Pulmonary Embolism - NCI

Pulmonary Embolism
Pulmonary Embolus is a fragment of the
thrombus that breaks off and travels in
the blood until it lodges at the
pulmonary vasculature.

-The majority of clinically significant
pulmonary emboli begin in the pelvic or
lower extremity veins.
-The morbidity and mortality associated
with this disease remains unacceptably
high.
-It is estimated that 500,000 suffer from
pulmonary emboli each year and that
50,000 of those will die

Diagnosis of Pulmonary Embolism (PE)
1-Clinical picture.
2-Look for risk or predisposing factors for DVT
3-Look for ventilation-perfusion mismatch
4-Testing for PE.
-A chest radiograph
-ECG
-Ventilation-perfusion scanning (V/Q scanning).
-Angiography
-Spiral CT
-D-dimer

1-Signs and Symptoms of PE
• Dyspnea 73%
• Pleuritc Pain 66%
• Cough 43%
• Leg Swelling 33%
• Leg Pain 30%
• Hemoptysis 15%
• Palpitations 12%
• Wheezing 10%
• Angina-Like pain 5%
The signs and symptoms serve only to raise the suspicion of
pulmonary embolus

2-Predisposing Factors
Primary risk factors
Surgery
Major Trauma
Cancer
Congestive Heart Failure
Myocardial infarction
Immobilization
Minor risk factors
Obesity
Bed Rest
Estrogen therapy

3-Look for ventilation-perfusion mismatch
By calculating A-a O2 gradient = PaO2 (alveolar) - PaO2
(arterial)
Normal A-a O2 gradient is 5-20 and increases with age.
-Elevated in 80% to 90% in PE
-Normal in 10% to 20% in PE
PAO2 (alveolar) = 150 - 1.2(PaCO2), assuming patient
breathing room air
150 - 1.2 (40) = 102 150 – 1.2 (35) = 108
102-100 = 2 108 -100 = 8

4-Testing for PE
-A chest radiograph
-ECG
-Ventilation-perfusion scanning (V/Q scanning).
-Angiography
-Spiral CT
-D-dimer

Abnormalities on Chest Radiography
14% Normal
68% Atelectasis or parenchymal density
48% Pleural Effusion
35% Pleural based opacity
24% Elevated diaphragm
15% Prominent central pulmonary artery
7% Cardiomegally
5% Pulmonary edema

Figure 1
Atelectasis 68%
Figure1
Atelectasis and parenchymal densities are quite common. Most
of these densities are caused by pulmonary hemorrhage and
edema

Pleural Effusion 48%
Figure 2
Pleural effusions are common and most often unilateral
occupying less than 15% of a hemithorax

Figure 4
Elevated diaphragm 24%
A diaphragm may be elevated, reflecting
volume loss in the affected lung.

ECG of Acute pulmonary embolus
-An S1Q3T3 pattern:
prominent S wave in lead I, Q wave and
inverted T wave in lead III
-Sinus tachycardia
-T wave inversion in leads V1 - V3
-Right Bundle Branch Block
-low amplitude deflections

ECG of Acute pulmonary embolus

Ventilation-perfusion scanning
It visualizes the gas exchange in the lungs using
Xenon-133 and the perfusion of the lung using
technetium99m-labeled albumin aggregates.
In practical terms, the test can be:
* High probability.
• Intermediate probability.
• Low probability.
*Normal .

High probability V/P scan
3Figure
This V/P scan demonstrates a high probability
scan with multiple segmental defects and normal
ventilation in those areas

Intermediate probability V/P scan
scans with sub segmental defects or defects of any
size that match abnormalities on the chest x-ray
or the ventilation scan.

Interpretation of V/Q Scan
Interpretation
Clinical
Suspicion
Probability of
PE
Interpretation
High probability
High or
intermediate
96% +
Treat for PE
Medium probability
Medium probability
Intermediate
Low
33%
12%
Need further
evaluation
Need further
evaluation
Low probability
Low probability
High
Low
16%
4% <
Need further
evaluation
No PE
Normal
Low
2%
No PE

Pulmonary angiogram
It is the "gold standard" test
If you absolutely must know whether the patient had pulmonary
embolism there is no substitute for a well done angiogram.
With the angiogram you look for cut-offs in
the vascular tree or for intraluminal filling
defects.

Pulmonary angiogram showing
intraluminal filling defects.

Computed
Tomography
The typical appearance of a pulmonary
infarct on CT includes a pleural based
density with convex borders and a
linear strand at the apex of the triangle.
The differential diagnosis for this
abnormality includes infarct,
hemorrhage, pneumonia, fibrosis,
neoplasia and edema.

