Pulmonary Embolism
Pulmonary Embolism
– Thrombotic
– Nonthrombotic
• Fat Embolism
• Amniotic Fluid Embolism
• IVDA (Talc, cotton, etc)
• Venous thromboembolism (VTE), which
encompasses deep venous thrombosis
(DVT) and pulmonary embolism (PE), is
one of the three major cardiovascular causes
of death, along with myocardial infarction
and stroke.
• PE is the most common preventable cause
of death among hospitalized patients
• Approximately three of four symptomatic
VTE events occur in the community, and
the remainder are hospital acquired
• In the United States, the Surgeon General
• estimates there are 100,000 to 180,000
deaths annually from PE
• Approximately 14 million (M) hospitalized
patients are at moderate to high risk for
VTE in the United States annually: 6 M
major surgery patients and 8 M medical
patients with comorbidities such as heart
failure, cancer, and stroke.
• The long-term effects of nonfatal VTE
lower the quality of life. Chronic
thromboembolic pulmonary hypertension is
often disabling and causes breathlessness. A
late effect of DVT is postphlebitic
syndrome, which eventually occurs in more
than one-half of DVT patients
PE
• Epidemiology
– Five million cases of venous thrombosis each
year
– 10% of these will have a PE
– 10% will die
– Correct diagnosis is made in only 10-30% of
cases
– Up to 60% of autopsies will show some
evidence of past PE
PE
– 90-95% of pulmonary emboli originate in the
deep venous system of the lower extremities
– Other rare locations include
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Uterine and prostatic veins
Upper extremities
Renal veins
Right side of the heart
Virchow’s Triad
• Rudolf Virchow postulated more than a
century ago that a triad of factors
predisposed to venous thrombosis
– Local trauma to the vessel wall
– Hypercoagulability
– Stasis of blood flow
• It is now felt that pts who suffer a PE have
an underlying predisposition that remains
silent until a acquired stressor occurs
predisposing factors
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cancer
obesity
cigarette smoking,
hypertension
COPD
Surgery and trauma
chronic kidney disease
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blood transfusion,
long-haul air travel ,
air pollution,
oral contraceptives,
pregnancy ,
• postmenopausal
hormone replacement,
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Factor V Leiden mutation
Prothrombin gene mutation A20210
Protein C deficiency
Protein S deficiency
Antithrombin deficiency
Anticardiolipin antibodies
Lupus anticoagulant
Factor V Leiden
• Most frequent inherited predisposition to
hypercoagulability
• Resistance to activated Protein C
• Single point mutation (Factor V Leiden)
• Single nucleotide substitution of glutamine for
arginine
• Frequency is about 3% in healthy American male
physicians participating in the Physicians’ Health
Study
PE
• When venous emboli become dislodged
from their site of origin, they embolize to
the pulmonary arterial circulation or,
paradoxically to the arterial circulation
through a patent foramen ovale
– About 50% of pts with pelvic or proximal leg
deep venous thrombosis have PE
– Isolated calf or upper extremity venous
thrombosis pose a lower risk for PE
Pathophysiology
• Increased pulmonary vascular resistance
• Impaired gas exchange
– increased alveolar dead space from vascular
obstruction,
– hypoxemia from alveolar hypoventilation relative to
perfusion in the nonobstructed lung, right-to-left
shunting, or impaired carbon monoxide transfer due to
loss of gas exchange surface.
• Alveolar hyperventilation
• Increased airway resistance
• Decreased pulmonary compliance
Clinical Syndromes
• Pts with massive PE present with systemic
arterial hypotension and evidence of
dyspnea, syncope, hypotension, and
cyanosis
• Pts with moderate PE will have right
ventricular hypokinesis on echocardiogram
but normal systemic arterial pressure
• Pts with low risk PE have both normal right
heart function and normal systemic arterial
pressure
• Clinical Syndromes
– Pulmonary Infarction usually indicates a small
PE, but is very painful, because it lodges near
the innervation of the pleural nerves
Diagnosis
• H&P
• Always ask about prior DVT, or PE
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Family History of thromboembolism
Dyspnea is the most frequent symptom of PE
Tachypnea is the most frequent physical finding
Dyspnea, syncope, hypotension, or cyanosis
suggest a massive PE
– Pleuritic CP, cough, or hemoptysis
Symptom list
 73% Dyspnea
 66% Pleuritc Pain
 43% Cough
 33% Leg Swelling
 30% Leg Pain
 15% Hemoptysis
 12% Palpitations
 10% Wheezing
 5% Angina-Like pain
Common symptoms
Common physical signs
Cyanosis 19%
Cardiac murmur 23%
Thrombophlebitis 32%
S3 OR S4 34%
Fever 43%
Tachycardia 44%
Rales 58%
Tachypnea 92%
Physical Signs & Symptoms
 Dyspnea 73%
 Pleuritc Pain 66%
 Cough 43%
 Leg Swelling 33%
 Leg Pain 30%
 Hemoptysis 15%
 Palpitations 12%
 Wheezing 10%
 Angina-Like pain 5%
Differential Diagnosis
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PE is known as “the great masquerader”
Unstable angina , MI
Pneumonia, bronchitis
CHF
Asthma
Costochondritis , Rib Fx,
Pneumothorax
PE can coexist with other illnesses!!
