Comparison of different airway pressures in (synchronized) ventilation during cardiopulmonary resuscitation in pigs

The optimal ventilation strategy during cardiopulmonary resuscitation (CPR) remains undetermined. Synchronizing ventilation to chest compressions has been proposed to enhance end-organ perfusion and oxygenation. This study evaluates the pulmonary function and injury in a synchronized ventilation (SV) strategy using lower peak pressure compared to chest compression synchronized ventilation (CCSV) with higher peak pressures and intermittent positive pressure ventilation (IPPV).

35 pigs underwent cardiac arrest, followed by basic and advanced life support with mechanical chest compressions and ventilation according to randomized groups: IPPV (peak pressure (P _peak) 40 mbar), SV (P _peak 20 mbar), and CCSV (P _peak 40 mbar). Arterial blood gases, ventilation-perfusion (V/Q) ratios, and hemodynamics were assessed during CPR and after return of spontaneous circulation (ROSC). Pulmonary histopathology and inflammatory markers (IL-6, TNF-α) were analyzed post-mortem.

During CPR, CCSV demonstrated superior oxygenation compared to SV (p_aO₂: CCSV 190.61 mmHg, SV 96.02 mmHg; p = 0.006), while CCSV and IPPV utilized significant higher airway pressures. SV showed the highest mean arterial pressure. Lactate levels were non-significantly highest in CCSV during CPR. ROSC rates were lower in CCSV (4/10) than in IPPV and SV (both 9/10); all non-ROSC CCSV cases exhibited pneumothoraces. Post-CPR, increased low V/Q and shunt fractions were observed in CCSV and SV exhibited reduced IL-6 expression.

SV resulted in lower oxygenation but utilized lower airway pressures compared with CCSV and IPPV, produced less lactate, and achieved ROSC rates comparable to IPPV with fewer complications compared to CCSV. These findings suggest that SV may represent a viable alternative ventilation strategy during CPR. Further studies are needed to confirm these results.