New Pulmonary Embolism: DVT to PE
CPDTime.
13m
Published: 12 July 2021
Throughout history, pulmonary embolism (PE) has almost always been diagnosed on the autopsy table. In other words, it was considered a ‘terminal event’ (Doherty 2017).
Today, PE is seen as a modern-day medical dichotomy: we understand its minutia and yet, somehow, still fail to diagnose or tackle it appropriately.
Appropriately treated, pulmonary embolism need not live up to its historical reputation as a life-ender.
Pulmonary Embolism Facts and Figures
Australia experiences approximately 17 000 new cases of venous thromboembolism annually (Tran et al. 2019), with pulmonary embolism accounting for 4 out of 10 of these cases (Skinner 2013).
Although PE is a significant factor in mortality and morbidity, the latest Australian and UK statistics on deaths due to pulmonary embolism are much lower than in the United States.
According to the most recent available statistics, PE accounts for only 0.2% and 0.4% of all annual deaths in Australia and the UK respectively (Doherty 2017). These are far smaller mortality rates than seen in the US, where it’s estimated that up to 100 000 people die from DVT/PE every year (CDC 2020a).
What is a Pulmonary Embolism?
Pulmonary embolism (PE) is a natural consequence of a cascade of unfortunate events that begin with a thrombus formation, typically in a deep vein of the legs, thighs or pelvis (Fig. 1).
With venous thromboembolism events, where there is smoke, there is usually fire. Three risk factors, collectively described as the Virchow triad, are the ‘smoke’ that occurs prior to a PE diagnostic fire.
Virchow's Triad
Virchow's triad consists of:
- Hypercoagulability (blood disorders that increase the risk of clotting), for example, an inherited Factor V Leiden mutation
- Abnormal blood flow, for example, stasis due to obesity or immobility
- Vessel wall injury (aka endothelial Injury), for example, damage from smoking or sepsis.
(Garmo, Bajwa & Burns 2020; Kushner, West & Pillarisetty 2020; Ausmed 2021)
The presence of these risk factors places patients at a significantly elevated risk of the venous event turning into a much bigger pulmonary problem.
In fact, over 50% of patients with a DVT will eventually end up with a diagnosis of PE (Merli et al. 2017).
Types of Pulmonary Embolism Presentations
Not all pulmonary emboli present the same.
It is not enough for clinicians to eyeball a patient’s clinical presentation to determine the need for medical imaging to rule out PE.
Instead, clinicians should use several valid and reliable checklists comprised of clinician characteristics in order to rule out the likelihood of PE. An example is this checklist by Kline et al. (2008):
A patient who presents with NONE of the following characteristics has a pretest probability of having a PE of less than 1%:
- Initial heart rate > 100 beats/min
- Initial oxygen saturation < 94% on room air
- Unilateral leg swelling
- Haemoptysis
- Surgery or trauma within four weeks
- History of venous thromboembolism
- Oestrogen use.
If the patient has at least one of the above characteristics, then PE cannot be ruled unlikely without further assessment.
Pulmonary Embolism Causes
Deep vein thromboses (DVT) can be caused by anything that prevents normal circulation in the legs, including bed rest or limited movement, injury, bracing, surgery, or even certain types of medicines (see risk factors for more info).
DVTs are largely preventable, which means that PEs are also largely preventable.
Patients who maintain a healthy weight, exercise (or at least do not maintain a sedentary lifestyle) and follow directions related to post-surgery care or bedrest are far less likely to develop a DVT.
The most prominent signs of a DVT are:
- Redness or discolouration
- Swelling
- Pain, especially a cramping sensation in the calf (Fig. 2).
A Homans’ sign is no longer considered a sensitive or specific test for DVT (Ambesh, Obiagwu & Shetty 2017).
Pulmonary Embolism Symptoms
View Full Lecture! →
Pulmonary embolism typically begins with the migration of a thrombus formation (Fig. 3), usually from the deep veins of the leg to the small blood vessels of the lungs. The clot lodges in these smaller pathways and blocks blood flow, potentially leading to tissue death.
It is important to know that patients can suffer a PE without any prior symptoms of a DVT.
Signs and symptoms of PE can include:
- Laboured breathing
- Elevated heart rate
- Arrhythmias
- Pain or discomfort in the chest
- Greater chest pain with coughing or deep breathing
- Coughing up blood
- Hypotension
- Lightheadedness
- Loss of consciousness.