A Summary so Far…
• History alone is unreliable
• Physical exam is close to useless
• However, studies have shown that our
clinical suspicion of PE is useful in
interpreting diagnostic tests
WELLS CRITERIA
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Suspected DVT
3
An alternative diagnosis is less likely than PE 3
Heart rate > 100 beats / min
1.5
Immobilization or surgery in pervious 4 week 1.5
Pervious DVT / PE
1.5
Hemoptysis
1
Malignancy(on treatment or treated in past 6 1
months )
• Low clinical Likelihood of DVT if Point
Score Is Zero or Less;
• Moderate Likelihood if Score Is 1 to 2;
• High Likelihood if Score Is 3 or Greater
Estimation of Pretest Clinical Probability of Pulmonary Embolism
Pretest Clinical Probability Clinical Findings
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Low-probability
(unlikely)1. Symptoms incompatible with pulmonary embolism or compatible
symptoms (see below; high-probability section) that can be explained by an
alternative process, such as pneumonia, pneumothorax, or pulmonary edema
2. No radiographic or electrocardiographic abnormalities compatible with
pulmonary embolism, or findings that can be explained by an alternative
diagnosis
3. Absence of risk factors for venous thromboembolism
Intermediate-probability
(possible/probable)1. Symptoms compatible with pulmonary embolism, but no
associated radiographic or electrocardiographic findings
2. Constellation of findings not consistent with low or high clinical probability
High-probability
(very likely)1. Symptoms compatible with pulmonary embolism (sudden-onset
dyspnea, pleuritic chest pain, tachypnea, or syncope), not explained otherwise
2. Radiographic or electrocardiographic findings compatible with pulmonary
embolism, or widened alveolar-arterial oxygen gradient, not explained
otherwise
3. Presence of risk factors for venous thromboembolism
Diagnosis
• Serum Studies
– D-dimer
• Elevated in more than 90% of pts with PE
• Reflects breakdown of plasmin and endogenous thrombolysis
• Not specific: Can also be elevated in MI, sepsis, or almost any
systemic illness
• Negative predictive value
– ABG-contrary to classic teaching, arterial blood gases
lack diagnostic utility for PE
A-a Gradient
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Alveolar arterial oxygen gradient
148-1.2(PaCO2) - PaO2
Gradient > 15-20 is considered abnormal.
Done at Room air.
Diagnosis
• CXR
– Usually reveals a non specific abnormality.
14% normal
– Classic abnormalities include:
• Westermark’s Sign - focal oligemia
• Hampton’s Hump - wedge shaped density
• Enlarged Right Descending Pulmonary Artery
(Palla’s sign)
Hamptons
Hump
PE
Westermark’s Sign
PE
PE which
appears like
a mass.
PE with hemorrhage
or pulmonary edema
PE with effusion
and elevated diaphragm
Venous Ultrasonography
• Relies on loss of vein compressibility as the
primary criterion
• About 1/3 of pts will have no imaging
evidence of DVT
• Clot may have already embolized
• Clot present in the pelvic veins (U/S usually
inadequate)
– Workup for PE should continue even if
dopplers (-) in a pt in which you have a high
clinical suspicion
V/Q Scan
• Historically, the principal imaging test for
the diagnosis of PE
– A perfusion defect indicates absent or
decreased blood flow
– Ventilation scan obtained with radiolabeled
gases
– A high probability scan is defined as two or
more segmental perfusion defects in presence
of nl ventilation scan
V/Q Scan
• Useful if the results are normal or near
normal, or if there is a high probability for
PE
– As many as 40% of pts with high clinical
suspicion for PE and low probability scans have
a PE on angiogram
High Probability V/Q Scan
Pulmonary Angiogram
• Most specific test available for diagnosis of
PE
• Can detect emboli as small as 1-2 mm
• Most useful when the clinical likelihood of
PE differs substantially from the lung scan
result or when the lung scan is intermediate
probability
Echocardiogram
– Useful for rapid triage of pts
– Assess right and left ventricular function
– Diagnostic of PE if hemodynamics by echo are
consitent with clinical hx
Spiral CT Scan
• Identifies proximal PE (which are the ones
usually hemodynamically important)
• Not as accurate with peripheral PE
CT revealing pulmonary infarct
DIAGNOSIS OF VENOUS
THROMBOEMBOLISM
Spiral chest CT scan
DIAGNOSIS OF VENOUS
THROMBOEMBOLISM
Spiral chest CT scan
Treatment
• Begin treatment with either unfractionated
heparin or LMWH, then switch to warfarin
(Prevents additional thrombus formation and permits endogenous
fibrinolytic mechanisms to lyse clot that has already been formed,
Does NOT directly dissolve thrombus that already exists)
• Warfarin for atleast 3 months, INR 2-3
Treatment
• Pain Relief
• Supplemental Oxygen
• Dobutamine for pts with right heart failure
and cardiogenic shock
• Volume loading is not advised because
increased right ventricular dilation can lead
to further reductions in left ventricular
outflow
Treatment
• Thrombolysis
1. Hemodynamically compromised by PE – definitie
indication
2. Pulmonary hypertension or right ventricular dysfunction
detected by echocardiography, pulmonary arterial
catheterization, or new electrocardiographic evidence of
right heart stain. (controversial)
• Embolectomy
– Reserved for pts at high risk for death and those at risk
for recurrent PE despite adequate anticoagulation,
contraindication for thrombolytics
Adjunctive Therapy
• Duration of Anticoagulation
– Dependent upon the clinical situation
• Cancer, and Obesity most likely will need indefinite
treatment
• For other pts with isolated calf vein thrombosis (3
mos), proximal leg DVT (6 mos) and PE (1 year)
• Inferior Vena Caval Filter
• When anticoagulation cannot be undertaken
• Recurrent thrombosis despite anticoagulation
Conclusion
• PE is often a misdiagnosed clinical disorder.
• Rapid identification and appropriate
treatment may often prevent unnecessary
morbidity and mortality.
• The two principal indications for insertion
of an IVC filter are
• (1) active bleeding that precludes
anticoagulation
• (2) recurrent
• venous thrombosis despite intensive
anticoagulation