Breathing Rate
Last updated
Last updated
Breathing rate (BR) corresponds to the number of times the user inhales and exhales, expressed as a rate per minute (Range: up to 50 breaths/minute). 12-25 breaths/minute is considered healthy/normal.
BR measured by BitDoctor was assessed against BR as measured with a respiration belt. All tests were conducted by researchers with experience in data collection, signal processing, and machine learning.
Over 10,000 test subjects took part in the test. The subjects were recruited from the Affiliated Hospital of Hangzhou Normal University in China and the University of Toronto in Canada. There were no exclusion criteria when recruiting participants, although most participants were healthy adults above 18 years of age. Table 9 displays a summary of participant characteristics.
Average Age
41.2
Standard deviation of age
15.2
Gender distribution
48% Male; 52% Female
Table 9: Characteristics of participants for breathing
A mechanical respiration belt was attached around the thoracic region of each participant and then connected to a Biopac recording device. Figure 12 depicts the data collection setup.
Oscillations in the tension of the respiration belt (capturing inspiration and expiration) and video recordings of the participant’s face were captured in a 2-minute recording.
Reference BR was calculated by counting the number of breathing cycles (inspiration + expiration) captured by the respiration belt, and then expressing this value as a per-minute rate.
BitDoctor-based BR was calculated by using the breathing detection algorithm to predict the number of breaths based on facial blood flow information, and then expressing this value as a per-minute rate.
Breathing rate accuracy was then expressed as a Pearson correlation between participants’ reference breathing rate (as determined by respiration belt/BIOPAC) and breathing rate estimated by BitDoctor.
The accuracy and reliability of BitDoctor BR is summarized in Table 10.
Breathing
>90
99
Table 10: Accuracy and reliability of BitDoctor BR.
The Pearson correlation between participants’ reference BR (as determined via respiration belt/BIOPAC) and BR estimated by BitDoctor was r=0.9. Figure 13 depicts the relation between reference BR (ground truth) and BitDoctor BR (predicted value)
Figure 13: Scatter plot depicting the relation between reference (ground truth) BR measured with a respiration belt and BR estimated from BitDoctor. The equation characterizes the line of best fit.
