Abad Gurumeta A, Calvo Vecino J M, Abad Motos A, Olidén Gutiérrez L, García Alvarez R, Nieto Moreno A
Servicio de Anestesiología y Reanimación del Hospital Infanta Sofía, Madrid.
Rev Esp Anestesiol Reanim. 2010 Dec;57(10):630-8. doi: 10.1016/s0034-9356(10)70299-1.
Transcranial Doppler ultrasound is a noninvasive technique for monitoring the velocity of blood flow in the main intracranial arteries, particularly those in the circle of Willis. Our aim was to assess whether changes in cerebral arterial blood flow in pediatric patients under sevoflurane anesthesia demonstrated by pulsed Doppler ultrasound correlate with changes in the bispectral (BIS) index and electroencephalographic state and response entropy (ES and ER, respectively).
Prospective, blinded observational study of 36 pediatric patients (age range, 5 to 11 years; ASA physical status classification, 1-2) under sevoflurane anesthesia for minor surgical procedures. Anesthesia was induced with sevoflurane and maintained with 2.5% sevoflurane in an inspired oxygen fraction of 50% in air. A continuous perfusion of remifentanil was provided for analgesia. In all patients we monitored hemodynamic and respiratory patterns, gases, temperature, and hypnosis (BIS, ES and ER) as well as cerebral blood flow estimated by pulsed Doppler ultrasound in the middle cerebral artery. The resistance index, pulsatility index, mean velocity, and estimated baseline cerebral blood flow were calculated from the Doppler sonogram. Correlations (Pearson's r) were calculated between BIS, ES, ER, the pulsatility index, resistance index, mean flow velocity, estimated cerebral blood flow, fraction of end-tidal carbon dioxide, and temperature. A regression model was constructed.
Induction caused a pattern of high velocity (elevated mean velocity and normal or reduced pulsatility index) until the lowest BIS and ES values of 31 and 29, respectively, were reached. During maintenance, the Doppler sonogram pattern was slower (normalization of the pulsatility index, the resistance index, and mean velocity). Changes in flow and absolute entropy and BIS values were statistically correlated (Pearson's r values > or = 0.91); there was 95.6% agreement between Doppler values and BIS and agreement between BIS and ES values of 35 to 45. On awakening, flow velocities approached baseline values when BIS and ES rose to between 90 and 98. The estimated cerebral blood flow underwent fluctuations coinciding with an approximately concomitant increase or decrease in BIS (r > 0.95); the BIS response occurred with a slight delay of no more than a minute. The entropy measurements did not reflect the fluctuations.
We show Doppler ultrasound patterns during anesthetic induction with sevoflurane. Systems for monitoring hypnosis could be considered indirect measurements of cerebral blood flow; BIS measurements are more sensitive to change. Transcranial Doppler ultrasound facilitates the observation of changes in blood flow that occur at different levels of hypnosis during anesthesia.
经颅多普勒超声是一种用于监测颅内主要动脉，尤其是 Willis 环中动脉血流速度的无创技术。我们的目的是评估脉冲多普勒超声所显示的七氟醚麻醉下儿科患者脑动脉血流变化是否与脑电双频指数（BIS）及脑电图状态和反应熵（分别为 ES 和 ER）的变化相关。
对 36 例接受小手术的儿科患者（年龄范围 5 至 11 岁；ASA 身体状况分级为 1 - 2 级）进行前瞻性、盲法观察研究。用七氟醚诱导麻醉，然后在吸入氧分数为 50%的空气中用 2.5%七氟醚维持麻醉。持续输注瑞芬太尼用于镇痛。在所有患者中，我们监测血流动力学和呼吸模式、气体、体温以及催眠状态（BIS、ES 和 ER），同时通过脉冲多普勒超声估计大脑中动脉的脑血流量。根据多普勒超声图计算阻力指数、搏动指数、平均速度以及估计的基线脑血流量。计算 BIS、ES、ER、搏动指数、阻力指数、平均血流速度、估计脑血流量、呼气末二氧化碳分数和体温之间的相关性（Pearson 相关系数 r）。构建回归模型。
诱导期出现高速血流模式（平均速度升高，搏动指数正常或降低），直至分别达到最低 BIS 值 31 和最低 ES 值 29。维持期，多普勒超声图模式血流速度减慢（搏动指数、阻力指数和平均速度恢复正常）。血流变化与绝对熵及 BIS 值在统计学上具有相关性（Pearson 相关系数 r 值≥0.91）；多普勒值与 BIS 之间的一致性为 95.6%，BIS 与 ES 值在（35 至 45）之间具有一致性。苏醒时，当 BIS 和 ES 升至 90 至 98 之间时，血流速度接近基线值。估计的脑血流量波动与 BIS 的大致同步升高或降低相一致（r > 0.95）；BIS 反应出现稍有延迟，不超过 1 分钟。熵测量未反映出这些波动。
我们展示了七氟醚麻醉诱导期的多普勒超声模式。监测催眠状态的系统可被视为脑血流量的间接测量方法；BIS 测量对变化更敏感。经颅多普勒超声有助于观察麻醉期间不同催眠水平下发生的血流变化。
