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| ==[[Pulmonary embolism natural history|Natural History, Complications & Prognosis]]== | | ==[[Pulmonary embolism natural history|Natural History, Complications & Prognosis]]== |
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| ==Diagnosis== | | ==[[Pulmonary embolism diagnosis|Diagnosis]]== |
| The diagnosis of PE is based primarily on the clinical evaluation combined with diagnostic modalities such as spiral CT, V/Q scan, use of the D-dimer and lower extremity ultrasound.
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| === Pretest Probability ===
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| In spite of all of nonspecific clinical and lab findings, it has been shown that clinicians are actually fairly good at assigning meaningful clinical probabilities for PE.
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| *In PIOPED, 67% of the patients labeled as having a high clinical probability (>80% likelihood) had PE, as compared with only 9% of those give a low clinical probability (<20% likelihood).
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| *Unfortunately, the majority of patients (64%) were assigned an intermediate clinical probability (20 – 80% likelihood), reinforcing the fact that a clinical diagnosis can be difficult.
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| ====High Pretest Probability====
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| Many authors, reserve the term high pretest probability for those patients with a clinical presentation consistent with PE, in whom an alternative diagnosis is not apparent (e.g. pneumonia) and who have known risk factors for venous thromboembolism (VTE).
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| ====Low Pretest Probability====
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| Low pretest probability patients include those patients with an alternative diagnosis to explain the clinical findings or those without risk factors.
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| ====Intermediate Pretest Probability====
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| Intermediate probability patients include those patients not fitting either high or low pretest probability definitions.
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| ===Predicting the Risk of Pulmonary Embolism===
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| The decision to do medical imaging is usually based on clinical grounds, i.e. the [[medical history]], symptoms and findings on [[physical examination]].
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| ;Development of the Wells score
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| The most commonly used method to predict clinical probability, the Wells score, is [[clinical prediction rule]], whose use is complicated by multiple versions being available. In 1995, Wells ''et al'' initially developed a prediction rule (based on a literature search) to predict the likelihood of PE, based on clinical criteria.<ref name="pmid7752753">{{cite journal |author=Wells PS, Hirsh J, Anderson DR, Lensing AW, Foster G, Kearon C, Weitz J, D'Ovidio R, Cogo A, Prandoni P |title=Accuracy of clinical assessment of deep-vein thrombosis |journal=Lancet |volume=345 |issue=8961 |pages=1326-30 |year=1995 |pmid=7752753 |doi=doi:10.1016/S0140-6736(95)92535-X}}</ref> The prediction rule was revised in 1998<ref name="pmid9867786">{{cite journal |author=Wells PS, Ginsberg JS, Anderson DR, Kearon C, Gent M, Turpie AG, Bormanis J, Weitz J, Chamberlain M, Bowie D, Barnes D, Hirsh J |title=Use of a clinical model for safe management of patients with suspected pulmonary embolism |journal=Ann Intern Med |volume=129 |issue=12 |pages=997-1005 |year=1998 |pmid=9867786}}</ref> This prediction rule was further revised when simplified during a validation by Wells ''et al'' in 2000.<ref name="pmid10744147">{{cite journal | author = Wells P, Anderson D, Rodger M, Ginsberg J, Kearon C, Gent M, Turpie A, Bormanis J, Weitz J, Chamberlain M, Bowie D, Barnes D, Hirsh J | title = Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer. | journal = Thromb Haemost | volume = 83 | issue = 3 | pages = 416-20 | year = 2000 | id = PMID 10744147}}</ref> In the 2000 publication, Wells proposed two different scoring systems using cutoffs or 2 or 4 with the same prediction rule.<ref name="pmid10744147"/> In 2001, Wells published results using the more conservative cutoff of 2 to create three categories.