Pulmonary embolism

Question 1

Pulmonary embolism ethiopathogenesis

Answer 1

Thrombi originating mostly in the deep veins of the lower limbs & pelvis gets detached-> pass through IVC-> right atrium & ventricle-> lodge in pulmonary arteries-> hemodynamic compromise (due to “pulmonary infarct” in the lung)

It remains undiagnosed in 80% of cases

Causes: gross ventilation-perfusion inequality

Eventually results in “pulmonary infarct”

Question 2

Pulmonary embolism clinical features

Answer 2

Symptoms
1. dyspnea, chest pain, hemoptysis (triad)
2. symptoms: gradually progressive dyspnea (minor)-> sudden catastrophic hemodynamic collapse (major)-> chest pain-> hemoptysis
3. Atypical symptoms: seizures, syncope, delirium, wheezing

Signs
1. most consistent finding: tachycardia, tachypnoea
2. massive embolus: shock & cyanosis (dangerous)
3. Others: rales (58%), accentuated 2nd heart sound (53%), diaphoresis (36%)

Question 3

Pulmonary embolism investigations

Answer 3

1. chest x-ray: diminished pulmonary vascular markings in 50% cases when done within 24-48 hours of attack

Massive embolism: sudden cardiac arrest-> death
Moderate embolism: pyramidal-wedge-shaped infarcts in lungs-> “Westermark sign & Hamptom’s lump”

2. ECG: ST segment depression & T-wave inversion
3. CT Angiogram & MR Angiogram (GOLD STANDARD): saddle-type of pulmonary embolus can be seen from main pulmonary artery
4. Radioisotope ventilation-perfusion (VQ) scan of lung: evidence of VQ mismatch-> highly suggestive of pulmonary embolism
   - high probability scan for right-sided pulmonary embolism (when no radio-isotope is taken in perfusion but both ok in ventilation-> mismatch)

Question 4

Limitations of MRI

Answer 4

1. Acutely ill patient
2. long test times
3. patient monitoring
4. sedation requirement for kids
5. lower sensitivty and specificity compared to CT

Question 5

Differential diagnosis of pulmonary embolism

Answer 5

1. Acute MI
2. Pneumonia
3. Musculoskeletal disorders

Question 6

Scoring system

Answer 6

Well’s Scoring System (like in DVT but different criterias)
1. Clinical signs & symptoms of DVT (minimum of leg swelling & pain with palpation of the deep veins)- 3 points

2. PE is the primary diagnosis/likely- 3 points
3. HR>100BPM- 1.5 points
4. Surgery in previous 4 weeks/immobilization >3days- 1.5 points
5. Previous DVT/PE- 1.5 points
6. Haemoptysis- 1 point
7. Malignancy (with tx in past 6 months/palliative)- 1 point

> 4: PE likely
4/<: PE unlikely

Question 7

Treatment of PE

Answer 7

1. O2: >94% maintain (SPO2) [ventilation support]
2. pain relief (injection morphine)
3. Main:
   - Anticoagulation with LMWH 1mg/kg SQ every 12H
   - UFH 5000 units IV bolus, followed by 1000-1300 units/hr infusion
4. thrombolysis (catheter-directed) with tissue plasminogen activator-tPA-Alteplase-10mg IV over 2 minutes-> 90mg over 2 hours OR weight>65 kg-> 1.5mg/kg infusion

If patient still not responding to therapy…..proceed with

5. pulmonary surgical embolectomy
   - done in case failure of thrombolytic tx for a massive pulmonary embolus

Question 8

Treatment algorithm for PE (PE advanced care protocol)

Answer 8

CATEGORY
1. non-massive + low risk submassive-> heparin alone

2. high risk submassive
   - low bleeding risk-> 1/2 dose tPA/Alteplase OR catheter-directed thrombolysis
   - high bleeding risk-> catheter-directed thrombolysis
3. massive
   - low bleeding risk-> full dose tPA, catheter-directed thrombolysis, pulmonary embolectomy (if no improvement)
   - high bleeding risk-> catheter-directed thrombolysis, pulmonary embolectomy

Question 9

High risk PE

Answer 9

1. Looks clinically unstable
2. poor clinical course
3. Worrisome echo
4. Syncope, severe hypoxia
5. Elevated lactate, BNP, Trop
6. Large residual thrombus