Introduction or background

Efficient, accurate, practical and low-cost methods for long-lasting measurement of respiratory rate (RR) and chest wall motion assessment are still missing in clinical care.

Aims and objectives

We developed a low-cost and simple wearable sensor to assess RR and ventilatory motion based on a combined gyroscope-accelerometre device. Our pilot study is aimed at evaluating the effectiveness and the reliability of this tool for tidal breathing continuous monitoring in healthy population.

Methods

The study involved 10 healthy (males=5) volunteers, selected upon permission of our ethical board. The sensor was placed along the 6^th rib at the right anterior axillary line. In addition to RR, considered movements included latero-lateral (i.e., caliper motion or Droll) and dorso-ventral displacement (i.e., bucket handle or Dpitch) plus acceleration (a). Subjects were trained to correctly place the sensor by themselves and were told to start the recording just prior to night rest, lying in supine position. The device was programmed to extrapolate 1 every 20 minutes along the global 6-hour recording. Data were expressed as median and interquartile range.

Results

Measured median RR was 12 acts/min (11.75-17). Angular changes for each axis were Droll=0.74 (0.60-1.03) deg, Dpitch=0.92 (0.75-1.11) deg, a_min=9.6 (9.52-9.81) m/s² and a_max=9.81 (9.61-9.90) m/s². Despite the relatively small sample size, distribution resulted normal in all the investigated parametres. Subject satisfaction was 8 (7.25-9) over a maximum of 10.

Conclusions

The proposed device allowed for self-evident measurement and continuous record of RR and chest motion parametres. Data were simple, reliable and reproducible.