From the Medtronic Respiratory & Monitoring Solutions, Edinburgh, United Kingdom.
Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.
Anesth Analg. 2020 Nov;131(5):1520-1528. doi: 10.1213/ANE.0000000000004614.
Cerebral blood flow (CBF) is maintained over a range of blood pressures through cerebral autoregulation (CA). Blood pressure outside the range of CA, or impaired autoregulation, is associated with adverse patient outcomes. Regional oxygen saturation (rSO2) derived from near-infrared spectroscopy (NIRS) can be used as a surrogate CBF for determining CA, but existing methods require a long period of time to calculate CA metrics. We have developed a novel method to determine CA using cotrending of mean arterial pressure (MAP) with rSO2that aims to provide an indication of CA state within 1 minute. We sought to determine the performance of the cotrending method by comparing its CA metrics to data derived from transcranial Doppler (TCD) methods.
Retrospective data collected from 69 patients undergoing cardiac surgery with cardiopulmonary bypass were used to develop a reference lower limit of CA. TCD-MAP data were plotted to determine the reference lower limit of CA. The investigated method to evaluate CA state is based on the assessment of the instantaneous cotrending relationship between MAP and rSO2 signals. The lower limit of autoregulation (LLA) from the cotrending method was compared to the manual reference derived from TCD. Reliability of the cotrending method was assessed as uptime (defined as the percentage of time that the state of autoregulation could be measured) and time to first post.
The proposed method demonstrated minimal mean bias (0.22 mmHg) when compared to the TCD reference. The corresponding limits of agreement were found to be 10.79 mmHg (95% confidence interval [CI], 10.09-11.49) and -10.35 mmHg (95% CI, -9.65 to -11.05). Mean uptime was 99.40% (95% CI, 99.34-99.46) and the mean time to first post was 63 seconds (95% CI, 58-71).
The reported cotrending method rapidly provides metrics associated with CA state for patients undergoing cardiac surgery. A major strength of the proposed method is its near real-time feedback on patient CA state, thus allowing for prompt corrective action to be taken by the clinician.
通过脑自动调节（CA），脑血流量（CBF）可在血压范围内维持稳定。血压超出 CA 范围或调节受损与患者不良预后相关。近红外光谱（NIRS）衍生的局部氧饱和度（rSO2）可作为 CA 的替代 CBF 用于确定 CA，但现有的方法需要很长时间来计算 CA 指标。我们开发了一种新的方法，通过 rSO2 与平均动脉压（MAP）的共趋势来确定 CA，旨在在 1 分钟内提供 CA 状态的指示。我们通过将共趋势方法的 CA 指标与经颅多普勒（TCD）方法得出的数据进行比较，来确定共趋势方法的性能。
使用从 69 例行体外循环心脏手术的患者中收集的回顾性数据，确定 CA 的参考下限。绘制 TCD-MAP 数据以确定 CA 的参考下限。评估 CA 状态的研究方法是基于评估 MAP 和 rSO2 信号之间瞬时共趋势关系。共趋势方法的自动调节下限（LLA）与 TCD 手动参考值进行比较。通过在线时间（定义为可测量自动调节状态的时间百分比）和首次后测量时间来评估共趋势方法的可靠性。
与 TCD 参考相比，所提出的方法显示出最小的平均偏差（0.22 mmHg）。发现相应的一致性界限为 10.79 mmHg（95%置信区间[CI]，10.09-11.49）和-10.35 mmHg（95% CI，-9.65 至-11.05）。平均在线时间为 99.40%（95% CI，99.34-99.46），首次后测量时间的平均值为 63 秒（95% CI，58-71）。
报告的共趋势方法快速为接受心脏手术的患者提供与 CA 状态相关的指标。该方法的一个主要优势是它可以实时反馈患者的 CA 状态，从而允许临床医生及时采取纠正措施。
