Pulmonary Embolism Presentation to Diagnosis

PULMONARY EMBOLISMPRESENTATION TO

DIAGNOSIS

Objectives

Review the incidence, symptoms and presenting signs of PE

Learn about clinical prediction modelsLearn about different diagnostic

methods and diagnostic algorithms.

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%

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 1.5

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

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%

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 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.

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 A

gio

gra

m

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