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

Abstract

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.

Analysis of cerebral Interleukin-6 and tumor necrosis factor alpha patterns following different ventilation strategies during cardiac arrest in pigs

“…In our trial, we tested three different ventilatory interventions during cardiac arrest, further examining the influence of more nuanced inspiratory pressure settings on brain physiology and overall outcome post-ROSC. This continues a series of original research projects specifically targeting sophisticated novel ventilation modes and their effects on tissue inflammation, cardiac output and lung physiology ( Renz et al, 2022 ; Ruemmler et al, 2018 ; Ruemmler et al, 2021 ; Ruemmler et al, 2020 ). The chest-compression synchronized ventilation mode in particular showed promising results in previous studies regarding oxygenation and potential end-organ perfusion improvement ( Kill et al, 2015 ; Kill et al, 2009 ).…”

“…The general trial set-up up to the intervention was described in detail before ( Renz et al, 2022 ). In short, the animals were anesthetized, intubated and instrumented with intravascular catheters.…”

Ultra-low tidal volume ventilation during cardiopulmonary resuscitation shows no mitigating effect on pulmonary end-organ damage compared to standard ventilation: insights from a porcine model

“…MIGET is a technique that allows us to look more closely at lung function in animal models, specifically the ventilation/ perfusion (V/Q) ratio and the shunt fraction of cardiac output. Previously published trials [3,24,25] have validated the application of MIGET technology during CPR, which can offer supplementary insights into circulation and ventilation impairment during CPR.…”

The Influence of Ultra-Low Tidal Volume Ventilation during Cardiopulmonary Resuscitation on Renal and Hepatic End-Organ Damage in a Porcine Model

“…Even so, the chosen porcine ventricular fibrillation model is well established [ 22 , 23 ] and reliably reproducible [ 9 ]. In previous studies, this experimental setting could be used to investigate the effects of different ventilation strategies on hemodynamic parameters and ventilation-associated end-organ damage during CPR [ 24 , 25 ]. The juvenile pig is particularly suitable because its anatomy, physiology, and pathophysiological reactions are comparable to those of humans [ 26 , 27 ]; porcine lungs, in particular, are ideal for ventilation interventions because they are similar in size to the human lung [ 26 ].…”