Greening Gage J, Miller Kathryn P, Spainhour Caroline R, Cato Mattison D, Muldoon Timothy J
Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR 72701, USA.
Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA.
Biomed Opt Express. 2018 May 31;9(6):2871-2886. doi: 10.1364/BOE.9.002871. eCollection 2018 Jun 1.
Diffuse reflectance spectroscopy (DRS) has been used in murine studies to quantify tumor perfusion and therapeutic response. These studies frequently use inhaled isoflurane anesthesia, which depresses the respiration rate and results in the desaturation of arterial oxygen saturation, potentially affecting tissue physiological parameters. However, there have been no controlled studies quantifying the effect of isoflurane anesthesia on DRS-derived physiological parameters of murine tissue. The goal of this study was to perform DRS on Balb/c mouse (n = 10) tissue under various anesthesia conditions to quantify effects on tissue physiological parameters, including total hemoglobin concentration, tissue oxygen saturation, oxyhemoglobin and reduced scattering coefficient. Two independent variables were manipulated including metabolic gas type (pure oxygen vs. medical air) and isoflurane concentration (1.5 to 4.0%). The 1.5% isoflurane and 1 L/min oxygen condition most closely mimicked a no-anesthesia condition with oxyhemoglobin concentration within 89% ± 19% of control. The time-dependent effects of isoflurane anesthesia were tested, revealing that anesthetic induction with 4.0% isoflurane can affect DRS-derived physiological parameters up to 20 minutes post-induction. Finally, spectroscopy with and without isoflurane anesthesia was compared for colon tumor Balb/c-CT26 allografts (n = 5) as a representative model of subcutaneous murine tumor allografts. Overall, isoflurane anesthesia yielded experimentally-induced depressed oxyhemoglobin, and this depression was both concentration and time dependent. Investigators should understand the dynamic effects of isoflurane on tissue physiological parameters measured by DRS. These results may guide investigators in eliminating, limiting, or managing anesthesia-induced physiological changes in DRS studies in mouse models.
漫反射光谱法（DRS）已用于小鼠研究，以量化肿瘤灌注和治疗反应。这些研究经常使用吸入异氟烷麻醉，这会降低呼吸频率并导致动脉血氧饱和度下降，可能会影响组织生理参数。然而，尚无对照研究量化异氟烷麻醉对小鼠组织DRS衍生生理参数的影响。本研究的目的是在各种麻醉条件下对Balb/c小鼠（n = 10）组织进行DRS，以量化对组织生理参数的影响，包括总血红蛋白浓度、组织氧饱和度、氧合血红蛋白和减少散射系数。操纵了两个独立变量，包括代谢气体类型（纯氧与医用空气）和异氟烷浓度（1.5%至4.0%）。1.5%异氟烷和1 L/min氧气条件最接近无麻醉条件，氧合血红蛋白浓度在对照的89%±19%范围内。测试了异氟烷麻醉的时间依赖性影响，结果表明，用4.0%异氟烷进行麻醉诱导可在诱导后长达20分钟内影响DRS衍生的生理参数。最后，比较了有无异氟烷麻醉的光谱法对结肠肿瘤Balb/c-CT26同种异体移植物（n = 5）的影响，作为皮下小鼠肿瘤同种异体移植物的代表性模型。总体而言，异氟烷麻醉导致实验诱导的氧合血红蛋白降低，这种降低与浓度和时间有关。研究人员应了解异氟烷对DRS测量的组织生理参数的动态影响。这些结果可能会指导研究人员在小鼠模型的DRS研究中消除、限制或管理麻醉诱导的生理变化。
