Department of Cerebral Function, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.
Department of Neurological Intensive Care Unit, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.
Neurocrit Care. 2022 Feb;36(1):21-29. doi: 10.1007/s12028-021-01301-5. Epub 2021 Aug 17.
Cerebral autoregulation plays an important role in safeguarding adequate cerebral perfusion and reducing the risk of secondary brain injury, which is highly important for patients in the neurological intensive care unit (neuro-ICU). Although the consensus white paper suggests that a minimum of 5 min of data are needed for assessing dynamic cerebral autoregulation with transfer function analysis (TFA), it remains unknown if the length of these data is valid for patients in the neuro-ICU, of whom are notably different than the general populations. We aimed to investigate the effect of data length using transcranial Doppler ultrasound combined with invasive blood pressure measurement for the assessment of dynamic cerebral autoregulation in patients in the neuro-ICU.
Twenty patients with various clinical conditions (severe acute encephalitis, ischemic stroke, subarachnoid hemorrhage, brain injury, cerebrovascular intervention operation, cerebral hemorrhage, intracranial space-occupying lesion, and toxic encephalopathy) were recruited for this study. Continuous invasive blood pressure, with a pressure catheter placed at the radial artery, and bilateral continuous cerebral blood flow velocity with transcranial Doppler ultrasound were simultaneously recorded for a length of 10 min for each patient. TFA was applied to derive phase shift, gain, and coherence function at all frequency bands from the first 2, 3, 4, 5, 6, 7, 8, 9, and 10 min of the 10-min recordings in each patient on both hemispheres. The variability in the autoregulatory parameters in each hemisphere was investigated by repeated measures analysis of variance.
Forty-one recordings (82 hemispheres) were included in the study. According to the critical values of coherence provided by the Cerebral Autoregulation Research Network white paper, acceptable rates for the data were 100% with a length ≥ 7 min. The final analysis included 68 hemispheres. The effects of data length on trends in phase shift in the very low frequency (VLF) band (F = 6.321, P = 0.003), in the LF band (F = 4.290, P = 0.032), and in the HF band (F = 3.868, P = 0.039) were significant for 3-7 min, for 4-7 min, and for 5-8 min, respectively. Effects were also significant on the gain in the VLF band (F = 3.215, P = 0.045) for 2-8 min and on the coherence function in all frequency bands (VLF F = 90.247, P < 0.001, LF F = 55.770, P < 0.001, HF F = 33.833, P < 0.001) for 2-10 min.
Considering the acceptable rates for the data and the variation in the TFA variables (phase shift and gain), we recommend recording data for a minimum length of 7 min for TFA in patients in the neuro-ICU.
脑自动调节在保障充足的脑灌注和降低继发脑损伤风险方面起着重要作用，这对神经重症监护病房（neuro-ICU）的患者尤为重要。尽管共识白皮书建议使用传递函数分析（TFA）评估动态脑自动调节需要至少 5 分钟的数据，但对于神经重症监护病房的患者，这些数据的长度是否有效仍不清楚，因为这些患者与一般人群明显不同。我们旨在研究使用经颅多普勒超声结合有创血压测量评估神经重症监护病房患者的动态脑自动调节时数据长度的影响。
本研究纳入了 20 名患有各种临床疾病（严重急性脑炎、缺血性中风、蛛网膜下腔出血、脑损伤、脑血管介入手术、脑出血、颅内占位病变和中毒性脑病）的患者。连续有创血压，通过桡动脉置管测量，以及双侧连续脑血流速度通过经颅多普勒超声同步记录，每位患者记录 10 分钟。在每个患者的每个半球上，将 TFA 应用于从 10 分钟记录的前 2、3、4、5、6、7、8、9 和 10 分钟中获得所有频率带的相位滞后、增益和相干函数。通过重复测量方差分析研究每个半球的自动调节参数的变异性。
本研究共纳入 41 份记录（82 个半球）。根据 Cerebral Autoregulation Research Network 白皮书提供的相干性临界值，数据长度≥7 分钟的可接受率为 100%。最终分析包括 68 个半球。数据长度对 3-7 分钟低频（VLF）带、4-7 分钟低频（LF）带和 5-8 分钟高频（HF）带的相位滞后趋势（F=6.321，P=0.003）、3-7 分钟 LF 带的增益（F=4.290，P=0.032）和 5-8 分钟 HF 带的增益（F=3.868，P=0.039）有显著影响。在 2-8 分钟的 VLF 带增益（F=3.215，P=0.045）和在所有频率带的相干函数（VLF F=90.247，P<0.001、LF F=55.770，P<0.001、HF F=33.833，P<0.001）方面也有显著影响。
考虑到数据的可接受率和 TFA 变量（相位滞后和增益）的变化，我们建议在神经重症监护病房的患者中，TFA 记录数据的最小长度至少为 7 分钟。
