Acute pulmonary embolism - Internal medicine

Question 1

Definition of Acute pulmonary embolism

Answer 1

• Pulmonary thromboembolism means occlusion of the pulmonary vasculature by a blood clot.
• 95% of emboli originates from deep venous thrombosis (DVT) in the pelvis or deep leg veins.

Question 2

Etiology of pulmonary embolism

Answer 2

• Thromboembolism sources
  o DVT (common) or right ventricular thrombus (rare)
• Fat embolism … post bone surgery
• Amniotic fluid embolism … post delivery
• Neoplastic embolism
• Parasitic embolism

Question 3

Risk factors of thromboembolism (A++)

Answer 3

Virchow’s triad
1- Stasis
o Recent surgery, especially abdominal/pelvic and lower limb or hip/knee replacement.
o Leg fracture.
o Prolonged bed rest/reduced mobility.
o Hospitalization for acute critical illness as myocardial infarction or heart failure.
o Prolonged airway travel

2- Hypercoagulable state
o Pregnancy/postpartum
o Combined oral contraceptive pills (OCPs) use
o Coagulation disorders (e.g., protein C/protein S deficiency, factor V Leiden)
o Malignancy
o Severe burns
o Myeloproliferative disorder
o Antiphospholipid syndrome.
o Hormonal replacement therapy (HRT).

3- Endothelial dysfunction
o Diabetes mellitus
o Dyslipidemia
o Hypertension
o Obesity

Question 4

Pathogenesis of pulmonary embolism

Answer 4

• Pulmonary embolism (PE) usually arises from deep venous thromboses (DVTs) in the pelvis or leg veins.
• Clots break off and pass through the veins and the right side of the heart before lodging in the pulmonary circulation and block blood flow to lungs resulting in impaired gas exchange and circulation.
• Lower lobes of the lung are more frequently affected than upper lobes
• Larger embolism occludes the main pulmonary artery, while smaller ones occlude peripheral arteries.
• PE often leads to pulmonary infarction, right sided heart failure, and hypoxemia.

Question 5

Clinical presentation of pulmonary embolism (B)

Answer 5

Depends on
- Size of the occluded pulmonary artery
- Time of development: acute or chronic showers
- Lung reserve: more severe symptoms in patients with preexisting pulmonary conditions
* Dyspnea (acute severe dyspnea or rapidly progressive dyspnea within days)
* Chest pain.
* Syncope or pre syncope
* Hemoptysis
* Cardiogenic shock

Question 6

Management of patient with suspected acute pulmonary embolism (ABCDE approach) (A++)

Answer 6

A) Airway: check for any signs of air way obstruction
B) Breath: the patient would suffer dyspnea, tachypnea, and/or desaturation but with clear back
C) Circulation: Frequently tachycardia with or without hypotension or obstructive shock and don’t forget to check ABG for metabolic disturbances
D) Disability: disturbed conscious level could be present in setting of obstructive shock and don’t forget to check random blood sugar not to miss associated diabetic ketoacidosis
E) Exposure and brief examination could reveal congested neck veins and accentuated heart sounds

Question 7

Management of patient with suspected acute pulmonary embolism (DD of acute dyspnea with clear back) (A++)

Answer 7

• Acute pulmonary embolism
• Cardiac tamponade
• Acute coronary syndrome
• Metabolic dyspnea (diabetic keto acidosis or acute renal failure)
• Psychogenic dyspnea

Question 8

Management of patient with suspected acute pulmonary embolism (Emergency diagnostic work up) (A++)

Answer 8

1- Suspected pulmonary embolism with hemodynamic compromise (hypotension or shock)
o The investigation of choice is CT pulmonary angiography that will visualize the pulmonary embolus as filling defect
o If not available … Transthoracic or transesophageal echocardiography could detect dilated right side of the heart and pulmonary hypertension secondary to acute pulmonary embolism

