Optical investigation of variability in body region dependent transcutaneous oxygen saturation

Abstract

This paper presents the use of multispectral imaging system to investigate variability in transcutaneous oxygen saturation (StO2) amongst different individuals and at different skin sites. Noncontact reflectance data are collected from central forehead, posterior forearm, thenar region of palm and proximal ankle of three healthy Asians. The prediction of the required StO2 value is via fitting Extended Modified Lambert (EMLB) model to the measured attenuation data using extinction coefficient of hemoglobin components in the wavelength range of 520 - 600 nm as its priori knowledge. The obtained results revealed a relatively high mean StO2 of 54 ± 1.9% at the palm of the hand site. This is followed by measurement at foot ankle and forehead with StO2 of 52.3 ± 2.4% and 51.2 ± 7.7%, respectively. Meanwhile the lowest reading of StO2 of 48.8 ± 5.1% is observed at the posterior forearm. Based on these findings, this work concluded that palm of the hand would provide considerably consistent measurement of StO2 among individuals. This is largely owing to the higher density of circulatory anastomosis at this skin site. This implied viability of using the developed strategy in the studies of microcirculation mechanism especially on wound at this skin region.

Investigation of spatial resolution dependent variability in transcutaneous oxygen saturation using point spectroscopy system

“…The results in Table 1 and Figure 3 also revealed small standard deviation among these subjects, indicating good repeatability of the analytical technique and the proposed experimental method when the imaged skin site is of close proximity to the detection system (<50 mm). It must also be mentioned that a decrease in the StO2 value to 60.8 2.8%  at the 200 mm separation between skin site -detection system was of similar range to that observed in the previous related work in [17] that used multispectral imaging system. Based on the small differences in the predicted mean StO2 for the considered distance of 30 mm and 50 mm shown in Table 1, it is reasonable to assume that at a distance of less than 30 mm, no significant differences in StO2 would be observed.…”

“…In addition to the reduce signal to noise performance, this observed variation was probably due to differences in one's skin thickness, skin tone and health status. These observations were also reported in [17] whose work focused on central forehead, posterior forearm, thenar region of palm and proximal ankle of the recruited subjects. Although the present system may be used on other skin sites, index finger was selected here largely due to the fact that a higher StO2 is likely expected in acral skin (non-hairy skin sites i.e.…”

A Handheld Technology for Optical Monitoring of Transcutaneous Blood Oxygen Saturation

“…Since the employed light of wavelengths 532 nm, 560 nm, and 655 nm probed at a depth of no more than 550 µm below skin surface [7], its light path encompassed networks of capillaries, arteries and veins, and the measured S t O 2 was taken as the averaged of oxygen saturation of these blood vessels. Therefore the predicted S t O 2 in the range of 60 -80 % is agreeable with the results in [1] and [5], which works revealed the variation in this value depending on the selected skin site. This is in contrary to the arterial blood oxygen saturation value of 98 -100% measured using pulse oximeter from fingertip of a healthy individual.…”

Tissue Oxygen Level in Acute and Chronic Wound: A Comparison Study

“…Thus, these wounds were placed according to the convenient of the subjects and optimal focal position during the experiment. On this note, since measurements were performed on different body parts, in which the variation in mean StO2 was considerably large [29], the results are affected by several factors such as location of blood vessels in the measured region and light penetration depth depending on the melanocytes distribution. However under theoretical circumstances, detected reflected signals are assumed to have propagated in the skin medium and carry sufficient and useful information on scattering and absorption features of the investigation site.…”