Usability of a multi-sensor array for the application of electro-phonocardiography in home care

In the latest years, the potentiality of a combined use of electrocardiography (ECG) and phonocardiography (PCG) for the assessment of the electromechanical coupling of the heart has gained interest within the scientific community. The availability of this technology in a home care context would enable the timely monitoring of patients where the electromechanical coupling is impaired, such as in heart failure. Nevertheless, the domiciliary use of electro-phonocardiography is at date prevented by the critical positioning of the electronic stethoscope, which cannot be reliably performed by inexperienced users. In this work, we propose a usability analysis of a multi-sensor array that we developed for this purpose. The multi-sensor array is a flexible pad embedding 3 electrodes and 48 microphones, distributed over the left hemithorax with a high spatial resolution. In our experimental protocol, we simulated a real home care scenario: volunteers with no technical nor clinical skills were enrolled in couples and alternatively performed the recordings on each other, simulating the roles of patient and caregiver. Results show that a Signal-to-Noise Ratio (SNR) higher that 13 dB was always achieved, even before any digital filtering. Moreover, the influence of the body structure of the patient, quantified in terms of Body Mass Index and thoracic circumference, on the quality of the signals was assessed. A moderate significant negative correlation was found, as expected, but in the overall the body structure did not prevent from obtaining reliable signals even in cases of severe overweight. We believe that the presented findings lay the foundations for the use of electro-phonocardiography in telemonitoring applications.