What is the best approach for managing a patient with bilateral pulmonary embolisms (PE) in the upper and lower lobes, diagnosed by computed tomography angiography (CTA), in terms of determining whether to treat as an outpatient with anticoagulation therapy or to send to the emergency room for further evaluation and management?

Risk Stratification for Bilateral Pulmonary Embolism: Outpatient vs. Emergency Department Management

For a patient with bilateral PE confirmed on CTA, immediately assess hemodynamic stability and use validated risk stratification tools—hemodynamically stable patients with low-risk scores (PESI Class I-II or sPESI = 0) can be safely treated as outpatients with direct oral anticoagulants, while those with any signs of instability, RV dysfunction, elevated troponin, or intermediate-to-high risk scores require emergency department admission and monitoring. 1, 2

Immediate Assessment: Hemodynamic Stability

The first critical decision point is determining hemodynamic stability:

• High-risk PE (hemodynamically unstable): Patients with systolic blood pressure <90 mmHg, requiring vasopressors, or in shock must be sent immediately to the emergency department for potential reperfusion therapy 1, 2
• Non-high-risk PE (hemodynamically stable): These patients require further risk stratification to determine disposition 1, 2

Risk Stratification Tools for Stable Patients

Use validated clinical decision tools to stratify risk in hemodynamically stable patients:

Pulmonary Embolism Severity Index (PESI) or Simplified PESI (sPESI)

Outpatient candidates must meet ALL of the following criteria 1, 3:

• sPESI score = 0 (or PESI Class I-II)
• No signs of right ventricular dysfunction on imaging or echocardiography 1
• Normal troponin levels 1
• Oxygen saturation ≥90% on room air 1
• No active bleeding or high bleeding risk 1
• No severe renal impairment (if using DOACs) 1
• Adequate social support and ability to comply with follow-up 1

Additional Risk Markers Requiring Hospital Admission

Send to the emergency department if ANY of the following are present 1, 2:

• RV dysfunction on echocardiography or CTPA (RV/LV ratio >1.0) 1, 2
• Positive cardiac biomarkers (troponin elevation) 1
• Heart rate >110 beats/min 1
• Systolic blood pressure 90-100 mmHg (borderline hypotension) 1
• Respiratory rate >30/min 1
• Significant comorbidities (active cancer, severe COPD, heart failure) 1
• Recent surgery or trauma 1
• Pregnancy 1

Outpatient Management Protocol

For carefully selected low-risk patients, outpatient management is safe and effective 1, 4, 3:

Anticoagulation Initiation

• Start a direct oral anticoagulant (DOAC) immediately: Rivaroxaban or apixaban are preferred as they do not require initial parenteral anticoagulation bridging 1, 2, 4
• Rivaroxaban: 15 mg twice daily for 21 days, then 20 mg once daily 1
• Apixaban: 10 mg twice daily for 7 days, then 5 mg twice daily 1, 5
• Do NOT use apixaban in hemodynamically unstable patients or those requiring thrombolysis 5

Follow-up Requirements

Outpatient management requires structured safety-netting 1:

• Telephone contact within 24-48 hours 1
• Clinical review at 7-10 days 1
• Written instructions regarding warning signs (chest pain, dyspnea, syncope, bleeding) 1
• 24-hour emergency contact number 1
• Reassessment at 3-6 months for anticoagulation duration 1

Emergency Department Management

Admit patients with intermediate or high-risk features 1, 2:

Initial Treatment

• Start anticoagulation immediately while diagnostic workup proceeds, unless contraindications exist 2, 6
• Use weight-based unfractionated heparin: 80 units/kg bolus, then 18 units/kg/hour infusion targeting aPTT 1.5-2.5 times control 6
• Alternative: Low molecular weight heparin (LMWH) at therapeutic doses 1

Monitoring Requirements

• Continuous cardiac monitoring for first 24-48 hours due to risk of hemodynamic decompensation 1
• Serial troponin measurements 1
• Repeat echocardiography if clinical deterioration occurs 1

Escalation Criteria

Consider systemic thrombolysis or catheter-directed therapy if 1, 7:

• Hemodynamic deterioration develops despite anticoagulation 1
• Persistent hypotension or shock 1
• Severe RV dysfunction with positive troponin (intermediate-high risk) 1

Common Pitfalls to Avoid

• Never delay anticoagulation while awaiting imaging or admission in intermediate-to-high probability patients—this significantly increases mortality 2, 6
• Do not discharge patients based solely on "bilateral" PE location—the extent of clot burden matters less than hemodynamic impact and RV function 1
• Avoid using clinical gestalt alone—always use validated risk stratification tools (PESI/sPESI) 1, 3
• Do not assume young, otherwise healthy patients are automatically low-risk—still perform formal risk stratification 1
• Recognize that negative preoperative imaging does not exclude intraoperative PE development in high-risk patients 8

Special Populations

Cancer Patients

• Generally require hospital admission due to higher bleeding and recurrence risk 1
• DOACs (rivaroxaban, apixaban, edoxaban) are acceptable alternatives to LMWH 6

Pregnancy

• Requires hospital admission 1
• Use therapeutic LMWH based on early pregnancy weight 1
• Never use DOACs during pregnancy or lactation 1