| Summary: | Tissue oxygen monitoring systems, such as pulse oximeter, is
unreliable in patients with compromised microcirculation. Modern
imaging modalities such as Magnetic Resonance Imaging (MRI)
offer good diagnostic accuracy at the expense of increased cost
and complexity in their operations. This paper studies the use of
photoacoustic (PA) phase change as a predictor of skin tissue
oxygen levels. We used EPOCH 650 ultrasonic flaw detector with a
longitudinal transducer for measurement of PA waves. This pilot
study was conducted on six human subjects. The produced
ultrasonic waves were collected from their anterior left arm under
three experimental conditions, namely at rest, venous and arterial
blood flow occlusions, for determination of hemoglobin absorption
dependent phase change in tissue. The overall mean and standard
deviation (STDEV) of phase angles for at rest condition are
calculated as 1.43 ± 0.06 radians (rads). Higher phase angles are
determined for diastolic and systolic occlusion pressures given by
1.69 ± 0.05 rads and 2.09 ± 0.06 rads, respectively. This work
concluded that the feasibility of our PA system to monitor changes
in tissue oxygen performance renders it a promising alternative for
portable assessment and measurement of oxygen concentration
within microcirculation environment.
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