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[Editor's Pick] Current Optics and Photonics Vol. 6 no. 5 (2022 October)

사무국 hit 671 date 2022-10-25

Cerebral Oxygenation Monitoring during a Variation of Isoflurane Concentration in a Minimally Invasive Rat Model

Dong-Hyuk Choi1, Sungchul Kim1, Teo Jeon Shin2, Seonghyun Kim1, and Jae Gwan Kim1 *

 

Current Optics and Photonics  Vol. 6 No. 5 (2022 October) pp. 489-496
DOI: https://doi.org/10.3807/COPP.2022.6.5.489

 

  Fig. 1  Schematic comparison of invasive and minimally invasive models.

 

 

Keywords: Cerebral blood volume, Depth of anesthesia, Isoflurane, Monte Carlo simulation, Near-infrared spectroscopy
OCIS codes: (170.1610) Clinical application; (170.2655) Functional monitoring and imaging; (170.4580) Optical diagnostics for medicine; (170.6510) Spectroscopy, tissue diag nostics


Abstract
Our previous study on monitoring cerebral oxygenation with a variation of isoflurane concentration in a rat model showed that near-infrared spectroscopy (NIRS) signals have potential as a new depth of anesthesia (DOA) index. However, that study obtained results from the brain in a completely invasive way, which is inappropriate for clinical application. Therefore, in this follow-up study, it was investigated whether the NIRS signals measured in a minimally invasive model including the skull and cerebrospinal fluid layer (CSFL) are similar to the previous study used as a gold standard. The experimental method was the same as the previous study, and only the subject model was different. We continuously collected NIRS signals before, during, and after isoflurane anesthesia. The isoflurane concentration started at 2.5% (v/v) and decreased to 1.0% by 0.5% every 5 min. The results showed a positive linear correlation between isoflurane concentration and ratio of reflectance intensity (RRI) increase, which is based on NIRS signals. This indicates that the quality of NIRS signals passed through the skull and CSFL in the minimally invasive model is as good as the signal obtained directly from the brain. Therefore, we believe that the results of this study can be easily applied to clinics as a potential indicator to monitor DOA.