In-field use of I-VED electrical impedance sensor for assessing post-dive decompression stress in humans
Authors:   Department of Chemical Technology and Industrial Chemistry, Faculty of Chemistry, Aristotle University, University Box 116, 541 24 Thessaloniki, Greece, Evgenidis, PhD. Sotiris P , Zacharias, PhD Konstantinos ,   Department of Chemical Technology and Industrial Chemistry, Faculty of Chemistry, Aristotle University, University Box 116, 541 24 Thessaloniki, Greece,   Physical Measurements Department, Hellenic Institute of Metrology, National Quality Infrastructure System, Block 45, 57022, Sindos, Thessaloniki, Greece, Papadopoulou, PhD Virginie ,   Department of Bioengineering, Imperial College of London, London, UK,   Environmental & Occupational (Integrative) Physiology Laboratory, Haute Ecole Bruxelles-Brabant (HE2B), Brussels, Belgium,   Joint Department of Biomedical Engineering, The University of North Carolina at Chapel Hill and North Carolina State University, NC, USA, Theunissen, PhD Sigrid ,   Environmental & Occupational (Integrative) Physiology Laboratory, Haute Ecole Bruxelles-Brabant (HE2B), Brussels, Belgium, Balestra, PhD Costantino ,   Environmental & Occupational (Integrative) Physiology Laboratory, Haute Ecole Bruxelles-Brabant (HE2B), Brussels, Belgium, Karapantsios, PhD Thodoris D ,   Department of Chemical Technology and Industrial Chemistry, Faculty of Chemistry, Aristotle University, University Box 116, 541 24 Thessaloniki, Greece
Published: April 2024

Purpose: Ultrasound imaging is commonly used in decompression research to assess venous gas emboli (VGE) post-dive, with higher loads associated with increased decompression sickness risk. This work examines, for the first time in humans, the performance of a novel electrical impedance spectroscopy technology (I-VED), on possible detection of post-dive bubbles presence and arterial endothelial dysfunction that may be used as markers of decompression stress. Methods: I-VED signals were recorded in scuba divers who performed standardized pool dives before and at set time points after their dives at 35-minute intervals for about two hours. Two distinct frequency components of the obtained signals, Low-Pass Frequency-LPF: 0-0.5 Hz and Band-Pass Frequency-BPF: 0.5-10 Hz, are extracted and respectively compared to VGE presence and known flow-mediated dilation trends for the same dive profile for endothelial dysfunction. Results: Subjects with VGE counts above the median for all subjects were found to have an elevated average LPF compared to subjects with lower VGE counts, although this was not statistically significant (p=0.06), as well as significantly decreased BPF standard deviation post-dive compared to pre-dive (p=0.008). Conclusions: I-VED was used for the first time in humans and operated to provide qualitative in-vivo electrical impedance measurements that may contribute to the assessment of decompression stress. Compared to ultrasound imaging, the proposed method is less expensive, not operator-dependent and compatible with continuous monitoring and application of multiple probes. This study provided preliminary insights; further calibration and validation are necessary to determine I-VED sensitivity and specificity.