1. Pulmonary Embolism Presentation to Diagnosis

2. Objectives Review the incidence, symptoms and presenting signs of PE
Learn about clinical prediction models
Learn about different diagnostic methods and diagnostic algorithms.

3. Incidence
The true incidence of PE is unknown and is suspected to be underestimated
It is estimated to be between 0.5% to 3% in the general population
Mortality from PE is estimated to be 0.1%

4. Risk Factors Previous or current DVT Immobilization
Surgery within the last 3 months
Stroke/paralysis
Central venous instrumentation within the last 3 months
Malignancy
CHF
Autoimmune diseases
Air travel *
Thrombophillias
In Women
Obesity (BMI ≥29)
Pregnancy
Heavy cigarette smoking (>25 cigarettes per day)
Hypertension
* Optional Info:
Air travel for > 4 hours doubles your risk for a venous thromboembolism
Most of these patients had an undiagnosed underlying thrombophillia such as Factor V Leiden or other risk factor
Incidence in healthy individuals of VTE due to air travel is 1:6000

5. Presentation Most Common Symptoms Most Common Signs Tachypnea (54 %)
Dyspnea at rest or with exertion (73 %)
Pleuritic pain (44 %)
Cough (34 %)
>2-pillow orthopnea (28 %)
Calf or thigh pain (44 %)
Calf or thigh swelling (41 %),
Wheezing (21 %)
Rapid onset of dyspnea
within seconds (46 %)
within minutes (26 %)
Tachypnea (54 %)
Tachycardia (24 %)
Rales (18 %),
Decreased breath sounds (17 %),
Accentuated pulmonic component of the second heart sound (15 %)
Jugular venous distension (14 %)

6. Case
A 63-year-old woman with stage IV lymphoma calls 911 for acute shortness of breath (SOB). At baseline, the patient is mobile and does not have SOB. She is also taking hormone replacement therapy. On the day of admission, she develops a sudden SOB and new pleuritic chest pain. She does not improve with nebulizer treatment on the way to the hospital. In the ER, her pulse is 115 bpm, RR = 36/min, temp = 100.1oF and O2 sat = 88% on room air. On exam, her lungs are clear, and her extremities are normal. A chest x-ray (CXR) shows mild right-sided atelectasis. An ABG shows ph = 7.48, PCO2 = 32 mm Hg and PO2 = 50 mm Hg on room air.
What is this patient’s pretest probability for having a pulmonary embolism?
What diagnostic method would you use to confirm this?
Patient presenting with classic symptoms, signs and risk factors of possible PE. These are the questions we will be addressing during this talk, and by the end we will review the answers.

7. Clinical Decision Rules
Models for assessing clinical Probability of Pulmonary Embolism
Well’s Criteria
Geneva Score

8. Wells’ Score
Clinical symptoms of DVT (leg swelling, pain with palpation)
3.0
Other diagnosis less likely than pulmonary embolism
Heart rate >100
1.5
Immobilization (≥3 days) or surgery in the previous four weeks
Previous DVT/PE
Hemoptysis
1.0
Malignancy
Traditional clinical probability assessment (Wells criteria)
High
>6.0
Moderate
2.0 to 6.0
Low
<2.0
Simplified clinical probability assessment (Modified Wells criteria)
PE likely
>4.0
PE unlikely
≤4.0

9. Simplified Geneva Score
Variable
Score
Age >65 1
Previous DVT or PE
Surgery or fracture within 1 month
Active malignancy
Unilateral lower limb pain
Hemoptysis
Pain on deep vein palpation of lower limb and unilateral edema
Heart rate 75 to 94 bpm
Heart rate greater than 94 bpm +1
Score of less than 2 is low probablility for PE, score of less than 2 plus a negative D-dimer results in a likelihood of PE of 3%

10. Diagnostic tests

11. D-Dimer
Elevated in thrombosis, malignancy, pregnancy, elderly, hospitalized patients
Role in low or moderate probability for PE
Normal results can rule out PE
Estimated 3 month risk of thromboembolism with negative D-dimer is 0.14%
Role in high probability patients  proceed to CT, negative d-dimer can miss up to 15% of patients in this group

12. EKG in Pulmonary Embolism
Most commonly sinus tachycardia, with possible nonspecific ST/T wave changes
Only 10% of patients can have the S1Q3T3 so not reliable
Other EKG abnormalities including atrial arrhythmias, right bundle branch block, inferior Q-waves, and precordial T-wave inversion and ST-segment changes, are associated with a poor prognosis.

13. Chest Radiography
Not a sensitive or specific test for the diagnosis of PE.
Atelectasis, Pleural effusion, or a pulmonary parenchymal abnormality is noted most commonly
Only a small portion of patients with PE have a normal CXR.

