Diffuse reflectance-based spectroscopic technique for real-time estimation of localized blood oxygenation parameters from human fingertips: A preliminary study

Non-invasive and real-time measurement of localized blood oxygenation parameters such as reduced hemoglobin, oxyhemoglobin, and oxygen saturation is regularly required by emergency & rescue teams as well as by intensive care units (ICUs). These parameters vary with gender and age. Therefore, the aim of this study is to investigate the ability of diffuse reflectance spectroscopy (DRS) to measure localized blood oxygenation parameters from the fingertips of human subjects and their variation with gender and age. 91 healthy subjects (male = 55 and female = 36) aged between 22 to 51 years were selected. The subjects were categorized into 5 age groups (20-24 years, 25-29 years, 30-34 years, 35-39 years, and above 40 years). DRS experiments were performed on the fingertips of each subject to record three sets of 150 diffuse reflectance spectra. The localized blood oxygenation parameters were derived from the recorded spectra. To compare gender and age-based variations in the relative change in reduced hemoglobin (ΔRHb), oxyhemoglobin (ΔHbO₂), and oxygen saturation (ΔSO₂), the Mann-Whitney U test and Kruskal- Wallis ANOVA test were performed, respectively. We found in the gender difference study that the female subjects have a significantly higher ΔRHb and ΔSO₂, but lower ΔHbO₂ than the male subjects (p < 0.001). The age variation study concludes that with the increase in age, ΔRHb is found to significantly increase, while ΔHbO₂ and ΔSO₂ are found to significantly decrease (p < 0.05). Thus, the preliminary investigation suggests that DRS has potential for real-time estimation of localized blood oxygenation parameters from the fingertips of human subjects which may be used to improve medical diagnosis and therapeutic assessment in ICU patients.