What is the treatment for bilateral pulmonary emboli?

Treatment of Bilateral Pulmonary Emboli

Initiate immediate anticoagulation with unfractionated heparin (UFH) if the patient is hemodynamically unstable (shock or hypotension), or use low molecular weight heparin (LMWH) if the patient is stable, followed by transition to oral anticoagulation for at least 3 months. 1, 2

Risk Stratification Determines Treatment Intensity

The first critical step is determining hemodynamic stability, as this dictates whether you need aggressive reperfusion therapy or anticoagulation alone 1, 2, 3:

• High-risk PE: Shock or persistent hypotension (systolic BP <90 mmHg or drop ≥40 mmHg for >15 minutes) - requires immediate thrombolysis 1, 2
• Intermediate-risk PE: Hemodynamically stable but with right ventricular dysfunction on echo or CTPA, or elevated cardiac biomarkers - anticoagulation with selective thrombolysis consideration 1, 3
• Low-risk PE: Hemodynamically stable without RV dysfunction - anticoagulation alone, consider early discharge 1, 2

Immediate Anticoagulation Protocol

For High-Risk (Massive) PE:

Start UFH immediately with weight-adjusted bolus of 80 units/kg (or 5,000-10,000 units) followed by continuous infusion of 18 units/kg/hour, adjusted to maintain aPTT 1.5-2.5 times control. 1, 2 UFH is preferred over LMWH in massive PE because it has a shorter half-life and can be rapidly reversed if needed for surgical intervention 1, 2.

For Intermediate or Low-Risk PE:

LMWH or fondaparinux is preferred over UFH for initial parenteral anticoagulation. 1, 3 The advantages include:

• Fixed-dose subcutaneous administration without need for aPTT monitoring 1, 4
• Equal or superior efficacy and safety compared to UFH 1, 4, 5
• Enables outpatient management in selected low-risk patients 1

Common LMWH regimens with longest safety track record include enoxaparin, dalteparin, and nadroparin 5.

Thrombolytic Therapy

Systemic thrombolysis is the first-line treatment for high-risk PE and should be administered immediately unless absolute contraindications exist. 1, 3

Thrombolysis Regimen:

• Alteplase (rtPA): 100 mg over 2 hours, or 50 mg bolus in cardiac arrest 1
• Streptokinase: 250,000 units over 20 minutes, then 100,000 units/hour for 24 hours (plus hydrocortisone to prevent circulatory instability) 1
• Urokinase: 4,400 IU/kg over 10 minutes, then 4,400 IU/kg/hour for 12 hours 1

Do NOT use routine thrombolysis in intermediate or low-risk PE - the bleeding risk outweighs benefit 1. However, rescue thrombolysis is recommended if the patient deteriorates hemodynamically despite anticoagulation 1.

Alternative Reperfusion if Thrombolysis Contraindicated or Failed:

• Surgical pulmonary embolectomy is recommended as first alternative 1, 3
• Percutaneous catheter-directed treatment should be considered as second alternative 1, 3

Transition to Oral Anticoagulation

When oral anticoagulation is initiated, a direct oral anticoagulant (DOAC/NOAC) such as apixaban, rivaroxaban, edoxaban, or dabigatran is preferred over warfarin. 1, 3, 6

DOAC Contraindications (use warfarin instead):

• Severe renal impairment (CrCl <30 mL/min for most DOACs) 1, 7
• Pregnancy and lactation 1
• Antiphospholipid antibody syndrome 1

Warfarin Protocol (if DOAC contraindicated):

• Start 5-10 mg daily for 2 days, then adjust to maintain INR 2.0-3.0 1
• Overlap with heparin for at least 5 days AND until INR ≥2.0 for 24 hours 1
• Monitor INR every 1-2 days initially, then as needed 1

Duration of Anticoagulation

The minimum duration is 3 months for all PE patients. 1, 3 Beyond that:

• Provoked PE (temporary risk factor like surgery, immobilization, trauma): Stop at 3 months 1, 3
• First unprovoked PE: 3-6 months minimum; consider indefinite therapy based on bleeding risk 1, 3
• Recurrent PE or persistent risk factors: Indefinite anticoagulation 1, 3
• Cancer-associated PE: LMWH for at least 6 months, continue as long as cancer is active 3

Special Considerations

Inferior Vena Cava (IVC) Filters:

IVC filters should be considered ONLY in patients with absolute contraindications to anticoagulation or recurrent PE despite therapeutic anticoagulation. 1, 3 Routine use is not recommended 1.

Early Discharge and Outpatient Management:

Carefully selected low-risk PE patients should be considered for early discharge if proper outpatient care and anticoagulation can be provided. 1 This requires:

• No significant breathlessness 1
• No medical or social contraindications 1
• Efficient outpatient anticoagulation protocol in place 1

Common Pitfalls to Avoid:

• Do not delay heparin while awaiting imaging if clinical probability is intermediate or high 1
• Do not use thrombolysis routinely in non-massive PE - bleeding risk exceeds benefit 1
• Do not stop anticoagulation prematurely - this increases thrombotic event risk 7
• Monitor for heparin-induced thrombocytopenia if UFH continued beyond 5 days 1
• Reassess patients at 3-6 months post-PE for persistent dyspnea or functional limitation 3