What is the treatment for pulmonary embolism?

Treatment of Pulmonary Embolism

Immediate anticoagulation is the cornerstone of PE treatment, with the specific approach determined by hemodynamic stability: high-risk PE requires immediate systemic thrombolysis plus unfractionated heparin, intermediate-risk PE uses LMWH or fondaparinux, and low-risk PE can be managed with LMWH or direct oral anticoagulants. 1

Risk Stratification Framework

Risk stratification must be performed immediately to guide treatment intensity 1:

• High-risk PE: Shock or hypotension present 1
• Intermediate-risk PE: Hemodynamically stable but with right ventricular dysfunction 1
• Low-risk PE: Hemodynamically stable without right ventricular dysfunction 1

High-Risk (Massive) PE Management

Immediate Actions

Systemic thrombolytic therapy is a Class I recommendation and should be administered immediately unless contraindicated 1, 2:

• Initiate unfractionated heparin (UFH) with weight-adjusted bolus (80 U/kg or 5,000-10,000 units) followed by continuous infusion at 18 U/kg/h, adjusted to maintain aPTT 1.5-2.5 times control 1
• Administer alteplase 50 mg IV bolus immediately in deteriorating patients 2
• Provide supplemental oxygen to correct hypoxemia (target SaO2 >90%) 1, 2
• Use vasopressors (norepinephrine and/or dobutamine) to correct hypotension 1

Critical Pitfall

Avoid aggressive fluid challenges as they worsen right ventricular failure 2. Hypotension may actually improve with preload reduction or gentle diuresis 3.

Alternative Interventions

If thrombolysis is contraindicated or fails 1, 4:

• Surgical pulmonary embolectomy is the recommended alternative 4
• Emergency thoracotomy or femorofemoral cardiopulmonary bypass for full cardiac arrest 3

Intermediate-Risk (Submassive) PE Management

Initial Anticoagulation

LMWH or fondaparinux is preferred over UFH for intermediate-risk patients 1:

• These agents avoid the nonspecific plasma protein binding that causes heparin resistance and high intersubject variability seen with UFH 5
• Continue parenteral anticoagulation for 5-10 days with overlap to oral anticoagulation 6

Escalation Criteria

Thrombolysis may be considered in selected intermediate-risk patients with clinical deterioration 4. Monitor closely for:

• Worsening hypoxemia despite oxygen supplementation 2
• Hemodynamic deterioration despite anticoagulation 2
• Development of right ventricular failure 4

Low-Risk PE Management

Anticoagulation Options

Direct oral anticoagulants (NOACs) are preferred for most low-risk patients 4:

• Rivaroxaban: FDA-approved for treatment of PE 7
• Apixaban: FDA-approved for treatment of PE 8
• Vitamin K antagonists (target INR 2.5) are an alternative 4

Contraindications to NOACs

NOACs should not be used in 1:

• Severe renal impairment
• Pregnancy and lactation
• Antiphospholipid antibody syndrome

Outpatient Management

Early discharge and home treatment should be considered for carefully selected low-risk patients with proper outpatient care arrangements 1.

Respiratory Support Algorithm

Oxygen Escalation Strategy

Progress through oxygen delivery methods based on response 2:

1. Conventional oxygen supplementation for SaO2 <90% 2
2. High-flow oxygen via nasal cannula if conventional oxygen insufficient 2
3. Non-invasive ventilation if high-flow oxygen fails 2
4. Invasive mechanical ventilation only for extreme instability 2

Mechanical Ventilation Parameters

If intubation becomes necessary 2:

• Use tidal volumes approximately 6 mL/kg lean body weight 2
• Keep end-inspiratory plateau pressure <30 cm H2O 2
• Apply positive end-expiratory pressure cautiously (positive pressure worsens RV failure) 2
• Avoid anesthetic drugs causing hypotension 2

Refractory Hypoxemia

Consider right-to-left shunting through patent foramen ovale as a cause of refractory hypoxemia 2.

Special Considerations

IVC Filter Placement

IVC filters should only be considered in 1:

• Absolute contraindications to anticoagulation
• PE recurrence despite therapeutic anticoagulation

IVC filters are not routinely recommended 2.

Duration of Anticoagulation

• Initial treatment: Minimum 5 days parenteral anticoagulation for pediatric patients transitioning to oral agents 7
• Extended therapy: After completing at least 6 months of initial treatment, consider continued anticoagulation for recurrence risk reduction 7, 8

Follow-Up Protocol

Routinely re-evaluate patients 3-6 months after acute PE 4:

• Implement integrated care model for hospital-to-ambulatory transition 4
• Refer patients with persistent symptoms or mismatched perfusion defects beyond 3 months to pulmonary hypertension expert centers 4

Critical Treatment Pitfalls to Avoid

Delaying thrombolysis in hemodynamically unstable patients is associated with increased mortality 2. Other common errors include:

• Failing to achieve adequate anticoagulant response (aPTT >1.5 times control), which increases recurrent VTE risk to 25% 6
• Delaying escalation of oxygen therapy when conventional supplementation insufficient 2
• Using aggressive fluid challenges in patients with RV dysfunction 2
• Failing to recognize hemodynamic deterioration as indication for escalation from anticoagulation to reperfusion therapy 2