Simultaneous measurements of total hemoglobin concentration and blood oxygenation with laser diode-based optoacoustic system

Noninvasive, accurate, continuous monitoring of multiple variables, including blood oxygenation, i.e. oxyhemoglobin saturation (SO₂) and total hemoglobin concentration (THb) in both high acuity and low acuity environments would greatly facilitate prompt diagnosis and treatment of physiologic derangements. However, most of the existing techniques for patient monitoring are invasive, while noninvasive techniques often fail to provide accurate measurements. We built a compact, multi-wavelength, nanosecond, fiber-coupled laser diode-based optoacoustic system for noninvasive, accurate monitoring of blood SO₂ and THb in veins and arteries. We tested the system by probing the radial artery of healthy volunteers. Using blood samples obtained by venipuncture, we also measured a reference THb for each volunteer. Moreover, the optoacoustic data were compared with that obtained from a commercially available noninvasive monitor for measurements of these variables. The optoacoustic system provided rapid, simultaneous, and continuous measurement of THb and SO₂ with high precision. The obtained results are promising and we plan to further test the system in clinical studies and at conditions simulating circulatory shock.