Pulmonary Embolism:
Saving your Patient, your Rand and making
sense of the “clot” !
Dr Sa’ad Lahri
Emergency Medicine Registrar
Outline and Objectives
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Clinical Presentation
Lab Tests and the ECG in PE
Risk Stratification
PE in Pregnancy
Do you understand your Imaging?
Treatment
Protective documentation
Take Home Points
Background
Background
• More than 600,000 cases / It’s common
yr
and 60,000 – 100,000
deaths / yr
We miss it
• 70% diagnosed at autopsy
25 - 35% = Mortality if
It kills you
untreated
2 - 8% = Mortality if treated
Carson, NEJM, 92
Detecting it
makes a
difference
N Engl J Med 2008;358:1037-52
Pathophysiology
Is the
presentation“boring?”
“boring” ?
Is clinical
the Presentation
• Movie …
Video.mp4
Clinical Presentation
• Classic teaching:
• Dyspnoea,tachycardic, tachypnoeic, and
has pleuritic pain
 Acute PE - Spectrum that ranges from:
 Clinically unimportant / incidental
Haemoptysis
 Minor emboli ± infarction
Pleuritic pain
Pulmonary signs
 Large pulmonary emboli
Dyspnoea
Ischaemic pain
 Massive emboli
/Cardiac
Collapse
Clinical Presentation
Signs
Symptoms
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Dyspnoea 73%
Pleuritic pain 66%
Cough 37%
Leg Swelling 28%
Leg Pain 26%
Haemoptysis 13%
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RR>20
70%
Rales
51%
Tachycardia 30%
Loud P2
23%
Temp>38.5 C 7%
Wheezes
Stein, Chest 1991 & Miniati Am J5%
Resp CC 1999
Clinical Presentation
Signs
Symptoms
• Dyspnoea 73%
vs
59%
• Pleuritic pain 66%vs
43%
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• RR>20
70% vs
68%
• Rales
51%
• Tachycardia 30%vs
Cough 37% vs 25%
23%
Leg Swelling 28%
• Loud P2
23%
Leg Pain
26%
Stein, Chest 1991 & Miniati Am
Resp CC 1999
• JTemp>38.5
7%vs
Haemoptysis 13%
17%
Signs/Symptoms Pearls
• Dyspneoa, Tachypneoa, or Pleuritic CP – the
Triggers!
• History and Physical Exam
– Ask about recent travel, surgery, or leg swelling
– O2 Sat & Respiratory Rate - Measure yourself
– Examine and even measure the extremities
(> 3cm asymmetry 10 cm below tibial tuberosity)
• Don’t make an alternate diagnosis by
misinterpreting non-specific findings
– (ex. Partially reproducible pain =>
Costochondritis)
Risk factors for PE
Risk factors for PE
• Acute Medical Illness
• CHF/COAD presentation
not recognised / similar
• Obesity -
under recognised
Risk Risk
Factors
- Pearls
factor Pearls
• Risk Factors increase your suspicion
• However 20% of patients with PE have no
known Risk Factors
• Therefore Lack of Risk Factors by no
means excludes PE
Risk Stratification
• Clinical Gestalt
• Clinical Algorithms – Wells/ Wicki/ Kline/
Miniati
• Hard to remember … memorise??
• Do not agree on any single finding that is
predictive of PE
Clinical Gestalt
Clinical Gestalt + Clinical decicion rule
Using D – Dimer in low risk
Excellent outcomes
Clinical Gestalt: Works Just as well
Runyon et al., Acad EM, 2005
• The unstructured clinical estimate of low
pretest probability for PE compares
favorably with the Canadian score and the
Charlotte rule.
• Interobserver agreement for the
unstructured estimate is moderate.
Clinical Algorithms
We Don’t Remember Them!!!!!
Runyon et al., Acad EM, 2007
• Half of all clinicians reporting familiarity with
the rules use them in more than 50% of
applicable cases.
• Spontaneous recall of the specific elements
of the rules was low to moderate.
Risk Stratification Pearls
• Gestalt appears equivalent to
Algorithms
• Algorithms may be beneficial for
trainees
• Algorithms may be beneficial for
institutional uniformity
Some Essential Stats
SpPin: with high Specificity, a
Positive result tends to rule in
SnNout: with high Sensitivity, a
Negative result tends to rule
out
D Dimer and PE
D Dimer and PE
• Quantitative D Dimer (Elisa)
+>0.5mg/l , -ve <0.25mg/l
• High sensitivity (>96%)
• Low specificity (AMI, pneumonia,
dissection, sepsis)
• High negative predictive value (99%)
D Dimers continued…
• NHLS have D Dimer Latex reagent
(agglutination assay)
• Latex kits demonstrate inadequate
sensitivity to
• reliably exclude PE in multiple studies
(pooled sensitivity=70% and
specificity=76%
• Positive samples … semi Quantitative
method
• Private Labs?
