Pulmonary embolism treatment approach
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Editor(s)-In-Chief: The APEX Trial Investigators, C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Kashish Goel, M.D.; Ujjwal Rastogi, MBBS [2]; Cafer Zorkun, M.D., Ph.D. [3]
Overview
Pulmonary embolism (PE) is a potentially lethal condition, with a mortality rate close to 30 percent without treatment. Thus, prompt therapy is of utmost important. In most cases, anticoagulant therapy is the mainstay of treatment. A proposed treatment algorithm is presented at the end of this chapter.
Risk stratification
One of the most important aspects in the care of a patient with acute PE is triage or early risk stratification.
- Low-risk PE: Therapeutic anticoagulation, unless contraindicated.
- Submassive PE: If the patient is hemodynamically stable without major RV dysfuncti[[ or infarction, therapeutic anticoagulation should be started. In some cases, thrombolysis may be indicated.
- Massive PE: Thrombolysis is indicated and ICU admission may be required. Initial supportive therapies in these patients may include:
- Respiratory support with oxygen for hypoxemic patients or mechanical ventilation in cases of severe hypoxemia or respiratory failure.
- Hemodynamic support with intravenous fluids or intravenous vasopressors for hypotensive patients. Intravenous fluids should be administered cautiously, as increased right ventricular load can disable the right ventricular oxygen supply-to-demand balance.[1]
- If anticoagulation is contraindicated, an IVC filter is recommended.
Initial treatment
Anticoagulation
Most common reason for mortality is recurrent PE, occurring within the few hours of the initial event[2]. Anticoagulation is the cornerstone of therapy in acute pulmonary embolism[2][3]. After initial risk stratification, immediate treatment should be started based on the following points[4][5][6]:
- Initial treatment with parenteral anticoagulants including subcutaneous Low molecular weight heparin(such as enoxaparin and dalteparin), subcutaneous Fondaparinux or intravenous unfractionated heparin, unless contraindicated.
- ACCP guidelines[4] recommend low molecular weight heparin or fondaparinux over intravenous unfractionated heparin.
- Anticoagulation should be started while awaiting confirmation tests, if there is moderate-to-high clinical suspicion of PE.
- Vitamin K antagonists like warfarin should be started the same day and parenteral anticoagulation should be continued for at least 5 days and preferably, until INR in 2.0 or above for 1-2 days.
- In patients with suspected or confirmed heparin-induced thrombocytopenia, lepirudin or argatroban should be used.
- Other salient features:
- Prevents further clot formation, so should be started as early as possible.
- It has no effect on pre-existing clot lysis.
- It has no effect in decreasing the size of thrombus.
- Warfarin therapy often requires frequent dose adjustment and monitoring of the INR. In PE, INRs between 2.0 and 3.0 are generally considered ideal.
- Anticoagulation should be used with caution, because certain conditions like pericardial tamponade and aortic dissection can mimic pulmonary embolism, but the use of anticoagulants is contraindicated in these medical conditions.
Thrombolysis
- Thrombolysis is indicated in patients with a massive PE or those with a submassive PE who develop or are at risk of developing hypotension (SBP < 90 mmHg), unless contraindicated.
- Administration of a fibrinolytic is recommended via a peripheral intravenous catheter.
- FDA recommends infusion dose of alteplase 100 mg as a continuous infusion over 2 hours, supported by AHA[5] and ACCP guidelines[4].
- Withhold anticoagulation during these 2 hours of fibrinolytic infusion.
- The role of thrombolysis in submassive PE in not established at this point[7]. Two ongoing trials are investigating this.
- No large clinical trial has demonstrated mortality benefit of thrombolytic therapy. However, it helps by accelerating clot lysis, improving pulmonary perfusion and right ventricular function[8][9]
To read more about dosage, contraindications and guidelines, click here.
Surgical procedures
- Catheter-assisted thrombus removal is recommended in patients with massive PE, who have contraindications or failed thrombolysis, or are in shock that will cause death before thrombolysis takes effect (hours).
- Pulmonary embolectomy is recommended if a patient with above conditions fails catheter-assisted embolectomy.
