Nissen Peter, van Lieshout Johannes J, Nielsen Henning B, Secher Niels H
Department of Anesthesia, Rigshospitalet, University of Copenhagen, Denmark.
AANA J. 2009 Aug;77(4):271-6.
Near-infrared spectroscopy (NIRS) assesses cerebral oxygen saturation (Sco2) as a balance between cerebral oxygen delivery and consumption. In 71 patients, we evaluated whether marked reduction in mean arterial pressure (MAP) during propofol-fentanyl anesthesia induction affects frontal lobe Sco2. The NIRS-determined arm muscle oxygenation (Smo2), heart rate (HR), and cardiac output (CO) were monitored, endtidal carbon dioxide tension was controlled at 3.5 to 4.5 kPa, and central blood volume was maintained. Before anesthesia, the median (range) MAP, HR, and CO were 93 mm Hg (61-126 mm Hg), 76 beats/min (50-96 beats/min), and 5.3 L/min (2.4-9.0 L/min), respectively, but immediately following intravenous administration of fentanyl and propofol, MAP decreased to 63 mm Hg (37-109 mm Hg), HR to 63 beats/min (40-103 beats/min), and CO to 4.1 L/min (7.9-70 L/min) (P < .05). When blood pressure decreased, the median (range) NIRS-determined Smo2 also decreased (73% [54%-94%] to 71% [52%-87%]), whereas Sco2 increased from 67% (46%-93%) to 74% (48%-95%) (P < .05), independent of age and gender. After anesthesia induction, variables recovered and remained at preanesthetic levels during surgery. The findings implicate that even an approximately 30% drop in MAP at the induction of anesthesia does not typically affect cerebral oxygenation.
近红外光谱法（NIRS）通过评估脑氧输送与消耗之间的平衡来测定脑氧饱和度（Sco2）。在71例患者中，我们评估了丙泊酚-芬太尼麻醉诱导期间平均动脉压（MAP）的显著降低是否会影响额叶Sco2。监测NIRS测定的手臂肌肉氧合（Smo2）、心率（HR）和心输出量（CO），将呼气末二氧化碳分压控制在3.5至4.5kPa，并维持中心血容量。麻醉前，MAP、HR和CO的中位数（范围）分别为93mmHg（61-126mmHg）、76次/分钟（50-96次/分钟）和5.3L/分钟（2.4-9.0L/分钟），但在静脉注射芬太尼和丙泊酚后，MAP立即降至63mmHg（37-109mmHg），HR降至63次/分钟（40-103次/分钟），CO降至4.1L/分钟（7.9-70L/分钟）（P<.05）。血压下降时，NIRS测定Smo2的中位数（范围）也下降（从73%[54%-94%]降至71%[52%-87%]），而Sco2从67%（46%-93%）升至74%（48%-95%）（P<.05），与年龄和性别无关。麻醉诱导后，各项变量恢复并在手术期间维持在麻醉前水平。研究结果表明，即使在麻醉诱导时MAP下降约30%，通常也不会影响脑氧合。
