Methodological Recommendations for the Creation of Sensor Measurement Systems for Respiratory Rate Monitoring Based on Photoplethysmographic Signal Processing

A methodical apparatus for creating sensor measurement systems for monitoring human respiration rate is proposed. It includes a method for estimating respiratory rate based on statistical analysis of photoplethysmographic signals (human pulse wave), a method for selecting priority regions for estimating respiratory rate, and a criterion for determining the required bracelet tension during measurements. The application of the respiratory rate estimation method involves calculating the Correntropy spectral density of the pulse wave signal. A distinctive feature of the method is the use of an algorithm for selecting the priority empirical mode of the Hilbert-Huang decomposition, which is most closely related to the respiratory rate. Experimental verification of the method showed that the mean value of the absolute error for 58.8% of the sample of calculated respiratory rate values did not exceed 1 breath/min, and the 95% confidence interval for the mean absolute error of the entire sample was [0.72–2.2] breaths/min.