Clough Rebecca H, Panerai Ronney B, Ladthavorlaphatt Kannaphob, Robinson Thompson G, Minhas Jatinder S
Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom.
NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, United Kingdom.
J Appl Physiol (1985). 2024 Oct 1;137(4):892-902. doi: 10.1152/japplphysiol.00851.2023. Epub 2024 Aug 15.
Arterial carbon dioxide ([Formula: see text]) and posture influence the middle (MCAv) and posterior (PCAv) cerebral artery blood velocities, but there is paucity of data about their interaction and need for an integrated model of their effects, including dynamic cerebral autoregulation (dCA). In 22 participants (11 males, age 30.2 ± 14.3 yr), blood pressure (BP, Finometer), dominant MCAv and nondominant PCAv (transcranial Doppler ultrasound), end-tidal CO (EtCO, capnography), and heart rate (HR, ECG) were recorded continuously. Two recordings (R) were taken when the participant was supine (R1, R2), two taken when the participant was sitting (R3, R4), and two taken when the participant was standing (R5, R6). R1, R3, and R5 consisted of 3 min of 5% CO through a mask and R2, R4, and R6 consisted of 3 min of paced hyperventilation. The effects of [Formula: see text] were expressed with a logistic curve model (LCM) for each parameter. dCA was expressed by the autoregulation index (ARI), derived by transfer function analysis. Standing shifted LCM to the left for MCAv ( < 0.001), PCAv ( < 0.001), BP ( = 0.03), and ARI ( = 0.001); downward for MCAv and PCAv (both < 0.001), and upward for HR ( < 0.001). For BP, LCM was shifted downward by sitting and standing ( = 0.024). For ARI, the hypercapnic range of LCM was shifted upward during standing ( < 0.001). A more complete mapping of the combined effects of posture and arterial CO on the cerebral circulation and peripheral variables can be obtained with the LCM over a broad physiological range of EtCO values. Data from supine, sitting, and standing postures were measured. Modeling the data with logistic curves to express the effects of CO reactivity on middle cerebral artery blood velocity (MCAv), posterior cerebral artery blood velocity (PCAv), heart rate, blood pressure (BP), and the autoregulation index (ARI), provided a more comprehensive approach to study the interaction of arterial CO with posture than in previous studies. Above all, shifts of the logistic curve model with changes in posture have shown interactions with [Formula: see text] that have not been previously demonstrated.
动脉血二氧化碳分压（[公式：见正文]）和体位会影响大脑中动脉（MCAv）和大脑后动脉（PCAv）的血流速度，但关于它们之间相互作用的数据较少，且需要一个综合模型来研究它们的影响，包括动态脑自动调节（dCA）。在22名参与者（11名男性，年龄30.2±14.3岁）中，连续记录血压（BP，Finometer）、优势侧MCAv和非优势侧PCAv（经颅多普勒超声）、呼气末二氧化碳分压（EtCO，二氧化碳描记法）和心率（HR，心电图）。当参与者仰卧时进行两次记录（R1、R2），坐着时进行两次记录（R3、R4），站立时进行两次记录（R5、R6）。R1、R3和R5包括通过面罩吸入5%二氧化碳3分钟，R2、R4和R6包括3分钟的定频过度通气。每个参数的[公式：见正文]效应采用逻辑曲线模型（LCM）表示。dCA通过传递函数分析得出的自动调节指数（ARI）表示。站立使MCAv（<0.001）、PCAv（<0.001）、BP（=0.03）和ARI（=0.001）的LCM向左移动；使MCAv和PCAv向下移动（均<0.001），使HR向上移动（<0.001）。对于BP，坐着和站立时LCM向下移动（=0.024）。对于ARI，站立时LCM的高碳酸血症范围向上移动（<0.001）。在EtCO值的广泛生理范围内，使用LCM可以更完整地描绘体位和动脉二氧化碳对脑循环及外周变量的综合影响。测量了仰卧、坐着和站立体位的数据。用逻辑曲线对数据进行建模，以表达二氧化碳反应性对大脑中动脉血流速度（MCAv）、大脑后动脉血流速度（PCAv）、心率、血压（BP）和自动调节指数（ARI）的影响，为研究动脉二氧化碳与体位的相互作用提供了一种比以往研究更全面操作方法。最重要的是，逻辑曲线模型随体位变化的移动显示出与[公式：见正文]的相互作用，这在以前尚未得到证实。
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