Design of a visible-light spectroscopy clinical tissue oximeter.
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.
Benaron
David A
DA
Stanford University School of Medicine, Department of Pediatrics, Division of Neonatal and Developmental Medicine, Palo Alto, California 94305, USA.
Parachikov
Ilian H
IH
Cheong
Wai-Fung
WF
Friedland
Shai
S
Rubinsky
Boris E
BE
Otten
David M
DM
Liu
Frank W H
FW
Levinson
Carl J
CJ
Murphy
Aileen L
AL
Price
John W
JW
Talmi
Yair
Y
Weersing
James P
JP
Duckworth
Joshua L
JL
Hörchner
Uwe B
UB
Kermit
Eben L
EL
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
D006454:Hemoglobins