Respiratory rate assessments using a dual-accelerometer device

Monitoring of respiration-related thoracic movements may be useful to assess respiratory rate (RR) objectively. RR was measured during spontaneous breathing, voluntarily modified breathing, and exercise hyperpnoea in normal subjects via visual inspection, spirometry and a pair of accelerometers positioned on the torso. Spirometric and accelerometric values of RR recorded during relaxed breathing were (mean ± SD) 21.44 ± 1.41 bpm and 21.06 ± 2.17 bpm; during voluntarily augmented breathing, these values rose to 29.44 ± 4.61 bpm and 29.23 ± 5.33 bpm, respectively; spirometric and accelerometric RR values did not differ in any of the cases. RR assessment was unaffected by recumbence. During handgrip, spirometric (16.43 ± 3.10 bpm) and accelerometeric (16.22 ± 2.76 bpm) control RR values did not differ and increased to comparable levels (24.22 ± 7.30 and 24.82 ± 5.45 bpm, respectively) by the end of exercise. At rest, visual (18.94 ± 3.45 bpm) and accelerometric (19.27 ± 3.83 bpm) RR values were compliant in normal subjects as well as in scoliotic and obese patients. Accelerometers are a reliable tool for monitoring RR, during both eupnoea and stressed breathing.