PULMONARY EMBOLISMPRESENTATION TO
DIAGNOSIS
ObjectivesReview the incidence, symptoms and
presenting signs of PELearn about clinical prediction modelsLearn about different diagnostic
methods and diagnostic algorithms.
IncidenceThe 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 populationMortality from PE is estimated to be
0.1%
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
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
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?
Clinical Decision Rules Models for assessing clinical
Probability of Pulmonary Embolism Well’s Criteria Geneva Score
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 1.5Immobilization (≥3 days) or surgery in the previous four weeks
1.5
Previous DVT/PE 1.5Hemoptysis 1.0Malignancy 1.0
Traditional clinical probability assessment (Wells criteria)
High >6.0Moderate 2.0 to 6.0Low <2.0
Simplified clinical probability assessment (Modified Wells criteria)
PE likely >4.0PE unlikely ≤4.0
Simplified Geneva Score
Variable ScoreAge >65 1Previous DVT or PE 1Surgery or fracture within 1 month 1Active malignancy 1Unilateral lower limb pain 1Hemoptysis 1Pain on deep vein palpation of lower limb and unilateral edema 1
Heart rate 75 to 94 bpm 1Heart rate greater than 94 bpm +1Score 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%
DIAGNOSTIC TESTS
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
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.
Chest RadiographyNot 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.
Radiographic Signs – Westermark Sign
Radiographic Signs – Hamptons Hump
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
CT ANGIOGRAPHY
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
CT Agiogram
Pulmonary Angiography
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
DIAGNOSTIC PATHWAYS
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.
Diagnostic Algorithm
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
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.
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
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