Czosnyka M, Richards H, Pickard J D, Harris N, Iyer V
Academic Neurosurgery Unit, Addenbrooke's Hospital, Cambridge, UK.
Ultrasound Med Biol. 1994;20(4):391-9. doi: 10.1016/0301-5629(94)90008-6.
Carotid arterial blood pressure and blood flow velocity in the basilar artery were studied in nine New Zealand rabbits under general anaesthesia. The cerebrovascular impedances for mean and maximal flow velocity were defined as the ratios of the respiratory and pulse waveforms of arterial blood pressure and blood flow velocities. The absolute values of these impedances were expressed and analysed as functions of frequency. Both functions decreased as frequency increased, demonstrating that a pulsatile blood movement need a lower energy expenditure than a continuous one. A minimum absolute value of impedance for flow velocity mean was found near 2.5-4 Hz in each rabbit. The impedance for mean flow velocity could be modelled by a second-order circuit, whereas the distribution of impedance for the maximal velocity had a more uniform character and could be approximated by a first-order model. A method of assessment of changes in cerebrovascular resistance using frequency properties of calculated impedance was proposed.
在全身麻醉下，对9只新西兰兔的颈动脉血压和基底动脉血流速度进行了研究。将平均血流速度和最大血流速度的脑血管阻抗定义为动脉血压和血流速度的呼吸波与脉搏波的比值。这些阻抗的绝对值作为频率的函数进行表示和分析。随着频率增加，这两个函数均下降，表明脉动性血液流动比连续性血液流动需要更低的能量消耗。在每只兔子中，均在2.5 - 4Hz附近发现了血流速度平均值的最小阻抗绝对值。平均血流速度的阻抗可用二阶电路建模，而最大速度的阻抗分布具有更均匀的特性，可用一阶模型近似。提出了一种利用计算阻抗的频率特性评估脑血管阻力变化的方法。
