Comparative assessment of healthy tissue oxygenation using near-infrared imaging, transcutaneous oxygen measurement, and plethysmography

Abstract

The COVID-19 pandemic highlighted critical limitations in conventional pulse oximetry, especially in diverse populations. This study evaluates the performance of noninvasive devices for assessing tissue oxygenation in a cohort of 20 healthy individuals, with a focus on device sensitivity, physiological and demographic variables. Tissue oxygenation was measured using devices: spatial frequency domain imaging (SFDI), transcutaneous oxygen measurement (TCOM), wearable photoplethysmography (WD), and pulse oximetry (PO) during baseline, ischemia, and reperfusion phases. Comparative analyses were performed across devices, sex and Fitzpatrick skin types. Among the four devices, SFDI uniquely detected significant differences in tissue oxygen saturation (StO2), highlighting its sensitivity to tissue heterogeneity. PO and WD data showed moderate correlation (r = 0.44-0.59); SFDI and TCOM demonstrated fair correlation (r = 0.23-0.36). Although sex-based differences were minimal, the SFDI revealed significantly different recovery metrics. Notably, SFDI provided deeper insights into hemoglobin dynamics (HbO2, dHb, HbP1, HbP2), which was not captured by point-measurement devices. Results demonstrated that SFDI offers superior spatial/spectral resolution for mapping tissue oxygenation, particularly in detecting skin-type variations. However, device-specific limitations such as motion artifacts and melanin interference necessitate further optimization. This work supports the development of more inclusive and accurate non-invasive monitoring tools for clinical use.