(CDC 2020b)
Pulmonary Embolism Risk Factors
Risk factors for DVT (and thus for PE) include many events that tend to lead to injuries to the venous structures of the leg, thigh, hip or pelvis.
Fractures, surgery and significant muscle tears are all conditions that create the potential for DVT formation.
Individuals with slow blood flow have an elevated risk; this flow problem can be due to prolonged sitting from long car rides or aeroplane flights, bed rest, or paralysis.
Pregnancy, hormone replacement therapy and contraceptive medicines are also major culprits due to a common theme: they cause an increase in oestrogen to be delivered to the body.
Central venous catheters must be closely monitored.
Even certain medical conditions such as cardiopulmonary disease , inflammatory bowel conditions and obesity can increase the risk.
Certainly, family history of DVT or PE or any type of genetic clotting disorder will also elevate the odds.
These odds increase further in older adults.
Pulmonary Embolism Diagnosis and Testing
Over time, clinicians have developed working models to determine the probability of a PE diagnosis. There are many available, but the Wells model is easy to use and well established.
Wells' Score for Clinical Prediction
Wells' Clinical Prediction Rule for Pulmonary Embolism
View the entire lecture, Recognising a Clot, and more from this conference:
| Active cancer (patient receiving treatment for cancer within 6 months or currently receiving palliative treatment) | 1 |
| Hemoptysis | 1 |
| History of deep venous thrombosis or pulmonary embolism | 1.5 |
| Surgery or bedridden for 3 days or more during the past 4 weeks | 1.5 |
| Heart rate > 100 beats/min | 1.5 |
| Pulmonary embolism judged to be the most likely diagnosis | 3 |
| Clinical signs and symptoms compatible with deep venous thrombosis | 3 |
- A score of under 2 indicates a low probability of pulmonary embolism.
- A score of 2–6 indicates an intermediate probability of PE.
- A score of more than 6 indicates a high probability of pulmonary embolism.
(Streiff et al. 2016)
Individuals who score a high probability should skip the D-dimer assay and go immediately to imaging (CT angiography), which will either confirm or refute the presence of a PE.
Individuals with a moderate score should be tested with a high sensitivity D-dimer assay. If a high sensitivity D-dimer assay is not available, the patient should be imaged immediately with a CT angiography.
A computed tomographic pulmonary angiography (CTPA) is the standard diagnostic imaging tool used to determine the presence of a PE (Fig. 4). This test allows clinicians to visualise the small vessels of the lungs through the use of a contrast dye injected into a vein.
Other tests, such as ventilation-perfusion scans (Fig. 5) and pulmonary angiography, can also be used to diagnose PE.
Magnetic resonance imaging (MRI) can also be useful, but it is typically reserved for special populations where the use of radio waves is preferable to the use of X-rays, or where contrast dyes are not tolerated.
Pulmonary Embolism Treatment
The best course of action is always a good defensive strategy.
Compression stockings and vertical immersion in water (a swimming pool) are both great strategies designed to prevent DVTs and PEs (Fig. 6).
Medicines
Medicine may be used for both the prevention and treatment of DVTs and PEs.
If properly prescribed, medicines such as anticoagulants and thrombolytics can nip the problem in the bud.
Anticoagulants are often referred to as ‘blood thinners’, but this is not actually what they do. Instead, they reduce the ability of blood to clot, allowing the body time to reduce the size of the clot by reabsorption. They also make it less likely that the blood will clot again in the near future.
All anticoagulants increase the likelihood of bruising and bleeding, however, so this means patients are required to remain under monitoring to determine that they have not over (or under) medicated.
Anticoagulants can be injected (e.g. heparin or fondaparinux) or swallowed (warfarin, dabigatran, apixaban, and others).
Thrombolytics work to dissolve clots. They are more aggressive than anticoagulants, with a greater likelihood of uncontrolled bleeding, so they are reserved for more severe situations (Streiff et al. 2016).
Two other management strategies are available if medicines do not do the job. A filter can be placed in the inferior vena cava in order to prevent any clots from migrating from the legs into the lungs (Fig. 7).
This is a prevention strategy and will do nothing after the fact. In contrast, thrombectomy and embolectomy are rare surgical procedures that are used to remove a clot in the legs or lungs, respectively (Streiff et al. 2016).