2- Suspected pulmonary embolism without hemodynamic compromise
o First you have to assess the clinical probability of acute pulmonary embolism using mobile app Well’s score (check in app store)
▪ Pulmonary embolism is likely when score is above 4 … Order CT pulmonary angiography to rule in or rule out acute pulmonary embolism
▪ Pulmonary embolism is unlikely when score is equal or below 4 …Order D-dimer
* If negative D-dimer …. Acute pulmonary embolism could be ruled out
* If positive D-dimer …. Order CT pulmonary angiography to rule in or rule out acute pulmonary embolism
* D-dimer is a good negative test that could be elevated in many clinical disorders as inflammation, infection, pregnancy, or cancer

Question 8

Management of patient with suspected acute pulmonary embolism (Emergency treatment) (A++)

Answer 8

1- Confirmed acute pulmonary embolism with hemodynamic compromise (high risk)
o Oxygen therapy: to support hypoxia
o Cautious IV fluids to support blood pressure
o IV vasopressors and/or inotropes to support Blood pressure
o Thrombolytic therapy
▪ The window for thrombolytic therapy in acute pulmonary embolism reaches 14 days
▪ The dose of streptokinase in acute pulmonary embolism
* Rapid protocol …. 1.5 million IU over 2 hours
* Slow protocol …. 250,000 IU over 30 minutes then 100,000 IU/hour over 12-24 hours
▪ Other thrombolytics are better than streptokinase as recombinant tissue plasminogen activator (rTPA) with a dose of 100 mg over 2 hours
a- IF thrombolytic therapy is failed or contraindicated … urgent interventional pulmonary embolectomy or urgent surgical pulmonary embolectomy should be considered
b- After reperfusion therapy the patient must receive anticoagulation as will be described below for low-risk patients

2- Confirmed acute pulmonary embolism without hemodynamic compromise(low risk)
o Parenteral anticoagulation and warfarin simultaneously.
- Unfractionated heparin
- Low molecular heparin: enoxaparin or fondaparinux.
o Parenteral anticoagulation as bridging therapy till onset of warfarin action to be stopped when INR is between 2-3 and continue warfarin for 3 months
o Direct oral anticoagulation (rivaroxaban or apixaban) without parenteral anticoagulation and without INR monitoring but with special doses
▪ Rivaroxaban 15 BID for 21 days then, 20 mg OD for 3 months
▪ Apixaban 10 mg BID for 7 days then, 5 mg BID for 3 months.

Question 9

Management of patient with suspected acute pulmonary embolism (Other investigations) (C)

Answer 9

1- Cardiac enzymes (Troponin& CKMB): elevated in high-risk patients
2- ECG: Sinus tachycardia with right ventricular hypertrophy or right bundle branch block. Sinus tachycardia+S1Q3T3 are characteristic but nonspecific ECG finding in cases of PE.
3- Ventilation /perfusion (V/Q lung scintigraphy):
a. is useful in patients with history of contrast anaphylaxis and pregnant patients
b. V/Q scan assesses both ventilation and perfusion
c. Good ventilation with poor perfusion is diagnostic for acute pulmonary embolism
4- Doppler venous system of both lower limbs: to evaluate presence of DVT as a common source of acute pulmonary embolism
5- investigations to search for specific hypercoagulable cause
a. Screening for Anti phospholipid antibody syndrome (lupus-anticoagulant, anticardiolipin, Anti B2 glycoprotein) …. If diagnosed only warfarin is indicated for life as direct oral anticoagulation is contraindicated (MCQ)
b. Screening for (factor V lieden, Anti thrombin III)
c. Screening for protein C and protein S
d. Pelviabdominal u/s to search for occult malignancy

Question 10

Indications used in Acute pulmonary embolism (A++)

Answer 10

Indications of extended oral anticoagulation after 3 months
1- Recurrent acute pulmonary embolism
2- Acute pulmonary embolism with unknow cause or risk factor
3- Acute pulmonary embolism secondary to untreatable condition as hypercoagulable state
4- Acute pulmonary embolism secondary to active cancer

Indications of inferior vena cava filter
1- Recurrent DVT and pulmonary embolism despite adequate anticoagulation
2- Patients with contraindications to anticoagulation

Indications for Prophylaxis against pulmonary embolism (rivaroxaban 10 mg OD or apixaban 2.5 mg BID)
1- Bed ridden patients
2- After surgery needing prolonged recumbence (orthopedic surgery)
3- Fractured patients
4- Cancer patient