What are the primary breathing signs of pulmonary embolism and how is it treated?

Primary Breathing Signs of Pulmonary Embolism and Treatment

The most common breathing signs of pulmonary embolism (PE) are breathlessness and tachypnea (respiratory rate >20/min), which are present in most patients with PE; in the absence of these symptoms, pleuritic chest pain or hemoptysis is usually due to another cause. 1

Clinical Presentation of Pulmonary Embolism

Respiratory Signs and Symptoms

• Dyspnea: Most frequent symptom (present in ~80% of cases)
  • Often acute and severe in central PE
  • May be mild and transient in peripheral PE
  • May manifest as worsening of pre-existing dyspnea in patients with cardiopulmonary disease 1, 2
• Tachypnea (>20 breaths/min): Common finding 1
• Hypoxemia: Frequent, though up to 40% of patients may have normal arterial oxygen saturation 1
• Hypocapnia: Often present 1
• Hemoptysis: Less common (5-7% of cases) 2

Associated Signs and Symptoms

• Chest pain: Second most common symptom (39-56% of cases)
  • Usually pleuritic in nature due to distal emboli causing pulmonary infarction
  • May have angina-like character in central PE 1, 2
• Syncope or presyncope: Present in 22-26% of cases
  • Associated with higher prevalence of hemodynamic instability and right ventricular dysfunction 1, 2
• Signs of massive PE:
  • Collapse/hypotension
  • Unexplained hypoxia
  • Engorged neck veins
  • Right ventricular gallop 1, 3

Diagnosis

Clinical Probability Assessment

Assess clinical probability using these questions:

1. Is another diagnosis unlikely? (chest radiograph and ECG are helpful)
2. Is there a major risk factor? (recent immobility/surgery, pregnancy/postpartum, major medical illness, previous VTE)

Classification:

• Low = neither factor present
• Intermediate = either factor present
• High = both factors present 1

Diagnostic Workup

1. D-dimer testing: Useful when used appropriately

   • Not a routine screening test
   • Only consider with reasonable suspicion of PE
   • Only negative results are valuable
   • Should not be performed if:
     • Alternative diagnosis is highly likely
     • Clinical probability is high
     • Probable massive PE 1

2. Imaging:

   • CTPA (CT pulmonary angiography): First-line imaging test
   • Echocardiography: Not recommended for routine diagnosis in stable patients but essential in suspected high-risk PE 1
   • Leg ultrasound: Alternative to lung imaging in those with clinical DVT 1

Treatment

Initial Management Based on Risk Stratification

1. High-risk PE (with shock or hypotension):

   • Immediate oxygen therapy for hypoxemic patients
   • Intravenous unfractionated heparin: 80 units/kg bolus 1, 3
   • Consider systemic thrombolysis: Alteplase 100 mg over 2 hours if no contraindications 3
   • In cardiac arrest: CPR + 50 mg alteplase IV 1

2. Non-high-risk PE (hemodynamically stable):

   • Anticoagulation with direct oral anticoagulants (DOACs) preferred:
     • Apixaban, Rivaroxaban, Edoxaban, or Dabigatran
   • Low molecular weight heparin (LMWH) or fondaparinux preferred over unfractionated heparin
   • Unfractionated heparin recommended in patients with high bleeding risk or severe renal dysfunction 3

Advanced Interventions for High-Risk PE

• Surgical embolectomy: When thrombolysis is contraindicated or has failed 3
• Catheter-directed interventions: Alternative when surgical options are unavailable 3
• ECMO: Consider in cases of refractory circulatory collapse or cardiac arrest 3

Hemodynamic and Respiratory Support

• Fluid management: Modest fluid challenge (500 mL) if hypotensive, avoiding aggressive volume expansion 3
• Vasopressors: Norepinephrine for persistent hypotension 3
• Inotropes: Consider dobutamine/dopamine for low cardiac output with normal blood pressure 3
• Ventilation strategy: If mechanical ventilation needed, use low tidal volumes (~6 mL/kg), cautious PEEP, and keep plateau pressure <30 cm H₂O 3

Duration of Anticoagulation

• At least 3 months for all patients
• Consider indefinite anticoagulation for:
  • Recurrent PE not related to transient risk factors
  • Unprovoked PE
  • Persistent risk factors
  • Antiphospholipid syndrome 3

Important Clinical Pitfalls

1. Missing PE diagnosis: Remember that PE can present with non-specific symptoms; maintain high index of suspicion when dyspnea, tachypnea, chest pain, or syncope are present without clear alternative explanation 2

2. Inappropriate D-dimer testing: D-dimer should not be used as a screening test but only in patients with reasonable suspicion of PE 1

3. Delayed treatment: Initiate anticoagulation promptly in patients with high clinical suspicion while awaiting confirmatory tests 3

4. Inadequate risk stratification: Failure to identify high-risk PE can lead to delayed implementation of appropriate reperfusion strategies 1

5. Post-PE syndrome: Be aware that survivors may develop chronic complications including persistent right ventricular dysfunction and decreased quality of life 4