Pulmonary Embolism Prevention
PE, although serious, can be prevented when appropriate measures are taken.
The first step to prevent PE is becoming aware of the risk. If you are at an increased risk, a doctor can recommend medicines or graduated compression stockings to help prevent a DVT from occurring.
As the risk of PE also increases when sitting for extended periods of time, this can be mitigated by getting up to walk, wearing loose-fitting clothes while travelling, and exercising your legs while seated.
Stretching your leg muscles by lifting your heels off the ground and setting them down again (Fig. 8) is a good way to do this. Finally, maintaining a healthy weight and active lifestyle is key to reducing the risk of PE (Konstantinides et al. 2018).
Complications of Pulmonary Embolism
As many as half of PE patients may suffer from complications (Klok et al. 2014).
Common complications include decreased quality of life, functional limitations, incomplete thrombus resolution, and abnormal pulmonary artery pressure and right ventricular function, among others.
OOne of the most severe complications, chronic thromboembolic pulmonary hypertension (CTEPH), is associated with a high risk of death. It occurs in just under 0.1% of post-PE patients but may be underdiagnosed due to presenting in a clinically similar way to PE (Guérin et al. 2014).
Identifying and correctly diagnosing CTEPH and other PE-related complications should be a primary concern of post-PE follow-up (D’Agostino et al. 2017).
Conclusion
Pulmonary embolism is a potentially preventable condition. It is also potentially life-ending.
As already discussed, the best clinical outcome is when the embolism never makes it to the lungs. And the best way to prevent the embolism from migrating to the lungs is to prevent it from ever forming in the lower extremities in the first place.
Clinician management of PE has changed over the years, with many excellent tools available to clinicians to allow them to bypass unnecessary tests and delay times.
With PE, time management is the most important treatment tool of them all.
Additional Resources
- Venous Thromboembolism Prevention Clinical Care Standard | ACSQHC
- An Introduction to Blood Clots | Ausmed Article
- Compression Stockings: Application, Removal and Care | Ausmed Article
- Venous Thromboembolism: Symptoms and Prevention | Ausmed Article
- The Clotting Cascade - Understanding Coagulation | Ausmed Lecture
- Recognising a Clot - Signs and Symptoms | Ausmed Lecture
References
- Ambesh, P, Obiagwu, C & Shetty, V 2017, ‘Homan’s Sign for Deep Vein Thrombosis: A Grain of Salt?’, Indian Heart J., vol. 69, no. 3, viewed 13 July 2021, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5485383/
- Ausmed Editorial Team 2021, ‘An Introduction to Blood Clots’, Ausmed, 19 May, viewed 8 July 2021, https://www.ausmed.com.au/cpd/articles/blood-clots
- Centers for Disease Control and Prevention 2020a, Data and Statistics on Venous Thromboembolism, CDC, viewed 8 July 2021, https://www.cdc.gov/ncbddd/dvt/data.html
- Centers for Disease Control and Prevention 2020b, What is Venous Thromboembolism?, CDC, viewed 8 July 2021, https://www.cdc.gov/ncbddd/dvt/facts.html
- Cervantes J & Rojas G 2005, ‘Virchow’s Legacy: Deep Vein Thrombosis and Pulmonary Embolism’, World Journal of Surgery, vol. 29, Sup. 1, S30-34, viewed 12 April 2018, https://www.ncbi.nlm.nih.gov/pubmed/15818472
- D’Agostino, C, Zonzin, P, Enea, I, Gulizia, M M, Ageno, W, Agostoni, P, Azzarito, M, Becattini, C, Bongarzoni, A, Bux, F, Casazza, F, Corrieri, N, D’Alto, M, D’Amato, N, D’Armini, A M, De Natale, M G, Di Minno, G, Favretto, G, Filippi, L, Grazioli, V, Palareti, G, Pesavento, R, Roncon, L, Scelsi, L & Tufano, A 2017, ‘ANMCO Position Paper: Long-Term Follow-Up Patients With Pulmonary Thromboembolism’, European Heart Journal Supplements: Journal of the European Society of Cardiology, vol. 19, Supp. D, D309-D332, viewed 12 April 2018, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5520763/
