Mechanical ventilation to alter and improve respiratory gases is a fundamental feature of critical care and intraoperative anesthesia management. The range of inspired O2 and expired CO2 during patient management can significantly deviate from values in the healthy awake state. It has long been appreciated that hyperoxia can have deleterious effects on organs, especially the lung and retina. Recent work shows intraoperative end-tidal (ET) CO2 management influences the incidence of perioperative neurocognitive disorder (POND). The interaction of O2 and CO2 on cerebral blood flow (CBF) and oxygenation with alterations common in the critical care and operating room environments has not been well studied. We examine the effects of controlled alterations in both ET O2 and CO2 on cerebral blood flow (CBF) in awake adults using blood oxygenation level-dependent (BOLD) and pseudo-continuous arterial spin labeling (pCASL) MRI. Twelve healthy adults had BOLD and CBF responses measured to alterations in ET CO2 and O2 in various combinations commonly observed during anesthesia. Dynamic alterations in regional BOLD and CBF were seen in all subjects with expected and inverse brain voxel responses to both stimuli. These effects were incremental and rapid (within seconds). The most dramatic effects were seen with combined hyperoxia and hypocapnia. Inverse responses increased with age suggesting greater risk. Human CBF responds dramatically to alterations in ET gas tensions commonly seen during anesthesia and in critical care. Such alterations may contribute to delirium following surgery and under certain circumstances in the critical care environment. ClincialTrials.gov NCT02126215 for some components of the study. First registered April 29, 2014.

中文翻译：

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Brain BOLD MRI O2 和 CO2 压力测试：对手术后围手术期神经认知障碍的影响

改变和改善呼吸气体的机械通气是重症监护和术中麻醉管理的基本特征。患者管理期间吸入的 O2 和呼出的 CO2 的范围可能显着偏离健康清醒状态下的值。人们早就意识到高氧会对器官，尤其是肺和视网膜产生有害影响。最近的工作表明，术中呼气末 (ET) CO2 管理会影响围手术期神经认知障碍 (POND) 的发生率。O2 和 CO2 对脑血流量 (CBF) 和氧合的相互作用以及重症监护和手术室环境中常见的改变尚未得到很好的研究。我们使用血氧水平依赖性 (BOLD) 和伪连续动脉自旋标记 (pCASL) MRI 检查 ET O2 和 CO2 的受控改变对清醒成人脑血流 (CBF) 的影响。12 名健康成年人对 ET CO2 和 O2 的变化进行了 BOLD 和 CBF 反应，这些反应在麻醉期间常见的各种组合中观察到。在对两种刺激具有预期和反向脑体素反应的所有受试者中都观察到区域 BOLD 和 CBF 的动态变化。这些影响是渐进的和快速的（在几秒钟内）。最显着的影响出现在高氧和低碳酸血症的组合中。逆反应随着年龄的增长而增加，表明风险更大。人类 CBF 对麻醉和重症监护期间常见的 ET 气体张力变化有显着反应。这种改变可能会导致手术后和在重症监护环境中的某些情况下出现谵妄。ClincialTrials.gov NCT02126215 用于研究的某些组成部分。2014 年 4 月 29 日首次注册。