Strohm J, Duffin J, Fisher J A
Department of Medical and Life Sciences, Hochschule Furtwangen University, Germany.
Department of Physiology, University of Toronto, Toronto, ON, Canada M5S 1A8; Department of Anaesthesiology, University of Toronto, and University Health Network, Toronto, ON, Canada.
Respir Physiol Neurobiol. 2014 Jun 15;197:15-8. doi: 10.1016/j.resp.2014.03.003. Epub 2014 Mar 20.
Cerebrovascular reactivity (CVR) assesses the ability of the cerebral vasculature to adjust cerebral blood flow in response to changes in arterial carbon dioxide (CO2), and is used as an indicator of cerebrovascular health. A common method of estimating CVR is to measure the increase in blood flow velocity of the middle cerebral artery (MCAv), using trans-cranial Doppler ultrasound, in response to a CO2 stimulus. We used this method to measure the CVR of 10 subjects in the mornings and evenings of two consecutive days. Mean arterial pressure (MAP) was also measured, and CVR was determined solely from tests where MAP remained unchanged in response to CO2. CVR was measured as the slopes of MCAv responses to a ramp CO2 stimulus fitted with linear regression, and significantly increased from evening to morning each day, with no significant day-to-day differences. We concluded that these measurements of CVR exhibited a circadian rhythm, and were repeatable from one day to the next.
脑血管反应性（CVR）评估脑血管系统响应动脉二氧化碳（CO2）变化来调节脑血流量的能力，并用作脑血管健康的指标。估计CVR的一种常用方法是使用经颅多普勒超声测量大脑中动脉血流速度（MCAv）在CO2刺激下的增加。我们使用这种方法在连续两天的早晨和晚上测量了10名受试者的CVR。还测量了平均动脉压（MAP），并且仅从MAP在CO2刺激下保持不变的测试中确定CVR。CVR以拟合线性回归的斜坡CO2刺激下MCAv反应的斜率来测量，并且每天从晚上到早晨显著增加，没有显著的日间差异。我们得出结论，这些CVR测量显示出昼夜节律，并且可以在一天到下一天重复进行。