D Dimer and PE
 Combing Clinical Probability & D-Dimer
ð Christopher Study1 (n = 3,306)
ð Dichotomized Wells score ≤ 4
ð D-Dimer ≤ 500 ng/ml
ð Negative predictive value > 99.5%
ð Useful in excluding PE in outpatients
ð Safe to withhold treatment
1. Van Belle A, et al. Effectiveness of Managing Suspected Pulmonary Embolism
Using an Algorithm Combining Clinical Probability, D-Dimer Testing, and
Computed Tomography. JAMA 2006;295(2):172-179
D Dimer and PE
 Combing Clinical Probability & D-Dimer
ð Patients with high probability1 (n = 1,722)
ð Dichotomized Wells score > 4
ð D-Dimer ≤ 500 ng/ml
ð VTE confirmed in 9.3% !
ð VTE in 1.1% with low probability
(p<0.001)
1. Gibson NS, et al. The Importance of the Clinical Probability Assessment in
Interpreting a Normal D-Dimer in Patients with Suspected Pulmonary Embolism.
Chest 2008;134:789-793
Conclusion on D-Dimers
IF your patient has low pretest
probability for venous
thromboembolic disease, and…
IF you use an ELISA, rapid ELISA,
turbidimetric, or erythrocyte
agglutination D-dimer test…
Conclusion on D-Dimers
…THEN you can drive your false
negative rate to below 2% and
safely rule out pulmonary
embolism
Conclusion on D-Dimers
IF pretest probability is high, then
NO D-dimer can safely rule out
VTE
D-dimer is NOT a “screening test.”
It is a diagnostic test to “Rule out”
in appropriate patients
 Modified Wells score1 (“dichotomised”)
≤ 4 PE
Score
> 4 PE
1.
Wells PS, Anderson DR, Rodger M, et al. Derivation of a simple clinical model to
categorize patients’ probability of pulmonary embolism: increasing the model’s
utility with the SimpliRED D-dimer. Thromb Haemost. 2000;83:416-420.
“unlikely”
“likely”
PE?
Clinical Probability: Wells Score
≤4
>4
D-Dimer
≤ 0.5
> 0.5
Pulmonary Embolism excluded
Imaging, e.g. CTPA
PERC Rule
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8138 – suspected PE
2/3 Low suspicion
20% low suspicion and met PERC rule
Sensitivity 97.4% Specificity 21.9%
PERC rule takes a low probability subgroup
of patients and makes the risk even lower
• The combination of gestalt estimate of low
suspicion for PE andKlinePERC
reduces the
et al J Thromb Haemost 2008; 6: 772–80.
probability of VTE to below 2%
PERC Rule
Cardiac Biomarkers and PE
B-type natriuretic
peptide
Cardiac troponin
• elevated in congestive
• not sensitive as a
heart failure/Pulm Hypt
diagnostic tool
• negative predictive value
• significantly associated
Those with positive BNP and troponin
for an uneventful
withtesting
RV dysfunction on
be considered for ECHO assessment of RV
outcomeshould
of
99%.
ECHO &complicated in
function
hospital course and
mortality
Utility of CXR?
• Clinical Bottom Line
• Alone little value in diagnosis
• Value is in ruling out
other causes or as
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part of a risk stratification strategy
Hampton’s
Hump
CXR in Pulmonary Embolism
• Atelectasis and/or pulmonary parenchymal
abnormalities were most common, 79 of
Stein PD - Chest - 01-SEP-1991; 100(3): 598-603
117 (68 percent)
• cardiac enlargement (27% ), normal (24%
), pleural effusion (23% ), elevated
hemidiaphragm (20% ), pulmonary artery
enlargement (19% ), atelectasis (18% ),
Chest - Volume 118, Issue 1 (July 2000)
and parenchymal pulmonary infiltrates
(17%)
ECG in Pulmonary Embolism
• T-wave inversions, especially in right
precordial leads (V1-V3) + inferior leads
• S 1Q3T3 pattern in acute cor pulmonale
(12%).
Poor sensitivity
• Right axis deviation, transient right bundle
branch block (RBBB),
Cannot be
• Arrhythmias (sinus tachycardia, atrial flutter,
alone!
atrial fibrillation, used
atrial tachycardia,
and atrial
premature contractions)
• Normal
• The most common abnormalities are
nonspecific ST segment-T wave changes with
sinus tachycardia, unfortunately, these findings
ECG in Pulmonary Embolism
• Classic “SIQ3T3 pattern”
• Mistakenly considered pathognomonic for
acute PE by many clinicians
• Seen less frequently--15% to 25% of
patients ultimately diagnosed with PE will
have this pattern
Panos R J, Barish RA, Depriest WW, et al: The Electrocardiographic
manifestations of pulmonary embolism. J Emerg Med 1988; 6:301-7
ECG in Pulmonary Embolism
ECG in Pulmonary Embolism
• T wave Inversions in anteroseptal and
inferior leads
• Highly specific for PE (99%)
• Kosuge (Am J Cardiology 2007)
Chest Pain Tunnel Vision
ECG in Pulmonary Embolism
• PE often causes ECG changes that
resemble cardiac ischemia
• Don’t just “rule out MI” when the ECG
appears to show cardiac ischemia
ABG?
