Soehle Martin, Ellerkmann Richard K, Grube Matthias, Kuech Matthias, Wirz Stefan, Hoeft Andreas, Bruhn Joergen
Department of Anesthesiology and Intensive Care Medicine, University of Bonn, Bonn, Germany.
Anesthesiology. 2008 Nov;109(5):799-805. doi: 10.1097/ALN.0b013e3181895fd0.
The Bispectral Index (BIS) and the Patient State Index (PSI) quantify depth of anesthesia by analyzing the electroencephalogram. The authors examined the response of BIS and PSI to sevoflurane anesthesia.
In 22 patients, sevoflurane anesthesia was induced by inhalation with a tight-fitting facemask and was maintained via a laryngeal mask. Sevoflurane concentrations were increased until burst suppression occurred and subsequently decreased until BIS recovered to values above 60. This procedure was repeated twice until patients underwent intubation for subsequent surgery. End-tidal sevoflurane concentrations, BIS, and PSI were recorded simultaneously. The performance of PSI and BIS to predict the estimated sevoflurane effect site concentration, as derived from simultaneous pharmacokinetic and pharmacodynamic modeling, was compared by determination coefficients (rho(2)) and prediction probabilities (P(K)).
A significant (P < 0.001) correlation between BIS and PSI was found (r(2) = 0.75), and a close sigmoid relation between sevoflurane effect site concentration and both BIS (rho(2) = 0.84 +/- 0.09) and PSI (rho(2) = 0.85 +/- 0.15) was observed. The maximum sevoflurane electroencephalographic effect resulted in PSI values (1.3 +/- 4.3) that were significantly (P = 0.019) lower than BIS values (7.9 +/- 12.1), and the effect site efflux constant k(e0) was significantly smaller (P = 0.001) for PSI (0.13 +/- 0.08 min(-1)) than for BIS (0.24 +/- 0.15 min(-1)). The probability of BIS (P(K) = 0.80 +/- 0.11) to predict sevoflurane effect site concentration did not differ (P = 0.76) from that of PSI (P(K) = 0.79 +/- 0.09).
The BIS reacted faster to changes in sevoflurane concentrations, whereas the PSI made better use of the predefined index range. However, despite major differences in their algorithms and minor differences in their dose-response relations, both PSI and BIS predicted depth of sevoflurane anesthesia equally well.
脑电双频指数（BIS）和患者状态指数（PSI）通过分析脑电图来量化麻醉深度。作者研究了BIS和PSI对七氟烷麻醉的反应。
22例患者，通过紧密贴合的面罩吸入诱导七氟烷麻醉，并通过喉罩维持。增加七氟烷浓度直至出现爆发抑制，随后降低浓度直至BIS恢复到60以上的值。此过程重复两次，直到患者接受插管进行后续手术。同时记录呼气末七氟烷浓度、BIS和PSI。通过决定系数（rho(2)）和预测概率（P(K)）比较PSI和BIS预测从同时进行的药代动力学和药效学模型得出的估计七氟烷效应室浓度的性能。
发现BIS和PSI之间存在显著相关性（P < 0.001）（r(2) = 0.75），并且观察到七氟烷效应室浓度与BIS（rho(2) = 0.84 +/- 0.09）和PSI（rho(2) = 0.85 +/- 0.15）之间存在密切的S形关系。七氟烷最大脑电图效应导致PSI值（1.3 +/- 4.3）显著低于BIS值（7.9 +/- 12.1）（P = 0.019），并且PSI的效应室流出常数k(e0)（0.13 +/- 0.从0.08分钟(-1)）比BIS（0.24 +/- 0.15分钟(-1)）显著更小（P = 0.001）。BIS预测七氟烷效应室浓度的概率（P(K) = 0.80 +/- 0.11）与PSI（P(K) = 0.79 +/- 0.09）相比无差异（P = 0.76）。
BIS对七氟烷浓度变化的反应更快，而PSI能更好地利用预定义的指数范围。然而，尽管它们的算法存在重大差异且剂量反应关系存在微小差异，但PSI和BIS对七氟烷麻醉深度的预测效果同样良好。
