What is the management of massive pulmonary embolism?

Management of Massive Pulmonary Embolism

Thrombolytic therapy is the first-line treatment for massive pulmonary embolism with hemodynamic instability, and should be administered as early as possible to reduce mortality. 1

Definition and Diagnosis

Massive pulmonary embolism (PE) is defined as PE causing hemodynamic instability with persistent hypotension (systolic BP <90 mmHg for at least 15 minutes), cardiogenic shock, or cardiac arrest not due to other causes.

Rapid Diagnosis:

• CTPA or echocardiography should be performed within 1 hour to diagnose massive PE 2
• Echocardiography can be performed at bedside and shows:
  • Right ventricular dilatation
  • Right heart thrombus (if present)
  • Interventricular septal displacement
• CTPA reliably demonstrates proximal thrombus and acute right ventricular dilatation 2

Initial Management Algorithm

1. Immediate Supportive Care:

   • Oxygen supplementation
   • Intravenous fluid resuscitation
   • Vasopressor support for persistent hypotension
   • Establish invasive arterial access for patients with shock/hypotension 1
   • Maintain right atrial pressure at 15-20 mmHg for maximal right heart filling 1
   • Avoid diuretics and vasodilators 1

2. Anticoagulation:

   • Immediate unfractionated heparin (UFH): 70-80 IU/kg IV bolus (5,000-10,000 units), followed by continuous infusion at 18 IU/kg/hr 2, 3
   • Target aPTT of 1.5-2.5 times control value 1
   • Monitor aPTT 4-6 hours after starting treatment and at least daily thereafter 1

3. Thrombolytic Therapy (First-line treatment for massive PE):

   • Alteplase (tPA): 100 mg IV over 2 hours in stable patients, or 50 mg IV bolus in cardiac arrest/severe deterioration 1
   • Alternative: Tenecteplase as a single weight-based IV bolus:
     • 30 mg for weight <60 kg
     • 35 mg for 60-69 kg
     • 40 mg for 70-79 kg
     • 45 mg for 80-89 kg
     • 50 mg for ≥90 kg 1
   • Suspend heparin during the 2-hour alteplase infusion 1

4. For Patients with Contraindications to Thrombolysis or Failed Thrombolysis:

   • Catheter-directed interventions OR
   • Surgical embolectomy 2

Catheter-Based Interventions

For patients with contraindications to thrombolysis or who remain unstable after thrombolysis:

• Techniques include:

  • Aspiration thrombectomy (81% success rate)
  • Thrombus fragmentation (82% success rate)
  • Rheolytic thrombectomy (75% success rate) 2
  • Combined with local thrombolytic infusion (95% overall success rate) 2

• Procedure approach:

  1. Use 6F femoral venous sheath
  2. Advance 6F angled pigtail catheter into each main pulmonary artery
  3. Inject contrast (30 mL over 2 seconds)
  4. Use UFH 70 IU/kg IV bolus or bivalirudin (0.75 mg/kg IV bolus, then 1.75 mg/kg/h) 2

• Important considerations:

  • Only operators experienced with these techniques should perform catheter-based intervention 2
  • Interventionalists must be comfortable managing cardiogenic shock, bradyarrhythmias, anticoagulation, and cardiac tamponade 2

Advanced Rescue Therapies

For patients with refractory shock despite above measures:

• Extracorporeal Membrane Oxygenation (ECMO):

  • Veno-arterial ECMO can be effective for hemodynamic stabilization in patients with massive PE 4
  • Can serve as a bridge to recovery or definitive therapy 5
  • Survival rates of 76% have been reported even in critically ill patients 4
  • Rapid reversal of multiple organ failure is possible with ECMO as primary therapy 4

• Surgical Embolectomy:

  • Consider for patients who fail thrombolytic therapy or remain unstable after thrombolysis 1
  • Operative mortality ranges from 20-50% 1

Transfer Considerations

• Patients with massive PE who have contraindications to thrombolysis who present to centers unable to offer catheter or surgical embolectomy should be transferred urgently to centers with these capabilities 2
• Only appropriately trained and equipped ambulance crews should transfer these critically ill patients 2, 1
• Institutions with expertise in advanced intervention for PE should be identified in advance 2

Monitoring During Treatment

• Close monitoring of vital signs, oxygen requirements, and signs of bleeding 1
• Serial echocardiography to evaluate right ventricular function 1
• Monitor platelet counts, hematocrit, and occult blood in stool throughout therapy 3
• For patients receiving thrombolysis, monitor for bleeding complications, particularly intracranial hemorrhage 1

Contraindications to Thrombolysis

Absolute contraindications:

• Prior intracranial hemorrhage
• Known structural intracranial cerebrovascular disease
• Active internal bleeding
• Recent stroke
• Recent major surgery or trauma
• Known bleeding diathesis 1

Relative contraindications:

• Chronic, severe, poorly controlled hypertension
• Significant hypertension on presentation
• History of prior ischemic stroke >3 months
• Dementia
• Major surgery (<3 weeks)
• Recent internal bleeding
• Noncompressible vascular punctures
• Pregnancy
• Active peptic ulcer
• Oral anticoagulant therapy 1