Study And Application Of Absolute Detection Methods On Tissue Oxygenation By Using Near Infrared Spectroscopy

Based on the model of multi-layered biological tissue, a method to measure regional tissue oxygenation saturation by using noninvasive near infrared spectroscopy was given. For the subjects with different constructions and scales of their overlaying tissue, the influence of overlaying tissue on the value of blood oxygen parameters, which were measured for subjects was investigated by using Monte Carlo simulating method. It shows that as the distance between source and detector was more than 20mm and the thickness of overlying tissue was less than 10mm, the value of regional tissue oxygenation saturation were not distorted. The value of concentration of Hb and HbO2 must be corrected if the thickness of overlying tissue was in the 5mm to 10mm range. Correction method which make results reliable and comparable in measuring tissue blood oxygenation was proposed. A steady-state spatially resolved NIRS oximeter was developed for the monitoring regional tissue oxygenation. Suitable probes were designed for different clinical applications so that they can be fixed on the tissue surface reliably in a long-time monitoring. The oximeter can fulfill the clinical requirements on safety and stability. The instrument was also calibrated by tissue phantom and ischaemia of forearm experiment.Using the steady-state spatially resolved NIRS oximeter for monitoring cerebral oxygenation of healthy neonates and neonates with hypoxic-ischemic encephalopathy (HIE) were studied by experimental method. Characteristic parameters in different oxygen state were analyzed, which would be helpful for the clinical to discover and assess of cerebral oxygen in neonates. Using the steady-state spatially resolved NIRS oximeter for measuring skeletal muscle oxygen metabolism of healthy volunteers and athletes was investigated by experimental method. The result shows that the changes of blood volume and tissue oxygenation saturation in athletes were different from the control, the capacity of muscle oxygen metabolism in athletes is better than the control. In summary, the results of this study provide a potential method to realize the noninvasive quantitative evaluation of oxidative metabolism on muscles by near-infrared spectroscopy technology. This method can be applied to assess training effect of athletes and select candidate of athletes.