Hammervold Rønnaug, Beqiri Erta, Smielewski Peter, Storm Benjamin S, Nielsen Erik W, Guérin Claude, Frisvold Shirin K
Department of Anaesthesia and Intensive Care, Nordland Hospital Trust, Bodø, Norway.
Department of Clinical Medicine, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway.
Front Med (Lausanne). 2025 Jan 7;11:1501284. doi: 10.3389/fmed.2024.1501284. eCollection 2024.
Positive end-expiratory pressure (PEEP) and prone positioning can improve gas exchange by promoting uniform lung aeration. However, elevated ventilation pressures may increase intracranial pressure (ICP) and disrupt cerebral autoregulation. This study investigated the effects of PEEP on ICP and cerebral autoregulation in a porcine model with healthy lungs and normal ICP, comparing prone and supine positions. Cerebral autoregulation was assessed through cerebrovascular reactivity using the pressure reactivity index (PRx). We also explored whether other baseline variables influenced potential variances in ICP and PRx.
Twelve anesthetized pigs were randomized to begin in either supine or prone position, across PEEP of 5, 10, 15, and 20 cmHO. Continuous monitoring included esophageal pressure to calculate end-inspiratory and end-expiratory transpulmonary pressures. The ICM+ software (University of Cambridge Enterprise, Cambridge, United Kingdom) was used for high-resolution data collection, signal processing and ICP curve analysis. Linear mixed-effects models and ANOVA were used to analyze changes in ICP and PRx and the influence of position. An exploratory correlation analysis was conducted on baseline variables potentially related to the ICP increase.
Mean ICP increase was 1.0 mmHg ± 0.9 at 10 cmHO PEEP, 2.0 mmHg ± 1.7 at 15 cmHO PEEP, and 3.1 mmHg ± 1.6 at 20 cmHO PEEP compared to a baseline PEEP of 5 cmHO ( < 0.001). The effect of PEEP increase on ICP was not influenced by body position. PRx remained unaffected by PEEP. PEEP-induced increases in ICP were higher in cases of higher baseline ICP, higher central venous pressure, lower respiratory system elastance and lower end-inspiratory and end-expiratory transpulmonary pressures.
Increasing PEEP elevates ICP regardless of body position without adversely affecting cerebral autoregulation in a healthy porcine model. Baseline ICP, central venous pressure, respiratory system elastance and end-inspiratory and end-expiratory transpulmonary pressure may influence the magnitude of ICP changes.
呼气末正压（PEEP）和俯卧位可通过促进肺通气均匀分布来改善气体交换。然而，升高的通气压力可能会增加颅内压（ICP）并破坏脑自动调节功能。本研究在肺部健康且颅内压正常的猪模型中，比较俯卧位和仰卧位，探究PEEP对ICP和脑自动调节的影响。通过使用压力反应指数（PRx）评估脑血管反应性来评估脑自动调节功能。我们还探讨了其他基线变量是否会影响ICP和PRx的潜在差异。
将12只麻醉猪随机分为仰卧位或俯卧位起始组，PEEP分别设置为5、10、15和20 cmH₂O。连续监测包括食管压力，以计算吸气末和呼气末跨肺压。使用ICM+软件（英国剑桥大学企业）进行高分辨率数据采集、信号处理和ICP曲线分析。采用线性混合效应模型和方差分析来分析ICP和PRx的变化以及体位的影响。对可能与ICP升高相关的基线变量进行探索性相关分析。
与5 cmH₂O的基线PEEP相比，在10 cmH₂O PEEP时平均ICP升高1.0 mmHg±0.9，在15 cmH₂O PEEP时升高2.0 mmHg±1.7，在20 cmH₂O PEEP时升高3.1 mmHg±1.6（P<0.001）。PEEP升高对ICP的影响不受体位影响。PRx不受PEEP影响。在基线ICP较高、中心静脉压较高、呼吸系统弹性较低以及吸气末和呼气末跨肺压较低的情况下，PEEP诱导的ICP升高更高。
在健康猪模型中，无论体位如何，增加PEEP都会升高ICP，且不会对脑自动调节产生不利影响。基线ICP、中心静脉压、呼吸系统弹性以及吸气末和呼气末跨肺压可能会影响ICP变化的幅度。
