Department of Anesthesiology, Perioperative and Pain Medicine, Max Rady College of Medicine, University of Manitoba, 2nd Floor, Harry Medovy House, 671 William Ave., Winnipeg, MB, R3E 0Z2, Canada.
Canada North Concussion Network, .
Crit Care. 2020 Mar 4;24(1):76. doi: 10.1186/s13054-020-2800-3.
Mechanical ventilation to alter and improve respiratory gases is a fundamental feature of critical care and intraoperative anesthesia management. The range of inspired O and expired CO 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) CO management influences the incidence of perioperative neurocognitive disorder (POND). The interaction of O and CO 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 O and CO 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 CO and O 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.
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。在患者管理过程中，吸入的 O 和呼出的 CO 的范围可能与健康清醒状态下的值有很大的偏差。长期以来，人们一直认为高氧会对器官，特别是肺和视网膜产生有害影响。最近的研究表明，术中呼气末（ET）CO 管理会影响围手术期认知障碍（POND）的发生率。O 和 CO 对脑血流（CBF）和氧合的相互作用，以及在重症监护室和手术室环境中常见的变化，尚未得到很好的研究。
我们使用血氧水平依赖（BOLD）和伪连续动脉自旋标记（pCASL）MRI，检查在清醒成年人中，控制 ET O 和 CO 的变化对脑血流（CBF）的影响。12 名健康成年人在各种常见的麻醉期间，测量了 ET CO 和 O 变化对脑血流（CBF）的 BOLD 和 CBF 反应。
所有受试者都观察到了区域 BOLD 和 CBF 的动态变化，对两种刺激都有预期和反向的脑体素反应。这些影响是递增的和快速的（在几秒钟内）。最显著的影响是在高氧和低碳酸血症联合作用下出现的。随着年龄的增长，反向反应增加，提示风险增加。
人类 CBF 对麻醉和重症监护中常见的 ET 气体张力的变化反应剧烈。这些变化可能导致手术后谵妄，并在某些情况下导致重症监护环境中的并发症。
ClincialTrials.gov NCT02126215，用于研究的一些部分。首次于 2014 年 4 月 29 日注册。
