Updated: 5/29/2020

Pulmonary Embolism

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Snapshot
  • A 36-year-old woman presents to the emergency department with worsening shortness of breath and pleuritic chest pain. Her symptoms began earlier in the day while she was waiting for her bus to return home. She recently returned from China to the United States for a business meeting. She denies any sick contacts and has not had these symptoms in the past. Medical history is unremarkable. She takes an oral contraceptive and a daily multivitamin. Her temperature is 98.6°F (37°C), blood pressure is 135/82 mmHg, pulse is 112/min, respirations are 24/min, and oxygen saturation is 89% on room air. A CT angiogram performedmed and demonstrates a filling defect in the pulmonary vasculature. She is immediately started on supplemental oxygen and heparin.
Introduction
  • Definition
    • mechanical obstruction of the pulmonary vascular secondary to a blood clot
      • typically the blood clot is a thromboembolism from a deep vein thrombosis (DVT)
  • Epidemiology
    • risk factors
      • prolonged immobilization (e.g., long travel)
      • malignancy
      • thrombophilia
      • pregnancy
      • hormonal contraceptives
  • Etiology
    • DVT (most common) 
      • from the veins of the proximal thigh (iliac, femoral, or popliteal)
    • phlegmasia cerulea dolens 
      • a progression from a DVT
      • massive thrombus that can embolize from the proximal ileofemoral vein
      • enlarged, blue, and tender lower extremity
    • septic embolism from right-heart endocarditis
    • fat embolism
    • amniotic fluid embolism
  • Pathophysiology
    • occlusion of the pulmonary vasculature results in hypoxemia and subsequent pulmonary vasoconstriction
      • the increased pulmonary constriction causes an increase in pulmonary vascular resistance, which decreases right ventricular stroke volume leading to
        • increased ventricular oxygen demand
        • right ventricular dilatation
        • decreased left ventricular preload (leading to circulatory failure)
        • poor blood flow to the lung, leading to a ventilation-perfusion mismatch
  • Prognosis
    • significantly high mortality without treatment
    • Wells' criteria
      • used to assess for risk of pulmonary embolism (sum the points)
        • signs and symptoms of DVT +3
        • pulmonary embolism (PE) is the most likely diagnosis +3
        • pulse is 100/min +1.5
        • surgery within the past 4 weeks or immobilization for the past 3 days + 1.5
        • previously diagnosed PE or DVT + 1.5
        • hemoptysis +1
        • malignancy with treatment in the past 6 months
      • < 2 points
        • low risk
        • 1.3% incidence of PE
        • consider using d-dimer
      • 2-6 points
        • moderate risk
        • 16.2% incidence of PE
        • consider high sensitivity d-dimer or CTA
      • > 6 points
        • high risk
        • 37.5% incidence of PE
        • consider CTA
Presentation
  • Symptoms
    • dysnea (most common)
    • pleuritic chest pain
    • cough
    • hemoptysis
    • syncope in cases of a large PE
  • Physical exam
    • tachypnea
    • tachycardia
    • loud P2
    • hemodynamic instability in cases of a large PE
Imaging
  • CT angiography of the chest
    • indication
      • imaging study of choice in the diagnostic evaluation of PE
        • sensitivity of ~90%
        • specificity of ~95%
    • comments
      • chest radiography is typically normal or it may show 
        • pleural effusions 
        • Hampton hump (wedged-shaped infarct)
        • Westermark sign (avascularity distal to the PE)
  • V/Q scan
    • indication
      • performed if the pre-test probability of PE is high but the patient cannot undergo a CT angiogram (e.g., renal failure, pregnancy, or unavailability) 
    • interpretation
      • normal
        • rules out PE
      • high-probability
        • treat with heparin
      • low or intermediate probability
        • if clinical suspicion is high, then get a pulmonary angiography
  • Venous duplex ultrasound of the lower extremities
    • indication
      • to evaluate if there are DVTs
Studies
  • ECG
    • findings
      • sinus tachycardia
      • atrial fibrillation
      • right ventricular strain
      • S1Q3T3
        • presence of S wave in lead I and Q wave and inverted T wave in lead III
      • T-wave inversions in V1-V4
  • Arterial blood gas
    • findings
      • hypoxemia
      • hypocapnia
      • respiratory alkalosis
      • alveolar-arterial gradient may be elevated
  • D-dimer
    • has a high sensitivity but poor specificity for PE and a high negative predictive value 
      • used to rule-out PE if there is a low pre-test probability 
        • a positive D-dimer in a low risk patient must be followed by a confirmatory study (CTA chest) 
Differential
  • Myocardial infarction
    • differentiating factor
      • coronary angiography demonstrating coronary occlusion
  • Costochondritis 
    • differentiating factor
      • pain with palpation or movement of the arm
Treatment
  • Medical
    • Non-vitamin K anticoagulation
      • indication
        • initial therapy in patients with PE in order to prevent further clot formation
          • treatment should not be delayed
      • medication options (best initial step in high risk patient with obvious PE)  
        • low-molecular weight heparin 
          • do not give in renal failure
        • unfractionated heparin 
          • dose by monitoring aPTT
          • preferred in kidney injury/failure
    • warfarin
      • indication
        • typically given around the same time as a non-vitamin K anticoagulant is given
          • dose based on INR (goal is 2-3)
    • thrombolytic therapy 
      • indication
        • performed in patients with PE who are hemodynamically unstable
  • Operative
    • embolectomy 
      • indication
        • performed in patients with PE who are hemodynamically unstable and thrombolytic therapy is contraindicated or who fail thrombolysis
    • IVC filter
      • indication
        • performed in patients with PE who have a contraindication or failure of anticoagulation 
Complications
  • Cor pulmonale
  • Recurrent pulmonary embolism
  • Atrial fibrillation or flutter
 

