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Evaluation of a wearable device based on inertial sensors for non-invasive monitoring of respiratory rate changes in patients with muscular dystrophies: a pilot study

Doctor in charge: Dr.ssa Maria Grazia D'Angelo, Dr.ssa Sandra Gandossini
Neuromuscular Unit IRCCS Eugenio Medea, Bosisio Parini

RScientific Coordinator: Prof. Andrea Aliverti
Department of Electronics, Information and Bioengineering, Politecnico di Milano

Main investigator: Ing Ambra Cesareo
IRCCS Eugenio Medea, Bosisio Parini and Department of Electronics, Information and Bioengineering, Politecnico di Milano

Respiratory rate is a vital parameter used to monitor the health status of a subject, both healthy and affected by chronic diseases, whose importance as a prognostic and predictive index has been widely documented in the literature (Cohen et al., 1982; Pardee et al., 1984; Browning et al., 1990; Fieselmann et al., 1993; Subbe et al., 2003; Gravelyn et al., 1980; McFadden et al., 1982). An accurate and prolonged measurement of respiratory rate even outside the clinical setting could provide valuable information on the health status of patients, especially if at risk of cardiac and/or respiratory complications.

To this end, the Department of Electronics, Information and Bioengineering of the Politecnico di Milano has designed and developed RespirHó, a wearable, wireless, and low-cost device for prolonged monitoring (over 24-48 hours) of the respiratory rate, which could be a tool to support the clinician, continuously monitoring the clinical condition of the patient, providing early warnings of early decompensation and allowing, therefore, to intervene by setting follow-ups in a strategic way.

Abnormalities in respiratory rate, which can be detected by continuous monitoring, can be an early marker to help the clinician schedule thorough evaluations and intervene before respiratory dysfunction and/or failure sets in.

The methods and instruments currently used in clinical practice or proposed in the literature for the measurement of respiratory rate have not yet established themselves as standard assessment methods and, above all, most of them are not appropriate for a continuous and prolonged monitoring of respiratory rate outside the clinical environment, due to their invasive and/or intrusive nature. In recent years, the technology of wearable devices has tried to respond to the need for continuous monitoring of vital parameters and among these also of respiratory activity by proposing new technologies; among these, the one based on the use of single or tri-axial accelerometers worn on the chest or abdomen has demonstrated the ability to measure the respiratory rate in different postures and to discern between different pathological respiratory patterns (Hung S. et al., 2008.; Yin B. et al., 2009; Bates A. et al., 2010.; Liu G.Z et al. 2011; Mann J. Et al., 2011; Fekr R. et al. 2014). However, these studies raised the problem of using a single accelerometer in dynamic conditions due to the motion artifacts introduced, a problem that was partially solved by introducing fusion algorithms using data from accelerometer, gyroscope and magnetometer (Gollee H. & Chen W. 2007; Yoon J. W. Et al., 2014).

Based on these elements, the Department of Electronics, Information and Bioengineering of the Politecnico di Milano has developed RespirHó, a modular and wearable device based on the detection of abdominal and thoracic movements through the use of inertial sensors (accelerometer, gyroscope, triaxial magnetometer). RespirHó aims at improving the problem of motion artifacts in the measurement of respiratory rate using inertial sensors, and proposes itself as a respiratory holter system. RespirHó consists of three small units, two of which (41x33x19 mm, 25 g) to be positioned on the chest and abdomen and the third (43x49x19, 35 g) to be positioned as a reference on an area of the body not subject to respiratory movements but integral to the trunk (e.g. on the coccyx) or wheelchair.

Primary objective: To evaluate any further steps in the development of the device, including design changes with respect to safety, usability, and effectiveness of the device in assessing changes in respiratory rate and other temporal parameters related to respiratory activity in wheelchair-bound muscular dystrophy patients.

Secondary objective: v evaluate the acceptability of the proposed technology to the target population.

The study is a pilot study, i.e., a clinical investigation carried out to acquire preliminary information regarding a wearable device for continuous monitoring of respiratory rate (i.e., RespirHó) in order to adequately plan further stages of its development, including design changes.

The clinical investigation plan has a total duration of 6 months and foresees the recruitment of 15 patients affected by Duchenne muscular dystrophy (LGMD type 2) and confined in wheelchair recruited at UO Neuromuscular IRCCS E. Medea.

The study will consist of the following phases:

  1. Enrollment in accordance with established inclusion and exclusion criteria;
  2. Collection of patient's anamnestic data, registration of current pharmacological therapies, registration of use of cough and ventilation support devices; clinical and instrumental evaluations.
  3. Device testing under static conditions in an outpatient setting: thoraco-abdominal kinematics measurements with RespirHó device and Optoelectronic Plethysmography
  4. Testing of the device under dynamic, long-term conditions during daily activities. Patients will be asked to wear the device during normal daily activities, for up to 24 hours.
  5. Questionnaires: the patient will be asked to fill in questionnaires to assess the wearability and usability of the device and technological acceptance.
  6. data analysis.
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