RT Journal Article SR Electronic T1 Standard pulse oximeters can be used to monitor respiratory rate JF Emergency Medicine Journal JO Emerg Med J FD BMJ Publishing Group Ltd and the British Association for Accident & Emergency Medicine SP 524 OP 525 DO 10.1136/emj.20.6.524 VO 20 IS 6 A1 P Leonard A1 T F Beattie A1 P S Addison A1 J N Watson YR 2003 UL http://emj.bmj.com/content/20/6/524.abstract AB Background: One of the most important limitations of standard pulse oximeters is the inability to detect changes in respiratory rate until oxygenation is affected. This study sought to determine if analysis of the plethysmogram by wavelet transforms would enable the determination of changes in respiratory rate at an earlier stage. Methods: Ten healthy adult volunteers were monitored, breathing at baseline and predetermined respiratory rates, using a standard pulse oximeter. Photo-plethysmograms captured in an attached lap top computer were then analysed using wavelet transforms. Results: Determination of baseline respiratory rate and subsequent changes including apnoea were easily identified. Comment: Wavelet transforms permit the accurate determination of respiratory rate by a standard pulse oximeter.