Pulmonary embolism 2

1. PULMONARY EMBOLISM

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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

5. Risk Factors
• Autoimmune diseases
• Air travel
• Thrombophillias
• In Women
– Obesity (BMI ≥29)
– Pregnancy
– Heavy cigarette smoking (>25 cigarettes per day)
– Hypertension

6. Presentation
 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 %)
Most Common Symptoms
Most Common Signs

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
3.0
Heart rate >100 1.5
Immobilization (≥3 days) or
surgery in the previous four weeks
1.5
Previous DVT/PE 1.5
Hemoptysis 1.0
Malignancy 1.0
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 1
Surgery or fracture within 1 month 1
Active malignancy 1
Unilateral lower limb pain 1
Hemoptysis 1
Pain on deep vein palpation of lower limb
and unilateral edema
1
Heart rate 75 to 94 bpm 1
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.
S1Q3T3

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. 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
Radiographic Signs
Westermark Sign

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

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. CTAgiogram
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

25. 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.

26. 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.

27. 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

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

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30. GOOD LUCK
SAMIR EL ANSARY
ICU PROFESSOR
AIN SHAMS
CAIRO
elansarysamir@yahoo.com