What is the role of Positive End-Expiratory Pressure (PEEP) in managing cardiac arrest?

Role of PEEP in Cardiac Arrest Management

Routine hyperventilation with excessive PEEP should be avoided during cardiac arrest resuscitation as it may worsen hemodynamics, while a modest PEEP of 5-10 cmH2O may be beneficial after return of spontaneous circulation (ROSC) to prevent atelectasis and improve oxygenation. 1

During Active Resuscitation (CPR)

Potential Harms of PEEP During CPR

• Hemodynamic compromise: High PEEP levels during CPR can:
  • Decrease venous return to the heart
  • Reduce cardiac preload
  • Impair coronary perfusion pressure
  • Exacerbate hypotension in already compromised circulation 1

Auto-PEEP Considerations

• Auto-PEEP (intrinsic PEEP) can develop during CPR, especially with:
  • Excessive ventilation rates
  • Obstructive lung disease
  • Inadequate expiratory time 1
• Auto-PEEP can lead to:
  • Gas trapping
  • Decreased venous return
  • Reduced cardiac output
  • Impaired effectiveness of chest compressions 1

Management During CPR

• For patients in cardiac arrest with suspected auto-PEEP:
  • Consider brief disconnection from the ventilator circuit to allow PEEP to dissipate
  • Compression of the chest wall to relieve air-trapping can be effective (Class IIa, LOE C) 1
  • Use slower respiratory rates with smaller tidal volumes (6-8 mL/kg) 1

After Return of Spontaneous Circulation (ROSC)

Recommended PEEP Strategy Post-ROSC

• After ROSC, a lung-protective ventilation strategy is recommended:
  • PEEP of 5-10 cmH2O to maintain alveolar inflation
  • Higher PEEP (>10 cmH2O) may be beneficial to prevent pulmonary edema and atelectasis in ECPR patients 1
  • Target tidal volumes of 6-8 mL/kg predicted body weight 1, 2

Benefits of Appropriate PEEP Post-ROSC

• Prevents alveolar collapse
• Improves oxygenation
• Reduces ventilator-associated lung injury
• May reduce incidence of pulmonary complications 2

Monitoring and Adjustment

• Monitor for signs of hemodynamic compromise with PEEP
• Assess for adequate oxygenation (target SaO2 92-97%) 1
• Avoid hyperventilation with hypocapnia as it may worsen global brain ischemia through cerebral vasoconstriction (Class III, LOE C) 1

Special Considerations

Asthma and Obstructive Disease

• In patients with asthma or obstructive lung disease who develop cardiac arrest:
  • Auto-PEEP is a common cause of deterioration
  • Use lower respiratory rates and tidal volumes
  • Allow longer expiratory times (inspiratory to expiratory ratio 1:4 or 1:5)
  • Consider applying low levels of external PEEP (≤5 cmH2O) to counterbalance auto-PEEP 1

Experimental Evidence

• Animal studies suggest that continuous application of PEEP (5 cmH2O) during and after CPR may have beneficial effects on survival 3, 4
• Recent experimental evidence indicates that 10 cmH2O PEEP during prolonged CPR may be used with either continuous or 30:2 compression-to-ventilation ratios 5

Practical Recommendations

1. During active CPR:

   • Minimize PEEP (0-5 cmH2O) to avoid hemodynamic compromise
   • Use lower ventilation rates to prevent auto-PEEP
   • Consider brief disconnection from ventilator if auto-PEEP is suspected

2. After ROSC:

   • Apply moderate PEEP (5-10 cmH2O)
   • Use lung-protective ventilation strategy (6-8 mL/kg tidal volume)
   • Avoid hyperventilation
   • Target normocapnia

3. For patients with obstructive lung disease:

   • Be vigilant for auto-PEEP
   • Use longer expiratory times
   • Consider external PEEP to counterbalance auto-PEEP

By carefully managing PEEP during and after cardiac arrest, clinicians can optimize cardiopulmonary interactions and potentially improve patient outcomes.