How is the severity of pulmonary embolism (PE) evaluated when determining treatment options and hospital admission?

Severity Assessment of Pulmonary Embolism for Treatment and Admission Decisions

The severity of pulmonary embolism should be evaluated using a structured risk stratification approach that includes hemodynamic stability assessment, validated clinical prediction rules, and evaluation of right ventricular dysfunction and cardiac biomarkers to determine appropriate treatment options and need for hospitalization. 1

Initial Risk Stratification

Hemodynamic Assessment

• First step: Identify patients with high-risk PE (massive PE) based on:
  • Presence of shock or hypotension (systolic BP <90 mmHg or drop ≥40 mmHg for >15 minutes) 1
  • Signs of hemodynamic compromise (tachycardia, poor peripheral perfusion)
  • These patients have >15% risk of early mortality and require immediate aggressive intervention 1

Clinical Prediction Rules

1. Pulmonary Embolism Severity Index (PESI):

   • Most extensively validated scoring system 1
   • Includes 11 variables with different weights:
     • Age (in years)
     • Male sex (+10 points)
     • Cancer (+30 points)
     • Chronic heart failure (+10 points)
     • Chronic pulmonary disease (+10 points)
     • Pulse rate ≥110 bpm (+20 points)
     • Systolic BP <100 mmHg (+30 points)
     • Respiratory rate >30 breaths/min (+20 points)
     • Temperature <36°C (+20 points)
     • Altered mental status (+60 points)
     • Arterial oxygen saturation <90% (+20 points)

2. Simplified PESI (sPESI):

   • More practical for clinical use 1
   • 1 point for each of:
     • Age >80 years
     • Cancer
     • Chronic pulmonary disease
     • Heart rate ≥110 bpm
     • Systolic BP <100 mmHg
     • Oxygen saturation <90%
   • sPESI = 0 identifies low-risk patients (30-day mortality risk ~1%)
   • sPESI ≥1 identifies intermediate/high-risk patients

Advanced Risk Stratification

Right Ventricular Dysfunction Assessment

• Imaging methods 1:
  • Echocardiography: RV dilatation, hypokinesis, increased RV/LV diameter ratio >0.9
  • CT pulmonary angiography: RV/LV diameter ratio >1.0
  • Look for specific signs like the "60/60 sign" (acceleration time <60ms with mid-systolic notch) 2

Laboratory Biomarkers

• Cardiac troponins: Indicate myocardial injury 1

  • High-sensitivity assays have excellent negative predictive value
  • Elevated levels associated with 5.9-fold increased risk in normotensive patients

• B-type natriuretic peptides (BNP, NT-proBNP): Indicate cardiac stretch 1

  • Elevated levels associated with 7.6-fold increased risk

• Other prognostic markers 1:

  • Lactate ≥2 mmol/L: Indicates tissue hypoperfusion
  • Hyponatremia: Associated with 5.6-fold increased mortality risk

Integrated Risk Classification

Based on the European Society of Cardiology guidelines 1, PE severity is classified as:

1. High-risk PE (massive):

   • Shock or hypotension present
   • Requires immediate aggressive intervention (thrombolysis, embolectomy)
   • Hospital admission to ICU mandatory

2. Intermediate-high risk PE (submassive):

   • Hemodynamically stable
   • PESI Class III-V or sPESI ≥1
   • Both RV dysfunction on imaging AND elevated cardiac biomarkers
   • Hospital admission required, consider ICU
   • May benefit from close monitoring and rescue reperfusion if deterioration occurs

3. Intermediate-low risk PE:

   • Hemodynamically stable
   • PESI Class III-V or sPESI ≥1
   • Either RV dysfunction OR elevated cardiac biomarkers (not both)
   • Hospital admission typically required

4. Low-risk PE:

   • Hemodynamically stable
   • PESI Class I-II or sPESI = 0
   • No RV dysfunction
   • Normal cardiac biomarkers
   • May be candidates for early discharge or home treatment

Treatment Decisions Based on Risk Stratification

• High-risk PE:

  • Immediate systemic thrombolysis if no contraindications
  • Consider catheter-directed interventions or surgical embolectomy if contraindications to thrombolysis exist
  • ICU admission 1

• Intermediate-high risk PE:

  • Anticoagulation with close monitoring
  • Consider rescue thrombolysis if clinical deterioration
  • Hospital admission, consider ICU 1

• Intermediate-low risk PE:

  • Anticoagulation
  • Hospital admission 1

• Low-risk PE:

  • Anticoagulation
  • Consider early discharge or home treatment if adequate support system exists 1

Special Considerations

• ECG findings: While not diagnostic alone, specific patterns like T-wave inversions in V1-V4, QR pattern in V1, and S1Q3T3 pattern can indicate RV strain and correlate with PE severity 2

• Concomitant DVT: The presence of DVT is an independent predictor of 30-day mortality (OR 1.9) 1

• Oxygen therapy: Provide supplemental oxygen for SaO2 <90%; consider high-flow nasal cannula or non-invasive ventilation before intubation in severe cases 1

Pitfalls to Avoid

1. Relying solely on clinical impression without using validated scoring systems
2. Overlooking RV dysfunction in patients with low PESI/sPESI scores (occurs in ~34% of "low-risk" patients) 1
3. Delaying treatment in high-risk patients while awaiting confirmatory testing
4. Failing to reassess patients with intermediate-risk PE who may deteriorate
5. Inappropriate use of thrombolysis in low-risk patients, increasing bleeding risk without mortality benefit 3

By systematically evaluating PE severity using this approach, clinicians can make appropriate decisions regarding treatment intensity and level of care required for optimal patient outcomes.