Knappertz V A, Rothacher G, Sievers C, Krämer G, Kübler A, Lehnert H, Tegeler C H
Neurologische Klinik und Poliklinik, Johannes Gutenberg-Universität, Mainz, Germany.
J Neuroimaging. 1994 Jul;4(3):137-40. doi: 10.1111/jon199443137.
Transcranial Doppler ultrasonography can monitor changes in intracranial blood flow velocity over time in a variety of experimental and clinical settings with excellent temporal resolution. Alterations in arterial carbon dioxide pressure exert a profound influence on blood flow velocity. Such changes exhibit important individual fluctuation depending on respiratory status. This limits the ability of transcranial Doppler to accurately study subtle changes in blood flow velocity, independent of the respiratory state of the subject. Suggested here is a method to control for the respiration artifact on blood flow velocity. The middle cerebral artery of 7 healthy male volunteers was studied with transcranial Doppler under resting conditions, monitoring end-tidal carbon dioxide concentration and blood flow velocity. Hyperventilation was performed both voluntarily and with pharmacological induction by human corticotropin-releasing hormone. These studies were carried out both with and without the use of counterregulation of the end-tidal carbon dioxide concentration via a respiration unit, with an adjustable carbon dioxide-oxygen gas supply preventing significant changes in end-tidal carbon dioxide. The blood flow velocity in the middle cerebral artery during maximal voluntary hyperventilation decreased from baseline values of 100% to 44.4 +/- 4.3% (a 55.6% decrease), and with human corticotropin-releasing hormone-induced involuntary hyperventilation, to 65.1 +/- 5.3% (a 34.9% decrease). With the control method, blood flow velocities during voluntary and pharmacological hyperventilation were 100 +/- 1.6% and 100 +/- 2.8%, respectively. This method allows for control of respiration-induced artifacts during transcranial Doppler monitoring, and can be used to assess the effect of direct or indirect blood flow velocity stimuli independent of respiratory status.
经颅多普勒超声检查能够在各种实验和临床环境中，以出色的时间分辨率监测颅内血流速度随时间的变化。动脉二氧化碳分压的改变对血流速度有深远影响。此类变化因呼吸状态而异，呈现出重要的个体波动。这限制了经颅多普勒在不考虑受试者呼吸状态的情况下准确研究血流速度细微变化的能力。本文提出一种控制血流速度呼吸伪影的方法。对7名健康男性志愿者的大脑中动脉在静息状态下进行经颅多普勒研究，监测呼气末二氧化碳浓度和血流速度。通过自愿过度换气以及使用人促肾上腺皮质激素释放激素进行药物诱导过度换气。这些研究在使用和不使用通过呼吸装置对呼气末二氧化碳浓度进行反调节的情况下进行，该呼吸装置具有可调节的二氧化碳 - 氧气供应，可防止呼气末二氧化碳发生显著变化。在最大程度自愿过度换气期间，大脑中动脉的血流速度从基线值的100%降至44.4±4.3%（降低了55.6%），而在人促肾上腺皮质激素释放激素诱导的非自愿过度换气时，降至65.1±5.3%（降低了34.9%）。采用控制方法时，自愿和药物诱导过度换气期间的血流速度分别为100±1.6%和100±2.8%。该方法可在经颅多普勒监测期间控制呼吸引起的伪影，并可用于评估独立于呼吸状态的直接或间接血流速度刺激的效果。
