Background: Invasive ventilation during cardiopulmonary resuscitation (CPR) is very complex due to unique thoracic pressure conditions. Current guidelines do not provide specific recommendations for ventilation during ongoing chest compressions regarding positive end-expiratory pressure (PEEP). This trial examines the cardiopulmonary effects of PEEP application during CPR. Methods: Forty-two German landrace pigs were anaesthetised, instrumented, and randomised into six intervention groups. Three PEEP levels (0, 8, and 16 mbar) were compared in high standard and ultralow tidal volume ventilation. After the induction of ventricular fibrillation, mechanical chest compressions and ventilation were initiated and maintained for thirty minutes. Blood gases, ventilation/perfusion ratio, and electrical impedance tomography loops were taken repeatedly. Ventilation pressures and haemodynamic parameters were measured continuously. Postmortem lung tissue damage was assessed using the diffuse alveolar damage (DAD) score. Statistical analyses were performed using SPSS, and p values <0.05 were considered significant. Results: The driving pressure (Pdrive) showed significantly lower values when using PEEP 16 mbar than when using PEEP 8 mbar (p = 0.045) or PEEP 0 mbar (p < 0.001) when adjusted for the ventilation mode. Substantially increased overall lung damage was detected in the PEEP 0 mbar group (vs. PEEP 8 mbar, p = 0.038; vs. PEEP 16 mbar, p = 0.009). No significant differences in mean arterial pressure could be detected. Conclusion: The use of PEEP during CPR seems beneficial because it optimises ventilation pressures and reduces lung damage without significantly compromising blood pressure. Further studies are needed to examine long-term effects in resuscitated animals.

Background: Invasive ventilation during cardiopulmonary resuscitation (CPR) is very complex due to unique thoracic pressure conditions. Current guidelines do not provide specific recommendations for ventilation during ongoing chest compressions. This trial examines the cardiopulmonary effects of PEEP application during CPR. Three PEEP levels were compared in high (IPPV) and ultralow tidal volume ventilation (ULTVV).Materials and methods: Forty-two German landrace pigs were anesthetized, instrumented, and randomized into six intervention groups: PEEP 0, 8, and 16 mbar with IPPV or ULTVV. After the induction of ventricular fibrillation, mechanical chest compressions and ventilation were initiated. Blood gases, micropore membrane inlet mass spectrometry facilitated multiple inert gas elimination technique (MMIMS-MIGET) samples and electrical impedance tomography (EIT) loops were taken. Ventilation pressures and hemodynamic parameters were measured continuously. Postmortem lung tissue damage was assessed using the diffuse alveolar damage (DAD) score. Statistical analyses were performed using SPSS, and p values ​​<0.05 were considered significant.Results: The driving pressure (Pdrive) showed significantly lower values when using PEEP 16 mbar than when using PEEP 8 mbar (p=0.045) or PEEP 0 mbar (p<0.001) when adjusted for the ventilation mode. When not using PEEP, considerable overall lung damage was detected in the PEEP 0 mbar group (vs. PEEP 8 mbar, p=0.038; vs. PEEP 16 mbar, p=0.009) when adjusted for the ventilation mode. No significant differences between the groups occurred in the mean arterial pressure, even when using high PEEP levels.Conclusion: The use of PEEP during CPR seems beneficial because it optimizes ventilation pressures as well as reduces lung damage without significantly compromising blood pressure. Further studies are needed to examine long-term effects in resuscitated animals.