Rosen & Barkin's 5-Minute Emergency Medicine Consult (588 page)

• 428.1 Left heart failure
  
• 514 Pulmonary congestion and hypostasis
  
• 518.82 Other pulmonary insufficiency, not elsewhere classified
  

BASICS

• The majority of pulmonary embolisms (PEs) arise from thrombi in the deep veins of the lower extremities and pelvis.
  
• Thrombi also originate in renal and upper extremity veins.
  
• After traveling to lungs, the size of the thrombus determines signs and symptoms.
  

• Most patients with PE have identifiable risk factor:
  
  • Recent surgery
    
  • Pregnancy
    
  • Previous deep vein thrombosis (DVT)/PE
    
  • Stroke or recent paraplegia
    
  • Malignancy
    
  • Age >50 yr
    
  • Obesity
    
  • Smoking
    
  • Oral contraceptives
    
  • Major trauma
    
• Hematologic risk factors:
  
  • Factor 5 Leiden
    
  • Protein C or S deficiency
    
  • Antithrombin III deficiency
    
  • Antiphospholipid antibody syndrome
    
  • Lupus anticoagulant
    

• Thromboembolic disease is quite rare.
  
• Risk factors in children:
  
  • Presence of central venous catheter
    
  • Immobility
    
  • Heart disease
    
  • Trauma
    
  • Malignancy
    
  • Surgery
    
  • Infection
    

DIAGNOSIS

• Variability in signs and symptoms make diagnosis difficult
  
• Most common:
  
  • Dyspnea
    
  • Pleuritic chest pain
    
  • Tachypnea
    
• General:
  
  • Fevers (rarely >102°F)
    
  • Diaphoresis
    
• Pulmonary:
  
  • Cough
    
  • Hemoptysis (rarely massive)
    
  • Rales
    
• Cardiovascular:
  
  • Tachycardia
    
  • Syncope
    
  • Murmur
    
• Extremities:
  
  • Cyanosis
    
  • Evidence of thrombophlebitis
    
  • Lower-extremity edema
    
• Abdominal pain
  
• Symptoms similar in elderly but typically more subtle if age <40 yr
  

• Routine labs are nonspecific.
  
• CXR:
  
  • Used to rule out other causes
    
  • Most common findings with PE:
    
    • Normal
      
    • Nonspecific parenchymal abnormality
      
    • Atelectasis
      
  • Other findings with PE:
    
    • Pleural effusions
      
    • Pleural-based opacities (Hampton hump)
      
    • Elevated hemidiaphragm
      
    • Local oligemia (Westermark sign)
      
• ECG:
  
  • To rule out cardiac etiology
    
  • Usually normal in PE
    
  • Other findings include:
    
    • Nonspecific ST–T-wave changes (most common abnormality)
      
    • Sinus tachycardia
      
    • Left axis deviation
      
    • Right bundle branch block pattern
      
    • S1Q3T3 pattern is uncommon and not specific enough to rule in/out diagnosis.
      
• Modified Wells criteria:
  
  • Popular decision rule that can assist with risk stratification in combination with
    d
    -dimer
    
  • Each criterion is given numeric value and if total value <4, along with negative
    d
    -dimer, risk of PE is <2%:
    
    • Clinical signs/symptoms of DVT: 3 pts
      
    • PE is no. 1 diagnosis: 3 pts
      
    • Heart rate >100 bpm: 1.5 pts
      
    • Surgery or immobilization for 3 days within last 4 wk: 1.5 pts
      
    • Previous PE or DVT: 1.5 pts
      
    • Hemoptysis: 1 pt
      
    • Malignancy with treatment within last 6 mo: 1 pt
      
• Pulmonary Embolism Rule-out Criteria (PERC)
  
  • Useful in low prevalence setting (ED) in combination with low clinical suspicion.
    
    • Age <50 yr
      
    • Heart rate <100 bpm
      
    • O
      ₂
      saturation ≥95%
      
    • No hemoptysis
      
    • No estrogen use
      
    • No prior DVT or PE
      
    • No unilateral leg swelling
      
    • No surgery or trauma requiring hospitalization within the past 4 wk
      
  • <1% risk for PE/DVT in 45 days if PERC score 0
    

• Arterial blood gas:
  
  • Can show hypoxemia, hypocapnia, respiratory alkalosis, or increased alveolar–arterial (A–a) gradient
    
  • PE still possible with normal A–a gradient
    
  • Does not aid in diagnosis of PE
    
• CBC:
  
  • Anemia may be contributing factor to dyspnea.
    
