In this work, a state-of-the-art bed-side monitor combining time-domain near infrared spectroscopy and diffuse correlation spectroscopy to measure hemoglobin and blood flow oscillations in the skeletal muscle microvasculature. We focused on very low-frequency and low-frequency oscillations (frequencies below 0.145 Hz), which are associated with myogenic, neurogenic, and endothelial activities. The power spectral density of blood flow and hemoglobin concentration was measured in four muscles (thenar eminence, plantar fascia, sternocleidomastoid, and forearm) of 14 healthy volunteers by Politecnico di Milano. Additionally, we compared the PSDs measured in the thenar eminence of healthy subjects to those measured in a septic patient in the intensive care unit. The data used in this study are read from binary files produced by the platform. These binary files follow a pre-determined format, allowing them to be easily read and processed using various platforms such as MATLAB, Python, and R. The data processing involves then importing the data from these files, followed by appropriate preprocessing steps to ensure appropriate data quality of the displayed data. Preprocessing involves several key steps to prepare the data for analysis. First, movement artifacts are removed. Next, data alignment is performed to synchronize time-series data and to perform power spectral density calculation.

Matlab, 2021b