USMLE Prep - Medical Reference Library

Pulmonary Embolism — Risk Stratification & Outpatient Management

System: Pulmonology • Reviewed: Aug 31, 2025 • Step 1Step 2Step 3

Synopsis:

Use PESI/sPESI and Hestia criteria to identify low‑risk PE for outpatient therapy; ensure reliable anticoagulation access and follow‑up.

Key Points

  • Stabilize ABCs; begin targeted evaluation without delaying life-saving therapy.
  • Use system-specific risk tools to guide testing and disposition.
  • Order high-yield tests first; escalate imaging when indicated.
  • Start evidence-based initial therapy and reassess frequently.

Algorithm

  1. Primary survey and vitals; IV access and monitors.
  2. Focused history/physical; identify red flags and likely etiologies.
  3. Order system-appropriate labs and imaging (see Investigations).
  4. Initiate guideline-based empiric therapy (see Pharmacology).
  5. Reassess response; arrange consultation and definitive management.

Clinical Synopsis & Reasoning

PE spans from incidental subsegmental disease to obstructive shock. Evaluate pretest probability (e.g., Wells/Geneva), apply age‑adjusted D‑dimer when appropriate, and use CTPA or V/Q based on renal function, pregnancy, and contrast tolerance. Risk‑stratify by RV dysfunction (echo/CT), biomarkers (troponin/BNP), and clinical instability to anticipate decompensation.


Treatment Strategy & Disposition

Anticoagulate promptly when suspicion is high and bleeding risk acceptable; choose DOACs for most stable patients, LMWH in cancer, and UFH if thrombolysis or procedures are possible. Consider systemic thrombolysis or catheter‑directed therapy for massive/submassive PE with deterioration. Assess for precipitating factors and plan duration of therapy (provoked 3 mo; unprovoked often extended). ICU for shock or advanced support; otherwise ward or outpatient pathways for low‑risk cases with reliable follow‑up.


Management Notes

Document shared decision-making. Provide a written anticoagulation plan.


Epidemiology / Risk Factors

  • Smoking/chronic lung disease; infections or immobility (VTE)

Investigations

TestRole / RationaleTypical FindingsNotes
CXRInfection/edema/PTXConsolidation/effusion/PTX
ABG/VBGOxygenation/ventilationHypoxemia/hypercapnia
CT chest (indicated)PE/otherFindings vary

Outpatient Candidacy (Examples)

ToolLow‑Risk Definition
sPESIScore 0
HestiaAll criteria negative
No RV strainNormal echo/biomarkers
Reliable supportAdherence and follow‑up assured
No contraindicationsBleeding risk acceptable

Pharmacology

MedicationMechanismOnsetRole in TherapyLimitations
Catheter-directed therapyLocalized fibrinolysis/thrombectomyRapidWhen systemic lysis high risk or ineffectiveBleeding; expertise required; outpatient use
Enoxaparin (LMWH)Xa>IIa inhibitionHoursPreferred initial AC in many stable cases; cancer VTEAvoid severe renal failure; outpatient use
Apixaban/RivaroxabanDirect factor Xa inhibitionHoursFirst-line for most stable PE/DVTBleeding; interactions; outpatient use
Alteplase (systemic)Plasminogen activation (fibrinolysis)RapidMassive PE with shock or arrestICH/major bleed; contraindications; outpatient use
Unfractionated heparin (IV)Antithrombin-mediated Xa/IIa inhibitionImmediateInitial AC when lysis/cath possible or renal failureBleeding, HIT; monitor aPTT; outpatient use

Prognosis / Complications

  • Depends on severity/oxygenation; respiratory failure risk

Patient Education / Counseling

  • Explain red flags and when to seek emergent care.
  • Reinforce medication adherence and follow-up plan.

References

  1. ESC/ACEP PE Outpatient Pathways — Link