A fully automated algorithm for the determination of respiratory rate from the photoplethysmogram.
OBJECTIVE
To determine if an automatic algorithm using wavelet analysis techniques can be used to reliably determine respiratory rate from the photoplethysmogram (PPG).


METHODS
Photoplethysmograms were obtained from 12 spontaneously breathing healthy adult volunteers. Three related wavelet transforms were automatically polled to obtain a measure of respiratory rate. This was compared with a secondary timing signal obtained by asking the volunteers to actuate a small push button switch, held in their right hand, in synchronisation with their respiration. In addition, individual breaths were resolved using the wavelet-method to identify the source of any discrepancies.


RESULTS
Volunteer respiratory rates varied from 6.56 to 18.89 breaths per minute. Through training of the algorithm it was possible to determine a respiratory rate for all 12 traces acquired during the study. The maximum error between the PPG derived rates and the manually determined rate was found to be 7.9%.


CONCLUSIONS
Our technique allows the accurate measurement of respiratory rate from the photoplethysmogram, and leads the way for developing a simple non-invasive combined respiration and saturation monitor.
Department of Accident and Emergency Medicine, The Royal Hospital for Sick Children, Sciennes Rd, Edinburgh EH9 1LF, UK. paul_leonard@blueyonder.co.uk
Paul A
PA
Leonard
J Graham
JG
Douglas
Neil R
NR
Grubb
David
D
Clifton
Paul S
PS
Addison
James N
JN
Watson
D000328:Adult; D000465:Algorithms; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D010092:Oximetry / Q000379:methods; D017156:Photoplethysmography / Q000379:methods*; D019095:Point-of-Care Systems; D015656:Respiratory Mechanics / Q000502:physiology*