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Journal of Biomedical Optics • Open Access

Optical oximetry of volume-oscillating vascular compartments: contributions from oscillatory blood flow

Paper Abstract

We present a quantitative analysis of dynamic diffuse optical measurements to obtain oxygen saturation of hemoglobin in volume oscillating compartments. We used a phasor representation of oscillatory hemodynamics at the heart rate and respiration frequency to separate the oscillations of tissue concentrations of oxyhemoglobin (O) and deoxyhemoglobin (D) into components due to blood volume (subscript V) and blood flow (subscript F): O=OV+OF, D=DV+DF. This is achieved by setting the phase angle Arg(OF)−Arg(O), which can be estimated by a hemodynamic model that we recently developed. We found this angle to be −72  deg for the cardiac pulsation at 1 Hz, and −7  deg for paced breathing at 0.1 Hz. Setting this angle, we can obtain the oxygen saturation of hemoglobin of the volume-oscillating vascular compartment, SV=|OV|/(|OV|+|DV|). We demonstrate this approach with cerebral near-infrared spectroscopy measurements on healthy volunteers at rest (n=4) and during 0.1 Hz paced breathing (n=3) with a 24-channel system. Rest data at the cardiac frequency were used to calculate the arterial saturation, S(a); over all subjects and channels, we found 〈SV〉=S(a)〉=0.96±0.02. In the case of paced breathing, we found 〈SV〉=0.66±0.14, which reflects venous-dominated hemodynamics at the respiratory frequency.

Paper Details

Date Published: 1 March 2016
PDF: 13 pages
J. Biomed. Opt. 21(10) 101408 doi: 10.1117/1.JBO.21.10.101408
Published in: Journal of Biomedical Optics Volume 21, Issue 10
Show Author Affiliations
Jana Marie Kainerstorfer, Tufts Univ. (United States)
Angelo Sassaroli, Tufts Univ. (United States)
Sergio Fantini, Tufts Univ. (United States)

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