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(M2.PL.17.4687) A 25-year-old woman with bipolar disorder and schizophrenia presents to the emergency room stating that she is pregnant. She says that she has been pregnant since she was 20 years old and is expecting a baby now that she is breathing much harder and feeling more faint with chest pain caused by deep breaths. Her hospital medical record shows multiple negative pregnancy tests over the past 5 years. The patient has a 20 pack-year smoking history. Her temperature is 98°F (37°C), blood pressure is 100/60 mmHg, pulse is 110/min, respirations are 28/min, and oxygen saturation is 90% on room air. Her fingerstick glucose is 100 mg/dL. She has a large abdominal pannus which is soft and nontender. Her legs are symmetric and non-tender. Oxygen is provided via nasal cannula. Her urine pregnancy test comes back positive and an initial chest radiograph is unremarkable. What is the next best step in diagnosis?

QID: 107464
1

CT angiogram

6%

(15/248)

2

D-dimer

33%

(82/248)

3

Psychiatry consult for pseudocyesis

27%

(67/248)

4

Ultrasound

19%

(47/248)

5

Ventilation-perfusion scan

12%

(31/248)

M 6 D

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(M3.PL.16.51) A 43-year-old woman presents to her primary care physician with complaints of mild shortness of breath and right-sided chest pain for three days. She reports that lately she has had a nagging nonproductive cough and low-grade fevers. On examination, her vital signs are: temperature 99.1 deg F (37.3 deg C), blood pressure is 115/70 mmHg, pulse is 91/min, respirations are 17/min, and oxygen saturation 97% on room air. She is well-appearing, with normal work of breathing, and no leg swelling. She is otherwise healthy, with no prior medical or surgical history, currently taking no medications. The attending has a low suspicion for the most concerning diagnosis and would like to exclude it with a very sensitive though non-specific test. Which of the following should this physician order?

QID: 103342
1

Obtain spiral CT chest with IV contrast

0%

(0/1)

2

Obtain ventilation-perfusion scan

0%

(0/1)

3

Obtain chest radiograph

0%

(0/1)

4

Order a lower extremity ultrasound

0%

(0/1)

5

Order a D-dimer

100%

(1/1)

M 10 E

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(M3.PL.15.70) A 64-year-old female with a known diagnosis of metastatic breast cancer presents to the emergency department after decompensating while at the chemotherapy suite. On arrival vitals are: pulse 124 bpm, blood pressure 92/64 mmHg, temperature 98.5 F, respiration 24/min and shallow. The patient is diaphoretic and disoriented, but able to complain about excruciating chest pain. Labs are drawn, and the patient is quickly worked up with an EKG (Figure A) and helical CT (Figure B). The patient is started on a heparin drip. Which of the following results confers a poor prognosis for the patient?

QID: 102699
FIGURES:
1

Elevated white blood cell count

0%

(0/0)

2

Decreased d-dimer

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(0/0)

3

Elevated d-dimer

0%

(0/0)

4

Elevated troponin

0%

(0/0)

5

Decreased ionized calcium

0%

(0/0)

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(M2.PL.14.62) A 50-year-old man presents to the emergency department with chest pain. He states that it began earlier today and worsens with inspiration. It is non-exertional, 7/10 in severity, and sharp in nature. He states that he just returned from China yesterday and has not had any similar symptoms prior to today. He noticed that he has coughed up a small amount of blood-tinged sputum several times as well. He is otherwise healthy, other than having his foot splinted 4 days ago for an Achilles tendon injury he sustained while playing volleyball. His temperature is 97.9°F (36.6°C), blood pressure is 112/68 mm Hg, pulse is 120/min, respirations are 23/min, and oxygen saturation is 92% on room air. Physical exam is notable for an uncomfortable man who is mentating appropriately and moving all his extremities. Inspection of his lower extremities reveals a swollen and tender calf on the leg that is splinted. An ECG is seen in Figure A. The patient is started on IV fluids and oxygen. Which of the following is the next best step in management?

QID: 103425
FIGURES:
1

CT angiogram

35%

(6/17)

2

D-dimer

6%

(1/17)

3

Heparin

29%

(5/17)

4

Tissue plasminogen activator

29%

(5/17)

5

Ultrasound

0%

(0/17)

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Evidence (13)
EXPERT COMMENTS (25)
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