Evaluation of cerebral hemodynamics by transcranial Doppler ultrasonography and its correlation with intracranial pressure in an animal model of intracranial hypertension

ABSTRACT Background: Transcranial Doppler has been tested in the evaluation of cerebral hemodynamics as a non-invasive assessment of intracranial pressure (ICP), but there is controversy in the literature about its actual benefit and usefulness in this situation. Objective: To investigate cerebral blood flow assessed by Doppler technique and correlate with the variations of the ICP in the acute phase of intracranial hypertension in an animal model. Methods: An experimental animal model of intracranial hypertension was used. The experiment consisted of two groups of animals in which intracranial balloons were implanted and inflated with 4 mL (A) and 7 mL (B) for controlled simulation of different volumes of hematoma. The values of ICP and Doppler parameters (systolic [FVs], diastolic [FVd], and mean [FVm] cerebral blood flow velocities and pulsatility index [PI]) were collected during the entire procedure (before and during hematoma simulations and venous hypertonic saline infusion intervention). Comparisons between Doppler parameters and ICP monitoring were performed. Results: Twenty pigs were studied, 10 in group A and 10 in group B. A significant correlation between PI and ICP was obtained, especially shortly after abrupt elevation of ICP. There was no correlation between ICP and FVs, FVd or FVm separately. There was also no significant change in ICP after intravenous infusion of hypertonic saline solution. Conclusions: These results demonstrate the potential of PI as a parameter for the evaluation of patients with suspected ICP elevation.

摘要 背景：经颅多普勒（Transcranial Doppler）已被应用于脑血流动力学评估，作为颅内压（intracranial pressure, ICP）的无创检测手段，但现有文献中关于其在此场景下的实际价值与应用潜力尚存争议。目的：本研究旨在借助多普勒技术评估脑血流量，并在颅内压升高急性期的动物模型中，探讨其与颅内压变化的相关性。方法：本研究采用颅内压升高的实验动物模型。实验将动物分为两组，通过植入颅内球囊并分别注入4mL（A组）与7mL（B组）生理盐水，以可控方式模拟不同体积的颅内血肿。在整个实验流程中（血肿模拟阶段前后以及静脉输注高渗盐水干预期间），同步采集颅内压与多普勒参数数据，包括收缩期脑血流速度（systolic cerebral blood flow velocity, FVs）、舒张期脑血流速度（diastolic cerebral blood flow velocity, FVd）、平均脑血流速度（mean cerebral blood flow velocity, FVm）以及搏动指数（pulsatility index, PI）。随后对多普勒参数与颅内压监测结果进行相关性比较分析。结果：本研究共纳入20头实验猪，A组与B组各10头。研究发现搏动指数（PI）与颅内压（ICP）之间存在显著相关性，尤其在颅内压骤然升高后短期内更为明显。单独分析时，颅内压与FVs、FVd或FVm均未表现出相关性。此外，经静脉输注高渗盐水后，颅内压未出现显著变化。结论：本研究结果表明，搏动指数（PI）可作为疑似颅内压升高患者的评估参数，具备潜在临床应用价值。