IVC filter
- IVC filter is indicated in whom anticoagulation is contraindicated.
- Anticoagulation should be restarted, once the contraindication is resolved.
Long-term treatment
- After initial treatment in the hospital, patient should continue anticoagulation for 3 months for an unprovoked PE.
Warfarin therapy is usually continued for 3-6 months, or "lifelong" if there have been previous DVTs or PEs, or none of the usual risk factors is present. An abnormal D-dimer level at the end of treatment might signal the need for continued treatment among patients with a first unprovoked pulmonary embolus.[10]
Extended anticoagulation
'Extended treatment should be considered in patients with:
- Active Cancer.
- Unprovoked Pulmonary embolism.
- Recurrent venous thromboembolism.
Indefinite treatment refers to continued anticoagulation without a pre-scheduled stop date.
If another episode of PE occurs under warfarin treatment
- The INR window may be increased to e.g. 2.5-3.5 (unless there are contraindications) or
- Anticoagulation may be changed to a different anticoagulant e.g. low molecular weight heparin.
Anticoaulation may be stopped because of:
- Risk of bleeding.
- Change in patients preference.
Specific circumstances
In patients with an underlying malignancy, low molecular weight heparin is favored over warfarin based on the results of the CLOT trial.[11]
Similarly, pregnant women are often maintained on low molecular weight heparin to avoid the known teratogenic effects of warfarin.
- Subcutaneous or Intravenous Low molecular weight heparin.
- Hemodynamically stable patients.
- Thrombolysis
- High Risk Hemodynamically stable patients.
- Hemodynamically Unstable patients.
- Percutaneous mechanical thrombectomy.
- High risk patients with absolute contraindications to Thrombolytics.
- Patients with failed Thrombolysis.
- Low molecular weight heparin is preferred over Vitamin K antagonist.
Newer anticoagulants
These are a class of anticoagulant drugs which act directly upon Factor X in the coagulation cascade, without using antithrombin as a mediator.Advantages of orally administered direct Xa inhibitors lie in the fact that they have a predictable effect, do not require frequent monitoring or re-dosing, are given through the mouth and not by injection and have few (known) drug interactions. Disadvantages include the currently limited prospective experience and the theoretical interactions with statin medication, as they are metabolized at least in part by the same cytochrome enzyme, CYP3A4.
Treatment algorithm
| Stabilize the patient | |||||||||||||||||||||||||||||||||||||
| Is anticoagulation contraindicated ? | |||||||||||||||||||||||||||||||||||||
| Yes | No | ||||||||||||||||||||||||||||||||||||
| Diagnostic evaluation | Anticoagulate with SC LMWH or IV UFH | ||||||||||||||||||||||||||||||||||||
| PE excluded | PE confirmed | Diagnostic evaluation | |||||||||||||||||||||||||||||||||||
| No further Treatment | Inferior vena cava filter | PE excluded | PE confirmed | ||||||||||||||||||||||||||||||||||
| Discontinue Anticoagulants | Clinicaly severe enough to need Thrombolysis | ||||||||||||||||||||||||||||||||||||
| Yes | No | ||||||||||||||||||||||||||||||||||||
| Is thrombolytic Contraindicated? | Continue Anticoagulants | ||||||||||||||||||||||||||||||||||||
| Yes | No | ||||||||||||||||||||||||||||||||||||
| Surgical emblectomy or catheter based interventions | Hold Anticoagulation, Give Thrombolytics then resume Anticoagulations | ||||||||||||||||||||||||||||||||||||
| Patient shows clinical improvement | |||||||||||||||||||||||||||||||||||||
| No | Yes | ||||||||||||||||||||||||||||||||||||
| Surgical emblectomy or catheter based interventions | Continue anticoagulation | ||||||||||||||||||||||||||||||||||||
