What are the survival rates for out-of-hospital cardiac arrests caused by suspected pulmonary embolism?

Survival Rates for Out-of-Hospital Cardiac Arrest Caused by Suspected Pulmonary Embolism

The survival rate for out-of-hospital cardiac arrest caused by suspected pulmonary embolism is extremely poor, with approximately 0-13% of patients surviving to hospital discharge.

Epidemiology and Outcomes

Pulmonary embolism (PE) accounts for approximately 5-13% of unexplained cardiac arrests 1. The outcomes for these patients are significantly worse than for cardiac arrests from other causes:

• Overall survival to hospital discharge is approximately 7.6-7.9% for all out-of-hospital cardiac arrests (OHCAs) 2
• For cardiac arrest specifically caused by PE, survival rates are even lower:
  • Only 13.6% of patients receiving thrombolytic therapy during cardiac arrest for suspected PE survived to hospital discharge in a retrospective study 1
  • Without specialized interventions, the mortality rate for cardiac arrest due to PE approaches 90% 3

Factors Affecting Survival

Several factors influence the survival rates in PE-related cardiac arrests:

1. Early recognition and diagnosis

   • Diagnosis is challenging during cardiac arrest
   • PE is often suspected rather than confirmed during resuscitation

2. Intervention timing

   • Return of spontaneous circulation (ROSC) is achieved in approximately 50% of patients receiving thrombolytic therapy 1
   • However, this does not translate to high survival rates due to post-arrest complications

3. Treatment modalities

   • Conventional CPR alone shows very poor outcomes in PE-related arrest
   • Advanced interventions may improve survival:
     • Thrombolytic therapy during CPR (though evidence is limited)
     • Extracorporeal CPR (ECPR)

Advanced Treatment Options and Their Impact

Thrombolytic Therapy

Thrombolytic therapy during cardiac arrest for suspected PE shows mixed results:

• May improve chances of ROSC 4
• Limited evidence of improved survival to discharge
• Most common regimen is alteplase 100 mg IV push 1
• Bleeding complications appear to be less frequent than feared 4

Extracorporeal CPR (ECPR)

ECPR shows promising results compared to conventional CPR for PE-related arrests:

• ICU survival: 26% with ECPR vs. 5% with conventional CPR
• Favorable neurological outcome: 21% with ECPR vs. 0% with conventional CPR 5

Management Algorithm for Suspected PE-Related Cardiac Arrest

1. Initial management

   • High-quality CPR with minimal interruptions
   • Early defibrillation if shockable rhythm present
   • Consider early administration of unfractionated heparin 6

2. Diagnostic considerations during arrest

   • Point-of-care ultrasound if available (to detect right ventricular strain)
   • Consider mechanical CPR devices to facilitate diagnostic imaging 7

3. Treatment escalation

   • Consider systemic thrombolysis if PE is strongly suspected
   • Standard regimen: alteplase 100 mg over 2 hours, or bolus in arrest situations 6
   • Consider ECPR if available and patient is eligible 5

4. Post-ROSC management

   • Anticoagulation therapy
   • Consider surgical embolectomy if thrombolysis is contraindicated or has failed 6
   • Comprehensive post-arrest care including targeted temperature management

Clinical Pitfalls and Caveats

1. Diagnosis challenges

   • PE is often difficult to confirm during cardiac arrest
   • Consider PE in patients with risk factors or unexplained arrest

2. Treatment decisions

   • Delay in administering thrombolytics may reduce effectiveness
   • Balance between potential benefits of thrombolysis and bleeding risks
   • Surgical embolectomy has high mortality when performed after cardiac arrest 2

3. Resource limitations

   • Advanced therapies like ECPR are not universally available
   • Outcomes may vary significantly based on center expertise and available resources

In conclusion, while survival rates for out-of-hospital cardiac arrest due to PE remain dismal, early recognition, prompt administration of appropriate therapies, and consideration of advanced modalities like thrombolysis and ECPR may improve outcomes in selected patients.