Halsey J H
Department of Neurology, University of Alabama Medical Center, Birmingham 35294.
Stroke. 1990 Nov;21(11):1573-8. doi: 10.1161/01.str.21.11.1573.
This study assesses the problem of transcranial Doppler recording failure and seeks to determine the extent to which this can be ameliorated by increased emitted power. We hypothesized that waveform intensity is directly related to the rate and quality of successful recording and may be compared quantitatively among groups of patients. Among a large group of patients recorded at 800 mW/cm2 emitted power, intensity was strongest in white men, weakest in black women, and intermediate in black men and white women. It declined with age in women of either race, but not in men of either race. Analysis of the effect of emitted power on intensity predicted that significant numbers of waveforms recorded at 800 mW/cm2 could not be recorded at the current clinical standards of 100 mW/cm2, the difference being most pronounced in elderly black women. Temporal bone window thickness measured in a series of adult cadaver skulls was least in white men, greatest in black women, and intermediate in black men and white women. The findings of this study support the hypothesis that temporal bone window thickness is an important determinant of recording difficulty and suggest that increased emitted power can significantly increase successful recording, particularly in black and elderly patients. Increased power alone, however, cannot completely solve the recording problem within safe limits.
本研究评估经颅多普勒记录失败的问题，并试图确定增加发射功率可在多大程度上改善这一问题。我们假设波形强度与成功记录的速率和质量直接相关，并且可以在患者组之间进行定量比较。在以800 mW/cm²发射功率记录的一大组患者中，波形强度在白人男性中最强，在黑人女性中最弱，在黑人男性和白人女性中居中。在任何一个种族的女性中，波形强度都随年龄下降，但在任何一个种族的男性中则不然。对发射功率对波形强度影响的分析预测，按照当前100 mW/cm²的临床标准，在800 mW/cm²记录的大量波形将无法记录，这种差异在老年黑人女性中最为明显。在一系列成年尸体头骨中测量的颞骨窗厚度，在白人男性中最小，在黑人女性中最大，在黑人男性和白人女性中居中。本研究结果支持以下假设：颞骨窗厚度是记录难度的一个重要决定因素，并表明增加发射功率可显著提高成功记录的几率，尤其是在黑人和老年患者中。然而，仅增加功率并不能在安全范围内完全解决记录问题。
