High PEEP Levels during CPR Improve Ventilation without Deleterious Haemodynamic Effects in Pigs

Area of Science:

• Critical Care Medicine
• Cardiopulmonary Physiology
• Anesthesiology

Background:

• Invasive ventilation during cardiopulmonary resuscitation (CPR) presents unique challenges due to thoracic pressure dynamics.
• Current guidelines lack specific recommendations for positive end-expiratory pressure (PEEP) during chest compressions.
• The cardiopulmonary effects of PEEP application during CPR require further investigation.

Purpose of the Study:

• To examine the cardiopulmonary effects of applying varying levels of PEEP during mechanical ventilation in a porcine model of CPR.
• To assess the impact of PEEP on ventilation pressures, blood gases, and lung injury during CPR.
• To determine if PEEP influences hemodynamic stability during CPR.

Main Methods:

• Forty-two pigs were randomized into six groups comparing PEEP levels (0, 8, 16 mbar) with high-standard and ultralow tidal volume ventilation.
• Ventricular fibrillation was induced, followed by 30 minutes of mechanical chest compressions and ventilation.
• Measurements included blood gases, ventilation/perfusion ratio, electrical impedance tomography, ventilation pressures, hemodynamics, and postmortem lung tissue damage (DAD score).

Main Results:

• Driving pressure was significantly lower with PEEP 16 mbar compared to PEEP 8 mbar and 0 mbar.
• Increased overall lung damage (DAD score) was observed in the PEEP 0 mbar group compared to PEEP 8 mbar and 16 mbar groups.
• No significant differences in mean arterial pressure were detected across PEEP groups.

Conclusions:

• Positive end-expiratory pressure (PEEP) application during CPR appears to optimize ventilation pressures and mitigate lung damage.
• PEEP during CPR did not significantly compromise hemodynamic parameters in this study.
• Further research is warranted to evaluate the long-term effects of PEEP in animals that achieve return of spontaneous circulation.