Compression Stockings
Treatment Protocol[12]
Stabilize the patient
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Initial Treatment options (≤5 Days)
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| Long term treatment (≥3 Month) (INR target, 2.0-3.0) | |||||||||||||||||||
| Extended treatment (Indefinite) (INR target, 2.0-3.0 OR 1.5-1.9) | |||||||||||||||||||
References
- ↑ Mercat A, Diehl JL, Meyer G, Teboul JL, Sors H (1999). "Hemodynamic effects of fluid loading in acute massive pulmonary embolism". Crit. Care Med. 27 (3): 540–4. PMID 10199533. Retrieved 2011-12-12. Unknown parameter
|month=ignored (help) - ↑ 2.0 2.1 Carson JL, Kelley MA, Duff A, Weg JG, Fulkerson WJ, Palevsky HI, Schwartz JS, Thompson BT, Popovich J, Hobbins TE (1992). "The clinical course of pulmonary embolism". N. Engl. J. Med. 326 (19): 1240–5. doi:10.1056/NEJM199205073261902. PMID 1560799. Retrieved 2011-12-12. Unknown parameter
|month=ignored (help) - ↑ Goldhaber SZ, Visani L, De Rosa M (1999). "Acute pulmonary embolism: clinical outcomes in the International Cooperative Pulmonary Embolism Registry (ICOPER)". Lancet. 353 (9162): 1386–9. PMID 10227218. Retrieved 2011-12-12. Unknown parameter
|month=ignored (help) - ↑ 4.0 4.1 4.2 Kearon C, Akl EA, Comerota AJ; et al. (2012). "Antithrombotic therapy for VTE disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines". Chest. 141 (2 Suppl): e419S–94S. doi:10.1378/chest.11-2301. PMID 22315268. Unknown parameter
|month=ignored (help) - ↑ 5.0 5.1 Jaff MR, McMurtry MS, Archer SL; et al. (2011). "Management of massive and submassive pulmonary embolism, iliofemoral deep vein thrombosis, and chronic thromboembolic pulmonary hypertension: a scientific statement from the American Heart Association". Circulation. 123 (16): 1788–830. doi:10.1161/CIR.0b013e318214914f. PMID 21422387. Unknown parameter
|month=ignored (help) - ↑ Torbicki A, Perrier A, Konstantinides S; et al. (2008). "Guidelines on the diagnosis and management of acute pulmonary embolism: the Task Force for the Diagnosis and Management of Acute Pulmonary Embolism of the European Society of Cardiology (ESC)". Eur. Heart J. 29 (18): 2276–315. doi:10.1093/eurheartj/ehn310. PMID 18757870. Unknown parameter
|month=ignored (help) - ↑ Dong B, Jirong Y, Liu G, Wang Q, Wu T. Thrombolytic therapy for pulmonary embolism. Cochrane Database Syst Rev 2006;(2):CD004437. PMID 16625603.
- ↑ Konstantinides S, Geibel A, Heusel G, Heinrich F, Kasper W (2002). "Heparin plus alteplase compared with heparin alone in patients with submassive pulmonary embolism". N. Engl. J. Med. 347 (15): 1143–50. doi:10.1056/NEJMoa021274. PMID 12374874. Retrieved 2011-12-13. Unknown parameter
|month=ignored (help) - ↑ Levine M, Hirsh J, Weitz J, Cruickshank M, Neemeh J, Turpie AG, Gent M (1990). "A randomized trial of a single bolus dosage regimen of recombinant tissue plasminogen activator in patients with acute pulmonary embolism". Chest. 98 (6): 1473–9. PMID 2123152. Retrieved 2011-12-21. Unknown parameter
|month=ignored (help) - ↑ Palareti G, Cosmi B, Legnani C; et al. (2006). "D-dimer testing to determine the duration of anticoagulation therapy". N. Engl. J. Med. 355 (17): 1780–9. doi:10.1056/NEJMoa054444. PMID 17065639.
- ↑ Lee AY, Levine MN, Baker RI, Bowden C, Kakkar AK, Prins M, Rickles FR, Julian JA, Haley S, Kovacs MJ, Gent M (2003). "Low-molecular-weight heparin versus a coumarin for the prevention of recurrent venous thromboembolism in patients with cancer". N Engl J Med. 349 (2): 146–53. PMID 12853587.
- ↑ Agnelli G, Becattini C (2010). "Acute pulmonary embolism". N Engl J Med. 363 (3): 266–74. doi:10.1056/NEJMra0907731. PMID 20592294.