Feasibility Analysis of a Portable Diaphragmatic Efficiency Monitor for CSCI Patients

Objective: This study evaluates the feasibility of a noninvasive system for monitoring diaphragmatic efficiency in people with cervical spinal cord injury (CSCI). Methods: Two versions of a portable hardware system were developed using impedance pneumography (IP) to measure tidal volume (TV) and surface electromyography (sEMG) to assess diaphragm electrical activity (EAdi). Version 1 was used to determine optimal electrode positions, while Version 2 integrated these sensor systems into a compact, portable design. Data from eight healthy male participants were analyzed to assess the correlation and accuracy of TV and respiration rate (RR) prediction using IP and the correlation between sEMG signals and maximum inspiratory pressure (MIP). Results: For IP, measurements between the upper sternum and the midclavicular line (MCL) at the 4th intercostal (IC) space showed the highest correlation with true tidal volume. For sEMG, measurements between the mid-sternum and the 6th IC space demonstrated the strongest correlation with MIP. The integrated version 2 hardware demonstrates simultaneous IP and sEMG measurement while dissipating 2.17 mW. Discussion/Conclusion: The proposed system and the results presented may lead to a practical, cost-effective solution for continuous diaphragmatic efficiency monitoring, and thus enabling home-based respiratory care of CSCI patients.