INTRODUCTION The optimal method to detect impairments in cerebrovascular pressure autoregulation in neonates with hypoxic-ischemic encephalopathy (HIE) is unclear. Improving autoregulation monitoring methods would significantly advance neonatal neurocritical care. METHODS We tested several mathematical algorithms from the frequency and time domains in a piglet model of HIE, hypothermia, and hypotension. We used laser Doppler flowmetry and induced hypotension to delineate the gold standard lower limit of autoregulation (LLA). Receiver operating characteristics curve analyses were used to determine which indices could distinguish blood pressure above the LLA from that below the LLA in each piglet. RESULTS Phase calculation in the frequency band with maximum coherence, as well as the correlation between mean arterial pressure (MAP) and near-infrared spectroscopy relative total tissue hemoglobin (HbT) or regional oxygen saturation (rSO2), accurately discriminated functional from dysfunctional autoregulation. Neither hypoxia-ischemia nor hypothermia affected the accuracy of these indices. Coherence alone and gain had low diagnostic value relative to phase and correlation. CONCLUSION Our findings indicate that phase shift is the most accurate component of autoregulation monitoring in the developing brain, and it can be measured using correlation or by calculating phase when coherence is maximal. Phase and correlation autoregulation indices from MAP and rSO2 and vasoreactivity indices from MAP and HbT are accurate metrics that are suitable for clinical HIE studies.

中文翻译：

---

低氧缺血和低温的仔猪模型中频域和时域自动调节与血管反应指数的比较。

引言目前尚不清楚检测缺氧缺血性脑病（HIE）新生儿脑血管压力自动调节障碍的最佳方法。改善自动调节监测方法将大大促进新生儿神经重症监护。方法我们在HIE，体温过低和低血压的仔猪模型中从频域和时域测试了几种数学算法。我们使用激光多普勒血流仪和诱发性低血压来描绘金标准的自动调节下限（LLA）。接收者的工作特性曲线分析被用来确定哪些指标可以区分每只仔猪的LLA以上和LLA以下的血压。结果在具有最大相干性的频带中进行相位计算，以及平均动脉压（MAP）和近红外光谱法相对总组织血红蛋白（HbT）或区域氧饱和度（rSO2）之间的相关性，可以将功能正常与功能正常的自动调节区分开。缺氧缺血和低温都不会影响这些指标的准确性。相对于相位和相关性，仅相干性和增益具有较低的诊断价值。结论我们的研究结果表明，相移是发育中的大脑自动调节监测的最准确组成部分，当相关性最大时，可以使用相关性或通过计算相位来测量相移。来自MAP和rSO2的相位和相关自动调节指数以及来自MAP和HbT的血管反应指数是适用于临床HIE研究的准确指标。