D-dimer
-A marker for thrombosis and fibrinolysis, can
be useful in the exclusion of PE.
- Specific conditions that will give positive D-
dimer tests include trauma, postoperative state,
and malignancies.
-30% with PE will have normal D-dimer

Treatment of Pulmonary Embolism
1- Treat as for any respiratory distress including O2,
monitoring, fluid resuscitation for secondary
right-sided heart failure, Inotropic.
2-Anticoagulant : Heparin, oral anticoagulant
and LMWH.
3- Thrombolysis.
4- Caval Interruption.

2-Anticoagulant
Heparin
- A loading dose of 5,000 U followed by approximately 1,000
U/h.
OR: a bolus dose of 10,000-15,000 u for PE.
weight-based dosing.
A bolus with 80 U/kg and start a drip at 18 U/kg/h.
-Check PTT in 6 hours. Keep the PTT at 1.5 to 2 times
control. Adjust dose as per protocol in. Use clinical judgment!

Adjustment of weight-based dosing
APTT (sec)
Dose Change
Additional Action
Next PTT
(U/kg/hr
)
( hr)

-Heparin, 25,000 IU in 250 ml D5W. Infuse at rate
dictated by body weight through an infusion
apparatus calibrated for low flow rates.
-During the first 24 hr, repeat APTT every 6 hr.
Thereafter, monitor APTT once every morning
unless it is outside the therapeutic range.
- Hypercoagulable state will exist when heparin is
stopped (if the duration of heparin has been at least
72 hours.)

Warfarin
It depletes vitamin K-dependent clotting factors (II, VII, IX, and X).
-It is taken orally. Begin with 5 mg QHS.
-Warfarin therapy can begin on day one of heparin therapy.
- A ratio of treated to control PT (INR-International
normalization ratio) of 2 to 3 is considered therapeutic.
- Monitor daily using the PT (Prothrombin time), until
a stable INR for 2 days. Then 2 to 3 times weekly for 1 to 2
weeks, and then monthly.
-Heparin should be continued for at least 4 days total and for at
least 2 days after a therapeutic INR is obtained.
-Continue using anticoagulation (warfarin) for at least
6 months.

3-Thrombolysis:
(Patients still require heparin)
If PE is confirmed with angiogram or high-probability V/Q and
there is:
- Evidence of right heart failure, unresponsive to standard
therapy.
- Respiratory failure from PE, but the benefits are less well
established.
* Regimens approved by FDA:
- Streptokinase 250,000 IU over 30 minutes followed by 100,000
IU/hr for 24 to 72 hours.
-TPA 100 mg as continuous infusion over 2 hours.-
* Catheter-directed thrombolysis. is rarely used.

4-
Caval Interruption:
-If anticoagulation is contraindicated or
ineffective, consider vena cava
interruption with a filter such as the
Greenfield filter.
-Vena cava filters are less effective than
anticoagulation and may lead to
increased rates of DVT and may not
protect against PE (same PE and death
rates as controls).

Postoperative DVT Prophylaxis
- If not given prophylaxis, 15% to 30% of
those with abdominal surgery will
develop a DVT.
-DVT prophylaxis after surgery is cost
effective and reduces the incidence of
DVT and PE.

-Heparin (unfractionated): 5000 units SQ Q12h.
-Graded compression stockings: Effective and
have few side effects.
-low-molecular-weight heparin .
-Warfarin: Less effective than LMWH
-Aspirin: Not very effective.

Only low-molecular-weight heparin and
graded compression stockings have
been shown to reduce the incidence of
pulmonary embolism.

low-molecular-weight heparin LMWH
(anti-factor Xa )
- Enoxaparin: (Clexane)
- Dalteparin.
-Nadroparin calcium. (Fraxiparine)
-Tinzaparin sodium . (Innohep)

-
Enoxaparin:
(Clexane)
(100IU=mg=0.01ml) (2000IU=20 mg =0.2ml & 4000IU= 40
mg= 0.4ml)
No need to follow PT/INR/PTT.
The best studied LMW heparin.
DVT prophylaxis after abdominal surgery 40mg SQ once -
daily starts 2 hours before surgery.
-In high risk 12 h before surgery. -
-In spinal or epidural anesthesia, it should be 10-12 h before
and subsequent dose 2h after removal of catheter.
Continue until patient is ambulatory (7-10) or up to 14 days.
The dose must be adjusted for renal function. Use with caution
in renal and hepatic disease.

low-molecular-weight heparin in PE
-Enoxaparin sodium100IU/kg twice
daily injection
-Oral anticoagulant should be initiated and
Enoxaparin sodium should be continued
until therapeutic effect (INR 2-3)

Preoperative Management of Patient with
Anticoagulant:
-When to Stop Oral Anticoagulation? 3-5 days
-Heparin Coverage Needed Preoperatively? Yes, if
history of thromboembolism 1 month
-Restart Anticoagulation Postoperatively with IV
heparin or SQ LMWH (Note: Simultaneously Resume
Prior Oral Anticoagulation)
-Restart heparin 12 hours after surgery, unless there is
bleeding, in this case it should be delayed.

Thank You •