyspnea and/or Tachypnea
  • Crackle lung sound on chest auscultation
  • Prounced second heart sound
  • Pleuritic chest pain
  • Profuse sweating
  • Cough with hemoptysis
  • Tachycardia with rapid feeble pulse, arrhythmia
  • Hypotension, lightheadedness, dizziness (occasionally induced
  • by exercise only)
  • Syncope
  • Cyanosis

Several prediction tools can be used to help clinicians assess a patient's likelihood of having PE:[10]

Preliminary Lab Testing[edit | edit source]

Suspicion of PE should be based on a careful assessment of history, known risk factors, and physical examination.[9] From there, additional studies must be performed to confirm a diagnosis.

D-dimer and doppler ultrasound are non-specific tests that can rule in DVT and PE as possible diagnoses.[11][6] Electrocardiography can identify heart abnormalities that are more common with large embolisms.[9] Likewise, in conjunction with other cardiac tests, elevated cardiac troponins may increase suspicion of a massive embolism. Although, Chest X-rays are non-diagnostic, they are important for ruling out or uncovering alternative diagnoses such as pleural effusion.[12][13]

Diagnostic Imaging[edit | edit source]

Many imaging studies can be used to diagnose PE.[9] Among the most common are ventilation-perfusion scanning, computed tomographic angiography (CTA), and magnetic resonance imaging (MRI). CTA is the best diagnostic tool, as it is has the greatest specificity and sensitivity for detecting emboli in the pulmonary arteries.[9]

Ventilation-perfusion scanning is also highly diagnostic in the absence of cardiopulmonary disease. Per a review by the New England Journal of Medicine[9], under high clinical suspicion, "a normal perfusion lung scan effectively rules out acute pulmonary embolism."

Medical Management[edit | edit source]

Once diagnosed, a variety of medical interventions may be used to manage PE.

Anticoagulant Therapy

Anticoagulation is among the most common treatments for PE.[2][9] Fast-acting fibrinolytic agents such as heparin or pentasaccharide fondaparinux are typically administered.[9] These medications are prescribed with the goal of preventing blood clot progression.

Inferior Vena Cava Placement

An IVC filter may be placed  in patients with recurrent PE, contraindications to anticoagulation, or major bleeding complications with anticoagulation.[9] Although IVC filters can effectively reduce the incidence of PE, they may increase the incidence of DVT.

Embolectomy

Physiotherapy

The role of physiotherapy comes in when embolism has been controlled and no further clot is been formed. The main aim of physiotherapy is to restore a clear lung field and oxygen uptake to optimal level.This could be achieved by appropriate chest Physiotherapy and then progressed to endurance exercises such as bicycle ergometry, threadmill , hydrotherapy e.t.c. see...

[14]

Differential Diagnosis[15][edit | edit source]

Resources[edit | edit source]

  • Tran HA, Gibbs H, Merriman E, Curnow JL, Young L, Bennett A et al. New guidelines from the Thrombosis and Haemostasis Society of Australia and New Zealand for the diagnosis and management of venous thromboembolism. Med J Aust. 2019; 210(5):227-235.
  • British Thoracic Society guidelines for the management of suspected acute pulmonary embolism. Thorax 2003;58(6):470-483.
  • Konstantinides SV, Torbicki A. Management of pulmonary embolism: recent evidence and the new European guidelines. European Respiratory Journal 2014 44: 1385-1390; DOI: 10.1183/09031936.00180414
  • https://academic.oup.com/ptj/article/96/2/143/2686356

References[edit | edit source]

  1. ↑ 1.0 1.1 Hough, A. Physiotherapy in Respiratory Care; An evidence-based approach to respiratory and cardiac management. 3rd eds. United Kingdom: Nelson Thomes Ltd, 2001
  2. ↑ 2.0 2.1 Hillegass E. Essential of Cardiopulmonary Physical Therapy. 3rd ed. Missouri,St. Louis: Saunders Elsevier. 2011
  3. ↑ MedCram. Pulmonary Embolism Remastered - Pathophysiology, Symptoms, Diagnosis, DVT. Available from: http://www.youtube.com/watch?v=XKT6gHI2z4U[last accessed 29/4/2019]
  4. ↑ Weitz JI. Pulmonary embolism. In: Goldman L, Schafer AI, editors. Goldman's Cecil Medicine. 24th efition. Philadelphia, PA: Elsevier; 2011
  5. ↑ Dentali F, Ageno W, Becattini C, Galli L, Gianni M, Riva N et al. Prevalence and clinical history of incidental, asymptomatic pulmonary embolism: a meta-analysis.Thromb Res. 2010;125(6):518-22. doi: 10.1016/j.thromres.2010.03.016.
  6. ↑ 6.0 6.1 Krutman M, Wolosker N, Kuzniec S, de Campos Guerra JC, Tachibana A, de Almeida Mendes C. Risk of asymptomatic pulmonary embolism in patients with deep venous thrombosis. J Vasc Surg Venous Lymphat Disord. 2013;1(4):370-5. doi: 10.1016/j.jvsv.2013.04.002.
  7. ↑ Andersson T, Söderberg S. Incidence of acute pulmonary embolism, related comorbidities and survival; analysis of a Swedish national cohort. BMC Cardiovasc Disord. 2017; 17: 155. doi: 10.1186/s12872-017-0587-1
  8. ↑ What Else Could Raise My Chances of PE? Available from: https://www.webmd.com/lung/what-is-a-pulmonary-embolism [Accessed 29th April 2019].
  9. ↑ 9.0 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 Tapson VF. Acute pulmonary embolism. New England Journal of Medicine. 2008 Mar 6;358(10):1037-52.
  10. ↑ Essers BA, Prins MH. Methods to measure treatment satisfaction in patients with pulmonary embolism or deep venous thrombosis. Curr Opin Pulm Med. 2010;16(5):437-41.
  11. ↑ Edmondson, R. The causes and management of pulmonary embolism. Care Crit. Ill. 1194; 10:26-9.
  12. ↑ Elliott CG, Goldhaber SZ, Visani L, DeRosa M. Chest radiographs in acute pulmonary embolism. Results from the International Cooperative Pulmonary Embolism Registry. Chest. 2000;118(1):33-8.
  13. ↑ Shawn TSH, Yan LX, Lateef F. The chest X ray in pulmonary embolism: Westermark sign, Hampton's Hump and Palla's sign. What's the difference? Journal of Acute Disease. 2018; 7(3): 99-102
  14. ↑ MedCram. Pulmonary Embolism / Thromboembolism Updates Explained Clearly. Available from: http://www.youtube.com/watch?v=XKT6gHI2z4U[last accessed 29/4/2019]
  15. ↑ Squizzato A, Luciani D, Rubboli A, Di Gennaro L, Landolfi R, De Luca C et al. Differential diagnosis of pulmonary embolism in outpatients with non-specific cardiopulmonary symptoms. Intern Emerg Med. 2013;8(8):695-702.
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