14. Radiographic Signs – Westermark Sign
The sign results from a combination of:
dilation of the pulmonary arteries proximal to the embolus
collapse of the distal vasculature creating the appearance of a sharp cut off on chest radiography
The Westermark sign has a low sensitivity (11%) and high specificity (92%) for the diagnosis of pulmonary embolus

15. Radiographic Signs – Hamptons Hump
Wedge-shaped infarct
sensitivity (21) and specificity (82%) for the diagnosis of pulmonary embolus

16. Ventilation-Perfusion Scans
Useful if Normal (negative predictive value of 97%)
Also useful if High probability (positive predictive value of 85 to 90%)
Unfortunately, only diagnostic in 30 to 50% of patients
Optional Info:
PIOPED I looked at the accuracy of diagnosing PE compared with gold standard of pulmonary angiography
Normal V/Q scan and high probability V/Q scans were helpful in ruling out or in PE but indeterminate category required additional testing
Venous ultrasonography can diagnose thromboembolism in 4% of patients with a non-diagnostic V/Q scan

17. CT Angiography

18. CT Angiography
Studies have shown sensitivity of close to 95% with an experienced observer
One of the most commonly cited benefits of CTA is its ability to detect alternative pulmonary abnormalities that may explain the patient's symptoms and signs
In 67% of patients without PE, CT provided additional information for alternate diagnosis
May predispose patients to further unnecessary testing

19. CT Agiogram
Acute pulmonary embolism and deep venous thrombosis (DVT) in a 48-year-old woman. Multifocal low-attenuation emboli (arrows) in segmental and subsegmental arteries in the right lower lobe. 

20. Pulmonary Angiography

21. Pulmonary Angiography in PE
The “gold standard”
A negative pulmonary angiogram excludes clinically relevant PE.
The risk of embolization in patients with a negative angiogram is extremely low 

22. Diagnostic Pathways

23. Is it important to use clinical decision rules?
In the setting of no thromboembolic risk factors, it is extraordinarily unlikely (0.95% chance) to have a CT angiogram positive for PE.
With the combination of a negative D- dimer test result, this risk is even lower.

24. Diagnostic Algorithm
When PE is suspected, the modified Wells criteria should be applied to determine if PE is unlikely (score ≤4) or likely (score >4). The modified Wells Criteria include the following:
Patients classified as PE unlikely should undergo D-dimer testing with a quantitative rapid ELISA assay or a semiquantitative latex agglutination assay. The diagnosis of PE can be excluded if the D-dimer level is <500 ng/mL or negative.
Patients classified as PE likely and patients classified as PE unlikely who have a D-dimer level >500 ng/mL should undergo CT-PA. A positive CT-PA confirms the diagnosis of PE. Alternatively, a negative CT-PA excludes the diagnosis of PE.
In those rare instances in which the CT-PA is inconclusive, either pulmonary angiography or the diagnostic approach intended for institutions without experience in CT-PA can be used.

25. Lower Extremity US indicated?
Depends on pre-test probability
High pretest probablity for PE and negative CT may require additional testing
Good initial test to evaluate for pulmonary embolism in patients with contrast allergy, renal insufficiency, pregnancy, or critically ill patients.
Inexpensive test without radiation exposure
Can avoid additional testing if positive

26. Case Presentation Reminder:
A 63-year-old woman with stage IV lymphoma with acute shortness of breath (SOB) and pleuritic chest pain. At baseline, the patient is mobile and does not have SOB. She is also taking hormone replacement therapy. In the ER, her pulse is 115 bpm. On exam, her lungs are clear, and her extremities are normal. A chest x-ray (CXR) shows mild right-sided atelectasis. An ABG shows ph = 7.48, PCO2 = 32 mm Hg and PO2 = 50 mm Hg on room air.

27. Case Presentation
Applying the Wells’ Scoring system, the patient has a moderate likelihood of having a PE with a score of 5.5 for high clinical suspicion for PE, tachycardia, and cancer.
Considering the patient’s score is >4, may proceed to CT angiography for PE rule out.
This patient did have CTA performed, which confirmed presence of PE.
She was subsequently started on anticoagulation

28. Summary and Recommendations
Consider your patient’s risk factors for pulmonary embolism
The clinical presentation of acute pulmonary embolism is variable and nonspecific
The major diagnostic tests employed in the evaluation of a patient with suspected PE include d-dimer testing, CTPA, V/Q scanning, venous ultrasonography, and conventional pulmonary angiography
Follow a diagnostic algorithm that combines CTPA, d-dimer and clinical assessment