<ref name="pmid11453709">{{cite journal |author=Wells PS, Anderson DR, Rodger M, Stiell I, Dreyer JF, Barnes D, Forgie M, Kovacs G, Ward J, Kovacs MJ |title=Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer |journal=Ann Intern Med |volume=135 |issue=2 |pages=98-107 |year=2001 |pmid=11453709 | url=http://www.annals.org/cgi/content/full/135/2/98}}</ref> An additional version, the "modified extended version", using the more recent cutoff of 2 but including findings from Wells's initial studies<ref name="pmid7752753"/><ref name="pmid9867786"/> were proposed.<ref name="pmid10739372">{{cite journal |author=Sanson BJ, Lijmer JG, Mac Gillavry MR, Turkstra F, Prins MH, Büller HR |title=Comparison of a clinical probability estimate and two clinical models in patients with suspected pulmonary embolism. ANTELOPE-Study Group |journal=Thromb. Haemost. |volume=83 |issue=2 |pages=199-203 |year=2000 |pmid=10739372}}</ref> Most recently, a further study reverted to Wells's earlier use of a cutoff of 4 points<ref name="pmid10744147"/> to create only two categories.<ref name="pmid16403929">{{cite journal |author=van Belle A, Büller H, Huisman M, Huisman P, Kaasjager K, Kamphuisen P, Kramer M, Kruip M, Kwakkel-van Erp J, Leebeek F, Nijkeuter M, Prins M, Sohne M, Tick L |title=Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and computed tomography |journal=JAMA |volume=295 |issue=2 |pages=172-9 |year=2006 |pmid=16403929 | url=http://jama.ama-assn.org/cgi/content/full/295/2/172 | doi=10.1001/jama.295.2.172}}</ref>
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| There are additional prediction rules for PE, such as the Geneva rule. More importantly, the use of ''any'' rule is associated with reduction in recurrent thromboembolism.<ref name="pmid16461959">{{cite journal |author=Roy PM, Meyer G, Vielle B, Le Gall C, Verschuren F, Carpentier F, Leveau P, Furber A |title=Appropriateness of diagnostic management and outcomes of suspected pulmonary embolism |journal=Ann. Intern. Med. |volume=144 |issue=3 |pages=157-64 |year=2006 |pmid=16461959}}</ref>
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| ;Wells score
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| ''The Wells score'':<ref name="pmid12952389">{{cite journal |author=Neff MJ |title=ACEP releases clinical policy on evaluation and management of pulmonary embolism |journal=American family physician |volume=68 |issue=4 |pages=759-60 |year=2003 |pmid=12952389 |doi=|url=http://www.aafp.org/afp/20030815/practice.html}}</ref>
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| *clinically suspected [[DVT]] - 3.0 points
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| *alternative diagnosis is less likely than PE - 3.0 points
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| *tachycardia - 1.5 points
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| *immobilization/surgery in previous four weeks - 1.5 points
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| *history of DVT or PE - 1.5 points
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| *hemoptysis - 1.0 points
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| *malignancy (treatment for within 6 months, palliative) - 1.0 points
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| ;Interpretation of the Wells score
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| Traditional interpretation<ref name="pmid10744147"/><ref name="pmid11453709"/>
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| * Score >6.0 - High (probability 59% based on pooled data<ref name="pmid17185658">{{cite journal |author=Stein PD, Woodard PK, Weg JG, Wakefield TW, Tapson VF, Sostman HD, Sos TA, Quinn DA, Leeper KV, Hull RD, Hales CA, Gottschalk A, Goodman LR, Fowler SE, Buckley JD |title=Diagnostic pathways in acute pulmonary embolism: recommendations of the PIOPED II Investigators |journal=Radiology |volume=242 |issue=1 |pages=15-21 |year=2007 |doi=10.1148/radiol.2421060971 | pmid=17185658}}</ref>)
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| * Score 2.0 to 6.0 - Moderate (probability 29% based on pooled data<ref name="pmid17185658"/>)
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| * Score <2.0 - Low (probability 15% based on pooled data<ref name="pmid17185658"/>)
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| Alternate interpretation<ref name="pmid10744147"/><ref name="pmid16403929"/>
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| * Score > 4 - PE likely. Consider diagnostic imaging.
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| * Score 4 or less - PE unlikely. Consider [[D-dimer]] to rule out PE.