- Doherty, S 2017, ‘Pulmonary Embolism: An Update’, Australian Family Physician (Chest Pain), vol. 46, no. 11, pp. 816-20, viewed 12 April 2018, https://www.racgp.org.au/afp/2017/november/pulmonary-embolism/
- Garmo, C, Bajwa, T & Burns, B 2020, ‘Physiology, Clotting Mechanism’, StatPearls, viewed 11 May 2021, https://www.ncbi.nlm.nih.gov/books/NBK507795/
- Guérin, L, Couturaud, F, Parent, F, Revel, M P, Gillaizeau, F, Planquette, B & Sanchez, O 2014, ‘Prevalence of Chronic Thromboembolic Pulmonary Hypertension After Acute Pulmonary Embolism’, Thrombosis and Haemostasis, vol. 112, no. 3, pp. 598-605, viewed 12 April 2018, https://www.ncbi.nlm.nih.gov/pubmed/24898545
- Kline, JA, Courtney, D M, Kabrhel, C, Moore, CL, Smithline, H A, Plewa, M C, Richan, P B, O’Neil, B J & Nordenholz, K 2008, ‘Prospective Multicenter Evaluation of the Pulmonary Embolism Rule‐Out Criteria’, Journal of Thrombosis and Haemostasis, vol. 6, no. 5, pp. 772-80, viewed 12 April 2018, https://pubmed.ncbi.nlm.nih.gov/18318689/
- Klok, F A, Van der Hulle, T, Den Exter, P L, Lankeit, M, Huisman, M V & Konstantinides, S 2014, ‘The Post-PE Syndrome: A New Concept for Chronic Complications of Pulmonary Embolism’, Blood Reviews, vol. 28, no. 6, pp. 221-6, viewed 12 April 2018, https://www.ncbi.nlm.nih.gov/pubmed/25168205
- Konstantinides, S V, Barco, S, Lankeit, M & Meyer, G 2016, ‘Management of Pulmonary Embolism: An Update’, Journal of the American College of Cardiology, vol. 67, no. 8, pp. 976-90, viewed 12 April 2018, https://www.ncbi.nlm.nih.gov/pubmed/26916489
- Kushner, A, West, W P & Pillarisetty, L S 2020, ‘Virchow Triad’, StatPearls, viewed 12 May 2021, https://www.ncbi.nlm.nih.gov/books/NBK539697/
- Merli, G, Eraso, LH, Galanis, T & Ouma, G 2017, ‘Pulmonary Embolism’, BMJ Best Practice, viewed 12 April 2018, https://bestpractice.bmj.com/topics/en-us/116
- Tran, H A 2019, ‘New guidelines from the Thrombosis and Haemostasis Society of Australia and New Zealand for the Diagnosis and Management of Venous Thromboembolism’, Medical Journal of Australia, viewed 7 July 2021, https://www.thanz.org.au/resources/thanz-guidelines
- Skinner, S 2013, ‘Pulmonary Embolism: Assessment and Imaging’, Australian Family Physician (General Practice Psychiatry), vol. 42, no. 9, pp. 628-32, viewed 12 April 2018, https://www.racgp.org.au/afp/2013/september/pulmonary-embolism/
- Streiff, M B, Agnelli, G, Connors, J M, Crowther, M, Eichinger, S, Lopes, R, McBane, R D, Moll, S & Ansell, J 2016, ‘Guidance for the Treatment of Deep Vein Thrombosis and Pulmonary Embolism’, Journal of Thrombosis and Thrombolysis, vol. 41, no. 1, pp. 32-67, viewed 12 April 2018, https://link.springer.com/article/10.1007/s11239-015-1317-0
Author
Andrea Salzman View profile
Andrea Salzman, MS, PT graduated from the University of Alabama at Birmingham with a Master’s degree in physical therapy in 1992. Over the last two decades, she has held numerous prominent leadership roles in the physical therapy field, with a heavy emphasis on academic writing and administrative functions. Between 1995 and 1998, Salzman served as the Editor-in-Chief of an American Physical Therapy Association (APTA) journal. In 2010, Salzman received one of the highest honors given to a physical therapist from the American Physical Therapy Association, the Judy Cirullo Leadership Award. Between 2012 and the present, Salzman has written 12 physical therapy courses for Care2Learn, Relias Learning and reviewed over 100 other course offerings. Currently, Salzman continues in her writing, leadership and administrative roles at Aquatic Therapy University and 10K Health.
