The CO2 stimulus for cerebrovascular reactivity: Fixing inspired concentrations vs. targeting end-tidal partial pressures
The CO2 stimulus for cerebrovascular reactivity: Fixing inspired concentrations vs. targeting end-tidal partial pressures
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DOI：
10.1177/0271678x16639326
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发表时间：
2016-06-01
影响因子：
6.3
通讯作者：
Fisher, Joseph A.
中科院分区：
文献类型：
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作者：
Fisher, Joseph A.
脑血管反应性（CVR）研究阐明了脑血流调节的生理和病理生理学。一种非侵入性、高空间分辨率的方法使用二氧化碳（CO2）作为血管活性刺激和磁共振技术来估计脑血流反应。CVR被评估为反应变化与刺激变化的比率。寻求刺激的精确控制以最小化测试之间的CVR可变性，并显示功能差异。以潮气末CO2分压为目标的计算机化方法是精确的，但昂贵。更简单，即兴的方法，固定的启发二氧化碳浓度已被推荐为成本较低，因此更广泛地使用。然而，这些方法有缺点，以前没有提出的那些主张他们的使用，或那些雇用他们在他们的研究。作为计算机化方法的开发者之一，我提供了我对这两种方法之间权衡的观点。主要的问题是，声明固定的吸入CO2浓度的精度是误导性的：它并不像所暗示的那样转化为对实际血管活性刺激-动脉CO2分压的精确控制。固有的测试间差异，以及受试者间差异，排除了结果的临床应用。此外，临时方法意味着开发、组装时间和成本的广泛重复，但缺乏统一性和质量控制。提供了方法之间的表格比较。
Cerebrovascular reactivity (CVR) studies have elucidated the physiology and pathophysiology of cerebral blood flow regulation. A non-invasive, high spatial resolution approach uses carbon dioxide (CO2) as the vasoactive stimulus and magnetic resonance techniques to estimate the cerebral blood flow response. CVR is assessed as the ratio response change to stimulus change. Precise control of the stimulus is sought to minimize CVR variability between tests, and show functional differences. Computerized methods targeting end-tidal CO2 partial pressures are precise, but expensive. Simpler, improvised methods that fix the inspired CO2 concentrations have been recommended as less expensive, and so more widely accessible. However, these methods have drawbacks that have not been previously presented by those that advocate their use, or those that employ them in their studies. As one of the developers of a computerized method, I provide my perspective on the trade-offs between these two methods. The main concern is that declaring the precision of fixed inspired concentration of CO2 is misleading: it does not, as implied, translate to precise control of the actual vasoactive stimulus - the arterial partial pressure of CO2. The inherent test-to-test, and therefore subject-to-subject variability, precludes clinical application of findings. Moreover, improvised methods imply widespread duplication of development, assembly time and costs, yet lack uniformity and quality control. A tabular comparison between approaches is provided.