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| ==[[Pulmonary embolism differential diagnosis|Differential Diagnosis]]== | | ==[[Pulmonary embolism differential diagnosis|Differential Diagnosis]]== |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2], Ujjwal Rastogi, MBBS [3]
Combining tests into algorithms
Recent recommendations for a diagnostic algorithm have been published by the PIOPED investigators; however, these recommendations do not reflect research using 64 slice MDCT.[1] These investigators recommended:
- Low clinical probability. If negative D-dimer, PE is excluded. If positive D-dimer, obtain MDCT and based treatment on results.
- Moderate clinical probability. If negative D-dimer, PE is excluded. However, the authors were not concerned that a negative MDCT with negative D-dimer in this setting has an 5% probability of being false. Presumably, the 5% error rate will fall as 64 slice MDCT is more commonly used. If positive D-dimer, obtain MDCT and based treatment on results.
- High clinical probability. Proceed to MDCT. If positive, treat, if negative, addition tests are needed to exclude PE.
Predicting mortality
The PESI and Geneva prediction rules can estimate mortality and so may guide selection of patients who can be considered for outpatient therapy.[2]
Right ventricular dysfunction on echocardiography and higher than normal concentrations of troponin identify high risk patients who might need escalation of therapy with thrombolysis or embolectomy even if the blood pressure is normal on presentation.
References
- ↑ Invalid
<ref> tag; no text was provided for refs named pmid17185658
- ↑ Jiménez D, Yusen RD, Otero R; et al. (2007). "Prognostic models for selecting patients with acute pulmonary embolism for initial outpatient therapy". Chest. 132 (1): 24–30. doi:10.1378/chest.06-2921. PMID 17625081.
Sources
- Bertucci, V., Asch, M.R., Balter, M., Prognosis in a patient with an initial normal pulmonary angiogram, Chest 1994; 105: 1257-1258.
- Cvitanic, O, Marino, P.L., Improved use of arterial blood gas analysis in suspected pulmonary embolism, Chest 1989; 95: 48-51.
- Drucker, E.A., et.al., Acute pulmonary embolism: assessment of helical CT for diagnosis, Radiology 1998; 209: 235-241.
- Ferrari, E., et.al., The ECG in pulmonary embolism: predictive value of negative T waves in precordial leads – 80 case reports, Chest 1997; 111: 537-543.
- Goldhaber, S.Z., et.al., Quantitative plasma D-dimer levels among patients undergoing pulmonary angiography for suspected pulmonary embolism, JAMA 1993; 270: 2819-2822.
- Goldhaber, S.Z., Pulmonary embolism, NEJM 1998; 339: 93-104.
- Mayo, J.R., et.al., Pulmonary embolism: prospective comparison of spiral CT with ventilation-perfusion scintigraphy, Radiology 1997; 205: 447-452.
- Meaney, J.F.M., et.al., Diagnosis of pulmonary embolism with magnetic resonance angiography, NEJM 1997; 336: 1422-1427.
- The PIOPED investigators, Value of the ventilation / perfusion scan in acute pulmonary embolism: results of the prospective investigation of pulmonary embolism diagnosis (PIOPED), JAMA 1990; 263: 2753-2759.
- Remy-Jardin, M., et.al., Diagnosis of pulmonary embolism with spiral CT: comparison with pulmonary angiography and scintigraphy, Radiology 1996; 200: 6999-706.
- Stein, P.D., et.al., Clinical, laboratory, roentgenographic, and electrocardiographic findings in patients with acute pulmonary embolism and no pre-existing cardiac or pulmonary disease, Chest 1991; 100: 598-603.
- Stein, P.D., et.al., Arterial blood gas analysis in the assessment of suspected pulmonary embolism, Chest 1996; 109: 78-81.
- Thompson, B.T., Hales, C.A., Diagnostic strategies for acute pulmonary embolism, in UpToDate, September 10, 1998.
- Van Erkel, A.R., et.al., Spiral CT angiography for suspected pulmonary embolism: a cost-effective analysis, Radiology 1996; 201: 29-36.
Acknowledgements
The content on this page was first contributed by: Editor-In-Chief: C. Michael Gibson, M.S., M.D. [4] and David Feller-Kopman, M.D.
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