Optoacoustic technique for continuous, noninvasive measurement of total hemoglobin concentration: an in vivo study

We used an optoacoustic technique to measure continuously and noninvasively total hemoglobin concentration in human blood in vivo. An optoacoustic probe, which combined illuminating fibers and a piezoelectric sensitive element, was placed in contact with the skin over the radial artery. Measurements in healthy volunteers agreed well with actual hemoglobin concentration.

In vivo noninvasive monitoring of cerebral blood with optoacoustic technique

We present the results of blood oxygenation (oxyhemoglobin saturation) measurements using an optoacoustic system in vivo in the superior sagittal sinus of sheep. The system included a nanosecond Nd:YAG laser as a source of radiation and a specially designed optoacoustic probe for signal detection. The optoacoustic signal induced in the superior sagittal sinus by the nanosecond laser pulses correlated well with actual oxyhemoglobin saturation measured with CO-oximeter. We propose to use a two- or multi- wavelength optoacoustic system for noninvasive continuous monitoring of cerebral venous blood oxygenation. The spectra of effective attenuation coefficient were measured in the range 680-1300 nm for oxy- and deoxygenated whole blood and can be employed for calibration of the system.

Dose-dependent disposition of n-hexane in F-344 rats after inhalation exposure

The purpose of this study was to assess the disposition of radioactivity in rats after single inhalation exposures to varying concentrations of [1,2-14C]-n-hexane. Male Fischer 344 rats were exposed to 500, 1000, 3000 or 10,000 ppm 14C-n-hexane for 6 hr and the elimination of radioactivity followed for 72 hr after exposure. The disposition of radioactivity was dose-dependent, with 12, 24, 38 and 62% of the acquired body burden excreted as n-hexane by the lung with increasing exposure concentration. In contrast, 38, 31, 27 and 18% of the body burden of radioactivity was recovered as expired 14CO2 and 35, 40, 31 and 18% was recovered in the urine with increasing n-hexane concentration. Radioactivity remaining in the tissues and carcass 72 hr after exposure represented 6.1, 8.8, 7.4 and 5.4% of the body burden for the respective exposures. The dose-dependent elimination of radioactivity was apparently due in part to an inhibition of n-hexane metabolism, reflected by a decrease in total 14CO2 and urinary 14C excretion after 10,000 ppm exposure compared to the 3000 ppm exposure.