Powers A D, Graeber M C, Smith R R
Department of Neurological Surgery, George Washington University Medical Center, Washington, District of Columbia.
Neurosurgery. 1989 Jun;24(6):884-9. doi: 10.1227/00006123-198906000-00015.
Transcranial Doppler (TCD) ultrasonography was used to perform multiple examinations of 24 patients who sustained cranial injuries, 23 of whom progressed to death. In the 20 of these 23 patients for whom an adequate TCD signal could be obtained, a characteristic reverberating wave form pattern was observed, with an associated net flow velocity of less than 10 cm/sec in all cases. In the last patient in our study group, a reverberating pattern was also identified, however, a net flow velocity of greater than 20 cm/sec was associated with functional recovery. Correlations of neurological function, TCD tracings, and net flow velocities permitted identification of characteristic hemodynamic changes that preceded cerebral circulatory arrest. Early changes included decreased flow velocity as well as an increase in pulse pressure. Late changes consisted of a persistent increase of pulse pressure with the appearance of retrograde flow velocities during diastole. In the end stage, complete diastolic retrograde flow velocities were found. These gave rise to the characteristic reverberating pattern mentioned earlier. Identification of flow velocity reversal alone, however, proved to be inadequate for making the diagnosis of brain death. Evaluation of net flow velocity (calculated at bedside) was found to be a more sensitive determinant of brain death and closely paralleled the patients' neurological function.
经颅多普勒（TCD）超声检查用于对24例颅脑损伤患者进行多次检查，其中23例最终死亡。在这23例患者中的20例中，可获得足够的TCD信号，观察到一种特征性的振荡波形模式，所有病例的相关净流速均小于10厘米/秒。在我们研究组的最后一名患者中，也发现了振荡模式，然而，大于20厘米/秒的净流速与功能恢复相关。神经功能、TCD描记图和净流速之间的相关性有助于识别脑循环停止之前的特征性血流动力学变化。早期变化包括流速降低以及脉压增加。晚期变化包括脉压持续增加，舒张期出现逆流速度。在终末期，发现完全的舒张期逆流速度。这些导致了前面提到的特征性振荡模式。然而，仅流速逆转的识别被证明不足以诊断脑死亡。发现床边计算的净流速评估是脑死亡更敏感的决定因素，并且与患者的神经功能密切平行。
