Yoshitani Kenji, Kawaguchi Masahiko, Miura Norikazu, Okuno Takashi, Kanoda Tomoko, Ohnishi Yoshihiko, Kuro Masakazu
Department of Anesthesiology, National Cardiovascular Center, Nara Medical University, Kashihara, Nara, Japan.
Anesthesiology. 2007 Mar;106(3):458-62. doi: 10.1097/00000542-200703000-00009.
Previous studies documented that near-infrared spectroscopy values were affected by factors related to optical path length, such as hemoglobin concentration, the differential path length factor, skull thickness (t-skull), and the area of the cerebrospinal fluid layer (a-CSFL). Lately, the NIRO-100 (Hamamatsu Photonics, Hamamatsu, Japan) has provided a tissue oxygen index (TOI) that theoretically is not supposed to be affected by optical path length. Therefore, the authors hypothesized that TOI is not influenced by the above-described individual factors.
Cardiac surgical or neurosurgical 103 patients (65 men and 39 women; aged 63 +/- 14 yr) were studied. TOI and regional cerebral oxygen saturation (rSO2) (INVOS 4100; Somanetics, Troy, MI) were measured sequentially on patients in a resting state. The t-skull and a-CSFL were calculated using computed tomographic image slices of the head corresponding with the position of near-infrared spectroscopy sensors. The effects of these two factors, hemoglobin concentration and mean arterial pressure, on TOI and rSO2 values were evaluated by linear regression analysis.
Simple linear regression analysis showed that mean arterial pressure (r = 0.27, P = 0.008), t-skull (r = 0.22, P = 0.034), a-CSFL (0.26, P = 0.012), and hemoglobin concentration (r = 0.42, P < 0.0001) were significant determinants of rSO2. Multiple linear regression analysis showed that hemoglobin concentration (r = 0.34, P < 0.001), a-CSFL (r = -0.252, P = 0.012), and t-skull (r = 0.22, P = 0.037) were significant determinants of rSO2. On the other hand, simple and multiple linear regression analysis showed that there was no significant determinant of TOI.
rSO2 values were affected by hemoglobin concentration, a-CSFL, and t-skull, but TOI values were not affected by individual factors.
以往研究表明，近红外光谱值受与光程长度相关的因素影响，如血红蛋白浓度、微分光程长度因子、颅骨厚度（t-颅骨）和脑脊液层面积（a-CSFL）。最近，NIRO-100（日本滨松光子学公司，滨松）提供了一种组织氧合指数（TOI），理论上该指数不应受光程长度影响。因此，作者推测TOI不受上述个体因素影响。
对103例心脏外科或神经外科患者（65例男性和39例女性；年龄63±14岁）进行研究。在静息状态下依次测量患者的TOI和局部脑氧饱和度（rSO2）（INVOS 4100；美国密歇根州特洛伊市Somanetics公司）。使用与近红外光谱传感器位置对应的头部计算机断层扫描图像切片计算t-颅骨和a-CSFL。通过线性回归分析评估这两个因素、血红蛋白浓度和平均动脉压对TOI和rSO2值的影响。
简单线性回归分析显示，平均动脉压（r = 0.27，P = 0.008）、t-颅骨（r = 0.22，P = 0.034）、a-CSFL（0.26，P = 0.012）和血红蛋白浓度（r = 0.42，P < 0.0001）是rSO2的显著决定因素。多元线性回归分析显示，血红蛋白浓度（r = 0.34，P < 0.001）、a-CSFL（r = -0.252，P = 0.012）和t-颅骨（r = 0.22，P = 0.037）是rSO2的显著决定因素。另一方面，简单和多元线性回归分析显示，没有显著因素决定TOI。
rSO2值受血红蛋白浓度、a-CSFL和t-颅骨影响，但TOI值不受个体因素影响。