• The PO2 on arterial blood gases analysis (ABG) has a
zero or even negative predictive value in a typical
population of patients in whom PE is suspected clinically
• Other diseases that may masquerade as PE (eg,
[COPD, pneumonia, CHF) affect oxygen exchange > PE
• High incidence of PE and a lower incidence of other
respiratory ailments (eg, postoperative orthopedic
patients with sudden onset of shortness of breath), a low
PO2 has a strongly positive predictive value for PE.
• Use it in conjunction with other tests
Imaging studies
CTPA
V/Q
Ventilation Perfusion Scanning
Advantages
• Low complication
rate
• Moderate radiation
exposure
• Can be used in
renal dysfunction
Disadvantages
• Far away
• Majority non
diagnostic – add
testing
• Major abn on CXR –
(collapse/P effusions)
indeterminate scan
V/Q Scan
High Probablity
PE Diagnosed
Normal
Excludes PE
Low/
Intermediate
Debate!
Low risk and low probability
D/C
Intermediate and D Dimer
neg ? No or
additional/CTPA +u/s
N Engl J Med 2008;358:1037-52.
CTPA
• Preferable to V/Q in patients with prexisting lung
disease
• Specificity (93-99%) Sensitivity (85%)
• Combined with CTV – Sensitivity (90%)
• Other causes of chest pain imaged/found
• CTV using dye from CTPA image venous system
• Renal dysfunction/contrast allergies … Problem
• Radiation dosing high … !!!
N Engl J Med 2008;358:1037-52.
Echocardiography
• Rapid and accurate – PE instability
• Exclude other causes of hypotension and
raised JVP
• Can be performed in resus room and
guide thromobolytic therapy for unstable
patient
N Engl J Med 2008;358:1037-52.
Pulmonary Embolism & Pregnancy
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Low-dose oral contraceptives/HRT risk increases
PE risk increased all trimesters
D Dimers ? Consider use/ Levels increased
Do ultrasound of lower limbs
If CT scanning use lead shielding
Thromboytic therapy not withheld Life threatening
PE
• Long term anticoagulation : LMWH
• Warfarin Teratogen
Management: Adjuvant therapy
Adjuvant
therapy
Resp Failure
Oxygen
Mechanical
Ventilation
RV
Dysfunction
Fluids
(cautious)
Inotropes
(Dobutamine)
N Engl J Med 2008;358:1037-52.
Treatment: Anticoagulation
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LMWH
Need to monitor in patients with
Weight <40kg or >150kg
Pregnant
Renal Impairment
Measure level of activity against factor Xa
N Engl J Med 2008;358:1037-52.
Treatment: Anticoagulation
• Not thrombolytic – fibrinolytic system to x
unopposed
• Decrease thromboembolic burden
• LMWH vs unfractionated heparin
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LMWH = Un Heparin tx PE
Greater bioavailablity
Ease admin, no monitoring of INR …
Lower risk of HIT
Treatment
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Thrombolytic therapy- Background
Faster clot lysis
May reverse RV failure
Decrease risk recurrence
Risk: Major haemorrhage 1.8-6.3%
ICH : 1.2 %
Fibrinolytic Therapy in PE
Cardic Arrest?
Clear BenefitRisk Ratio
NO Absolute
contraindications
Prolonged CPR
not CI
Fibrinolytic Therapy in PE
• Clear benefit in Cardiac Arrest and
haemodynamically unstable due to PE
• No benefit in stable patients with normal RV function
• Stable but RV dysfunction on echo – “may improve
mortality” … jury is still out… Current evidence not
there
Loebinger et al, QJ med
2004;97:361-364
• Hypoxaemia? Subgroup worse prognosis,
may
necessitate need for thrombolysis
Fibrinolytic Therapy in PE
Fibrinolytic Therapy in PE
• Tenecteplase, may have higher efficacy than
alteplase due to its bolus dosing, longer halflife, higher fibrin specificity, and more rapid
fibrinolytic capacity
• In cardiac arrest suspected to be caused by
PE, the immediate use of a 50-mg alteplase
bolus “may be lifesaving”
• Streptokinase (250,000 U bolus, followed by
100,000 U/h for 24 hours) approved by FDA
[Ann Emerg Med. 2003;41:257-270.]
Protective Documentation
You
cannot
work
everyone
up!
Defensible
practice :
Low
risk+CDR
Negative
D Dimer
PE Ruled
out
Protective Documentation
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Neat, thorough and legible
Risk factors
Chest pain… think ACS, PE, Dissection
Leg Exam ??? Homan’s
Clinical Gestalt
Clinical Decision rule (write PERC
negative)
• Let them know you are thinking!!!
Take Home Points
• PE - considered in patients who have
cardiopulmonary disease who present with
an apparent worsening of chest pain or
dyspneoa, or change in baseline
• Assign a risk
– Gestalt
– Clinical algorithm
• Pulmonary Embolism can cause ECG
changes that simulate ACS
Take Home Points
• Spiral Ct Scan- well established as
primary imaging modality
• Thrombolysis - Haemodynamically
unstable and cardiac arrest
• Document Clearly
Email:
slahri@webmail.co.
za
Thanks!