“Smart Clothing” technology for heart function monitoring during a session of “dry” immersion

The study aimed at obtaining precise view of modification of heart rate variability (HRV) and respiratory rate with help of “smart clothes” (the Hexoskin Smart Shirt, Hexoskin Smart Sensors & AI, Montreal, QC, Canada) during 45 min session of ground-based microgravity modeled by “dry” immersion (DI). Eight healthy subjects aged from 19 to 21 years participated in the study. Hexoskin Smart Shirt provided a .wav sound file, and the ecg_peaks function of the neurokit2 library was used. The resulting data set of RR intervals on ECG was filtered with cutoff heart rate < 45 and >180 beat per min. HRV parameters were calculated within 5-min segments with help of the pyHRV toolbox. Time-domain (HR, SDNN) and frequency-domain (TP, HF, LF, VLF) HRV parameters, sample and approximate entropy were calculated. The dynamics of HRV parameters and respiratory rate during DI session acquired with “smart” clothes were consistent with those obtained with conventional ECG devices. Thus, the “smart clothes” technology appears as a reliable telemetric instrument to monitor cardiac and respiratory regulation with HRV parameters during the DI session. This technology enabled to continuously monitor HRV parameters under DI, which allowed to evidence that HRV parameters change quite early (within minutes) under DI conditions. This findigs can be appliyed to monitor body functions in extreme environment, inncluding space conditions.