• d
  -dimer enzyme-linked immunosorbent assay:
  
  • d
    -dimers are detectable at levels >500 ng/mL in nearly all patients with PE.
    
  • High sensitivity (close to 100%) with low specificity for PE
    
  • Almost always elevated in patients with malignancy or surgery within the last 3 mo
    
  • Multiple studies confirm that negative enzyme-linked immunosorbent assay
    d
    -dimer in combination with low clinical suspicion effectively rules out PE.
    

• Spiral chest CT with IV contrast:
  
  • Has ability to also detect alternative pulmonary abnormalities
    
  • Accurate for identifying PE in proximal pulmonary tree:
    
    • In patients with high pretest probability, positive predictive value of 96%
      
    • In patients with low pretest probability, negative predictive value of 96%
      
• Ventilation–perfusion scan (V/Q):
  
  • Results reported in probabilities and correlated to clinical suspicion
    
  • Probability of PE with V/Q results:
    
    • Normal or near normal V/Q scan: 4% probability for PE
      
    • Low-probability V/Q scan with low clinical suspicion: 4% probability for PE
      
    • Low-probability V/Q scan with high clinical suspicion: 16–40% probability for PE
      
    • Intermediate V/Q scan: 16–66% probability for PE
      
    • High-probability V/Q scan with low clinical suspicion: 56% probability for PE
      
    • High-probability V/Q scan with high clinical suspicion: 96% probability for PE
      
• Lower-extremity duplex US:
  
  • Used in patients who would otherwise require pulmonary angiogram
    
  • Presence of DVT requires same anticoagulation as PE.
    
  • Negative lower-extremity duplex does not rule out PE.
    
• Echocardiogram:
  
  • Used to assess for right heart strain or patent foramen ovale when thrombolysis is a possibility
    

Pulmonary angiogram:

• Gold standard for diagnosis
  
• Used when diagnosis not confirmed or excluded
  
• Higher complication rate than other modalities
  

• Anxiety disorder
  
• Aortic dissection
  
• Asthma
  
• Cardiac dysrhythmias
  
• Costochondritis
  
• Myocardial infarction
  
• Pericarditis
  
• Pneumonia
  
• Pneumothorax
  
• Rib fracture
  

TREATMENT

• Initial supplemental oxygen
  
• Establish IV access
  
• Cardiac monitor
  

• Airway, breathing, and circulation
  
• Provide supplemental oxygen to maintain adequate oxygen saturation.
  
• Intubate if unable to provide adequate oxygenation.
  
• Administer IV fluids carefully for hypotensive patients:
  
  • Excessive fluid expansion may worsen right heart failure.
    
• IV vasopressor therapy is indicated if hypotension does not resolve with IV fluids.
  

• Anticoagulation:
  
  • Prevents additional thrombus from forming
    
  • Stabilizes existent clot to prevent migration
    
  • Risk of minor/major bleeding with therapy
    
• Unfractionated heparin:
  
  • Dose titration fraught with difficulty leading to inadequate therapy
    
  • Goal to maintain partial thromboplastin time test between 1.5 and 2.5 times the control value (60–80 sec)
    
• Low-molecular-weight heparin:
  
  • At least as effective as unfractionated heparin in multiple prospective randomized trials
    
  • Therapeutic goal automatic with weight-based dosing
    
  • Easier administration and monitoring than heparin with some cost benefit
    
• Warfarin:
  
  • Oral therapy for long-term anticoagulation
    
  • Goal is international normalized ratio (INR) of 2–3
    
• Rivaroxaban:
  
  • Oral factor 10a inhibitor
    
  • Recently approved for treatment of PE
    
  • Does not require lab monitoring
    
  • Not recommended in renal/hepatic insufficiency or pregnancy
    
  • No specific antidote but has short half-life in case of bleeding
    
• Thrombolysis:
  
  • Initiate in hemodynamically unstable patients with confirmed PE.
    
  • Consider in stable patients with PE and severe hypoxemia, massive PE, or right ventricular dysfunction.
    
• Inferior vena cava filter:
  
  • Indicated in patients who have contraindications to anticoagulation or have been therapeutic on anticoagulation but failed prevention of PE
    
• Surgical or catheter embolectomy:
  
  • Consider in those with thrombolysis contraindications or failure, or deemed unstable for medical management.
    
  • Case-by-case basis