Measurement using the currently available tissue oxygen monitoring systems, such as pulse oximeter, is unreliable in patients with compromised microcirculation. Others offer high diagnostic accuracy, but are complicated and expensive in their operation. This paper is motivated to study the use of photoacoustic (PA) phase change as a predictor of skin tissue oxygen levels. This work used EPOCH 650 ultrasonic flaw detector with a longitudinal transducer and a red laser light of wavelength 633 nm for measurement of PA signals. This pilot study was conducted on a group of four human subjects. The pressure waves were collected from their anterior left arm under three experimental conditions, namely at rest, venous and arterial blood flow occlusions, for extraction of hemoglobin absorption dependent phase information.