title: Design of a visible-light spectroscopy clinical tissue oximeter.
abstract: We develop a clinical visible-light spectroscopy (VLS) tissue oximeter. Unlike currently approved near-infrared spectroscopy (NIRS) or pulse oximetry (SpO2%), VLS relies on locally absorbed, shallow-penetrating visible light (475 to 625 nm) for the monitoring of microvascular hemoglobin oxygen saturation (StO2%), allowing incorporation into therapeutic catheters and probes. A range of probes is developed, including noncontact wands, invasive catheters, and penetrating needles with injection ports. Data are collected from: 1. probes, standards, and reference solutions to optimize each component; 2. ex vivo hemoglobin solutions analyzed for StO2% and pO2 during deoxygenation; and 3. human subject skin and mucosal tissue surfaces. Results show that differential VLS allows extraction of features and minimization of scattering effects, in vitro VLS oximetry reproduces the expected sigmoid hemoglobin binding curve, and in vivo VLS spectroscopy of human tissue allows for real-time monitoring (e.g., gastrointestinal mucosal saturation 69+/-4%, n=804; gastrointestinal tumor saturation 45+/-23%, n=14; and p<0.0001), with reproducible values and small standard deviations (SDs) in normal tissues. FDA approved VLS systems began shipping earlier this year. We conclude that VLS is suitable for the real-time collection of spectroscopic and oximetric data from human tissues, and that a VLS oximeter has application to the monitoring of localized subsurface hemoglobin oxygen saturation in the microvascular tissue spaces of human subjects.
authors.affiliation: Stanford University School of Medicine, Department of Pediatrics, Division of Neonatal and Developmental Medicine, Palo Alto, California 94305, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Benaron
authors.forename: Ilian H
authors.initials: IH
authors.lastname: Parachikov
authors.forename: Wai-Fung
authors.initials: WF
authors.lastname: Cheong
authors.forename: Shai
authors.initials: S
authors.lastname: Friedland
authors.forename: Boris E
authors.initials: BE
authors.lastname: Rubinsky
authors.forename: David M
authors.initials: DM
authors.lastname: Otten
authors.forename: Frank W H
authors.initials: FW
authors.lastname: Liu
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Levinson
authors.forename: Aileen L
authors.initials: AL
authors.lastname: Murphy
authors.forename: John W
authors.initials: JW
authors.lastname: Price
authors.forename: Yair
authors.initials: Y
authors.lastname: Talmi
authors.forename: James P
authors.initials: JP
authors.lastname: Weersing
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Duckworth
authors.forename: Uwe B
authors.initials: UB
authors.lastname: Hörchner
authors.forename: Eben L
authors.initials: EL
authors.lastname: Kermit
mesh_terms: D000465:Algorithms; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D019723:Endoscopes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D008027:Light; D010092:Oximetry / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods
chemical_list: D006454:Hemoglobins