title: Wavelet analysis of pulse oximeter waveform permits identification of unwell children.
abstract: BACKGROUND
  Children who are unwell often display signs of circulatory compromise. It has been observed that pronounced changes occur in the appearance of the photoplethysmogram (pulse oximeter tracing) in these children. The aim of the study was to discover if wavelet transforms can identify more subtle changes in the photoplethysmogram of children who are unwell.
  
  
  METHODS
  Photoplethysmograms were obtained from children attending a paediatric accident and emergency department with clinical features suggestive of significant bacterial illness or circulatory compromise. Photoplethysmograms were also obtained from a control group of well children. Wavelet transforms were applied to the traces in an attempt to separate the two groups.
  
  
  RESULTS
  20 traces were obtained from unwell children and 12 from controls. Analysis of the entropy of the wavelet transform of the photoplethysmogram allows the differentiation of unwell children from controls (p = 0.00002).
  
  
  CONCLUSIONS
  Wavelet transform of the photoplethysmogram offers the possibility of a rapid non-invasive method of screening children for significant illness.
authors.affiliation: Department of Accident and Emergency Medicine, The Royal Hospital for Sick Children, Edinburgh, Scotland. paul_leonard@blueyonder.co.uk
authors.forename: P
authors.initials: P
authors.lastname: Leonard
authors.forename: T F
authors.initials: TF
authors.lastname: Beattie
authors.forename: P S
authors.initials: PS
authors.lastname: Addison
authors.forename: J N
authors.initials: JN
authors.lastname: Watson
mesh_terms: D001785:Blood Gas Monitoring, Transcutaneous; D016022:Case-Control Studies; D002648:Child; D003627:Data Interpretation, Statistical; D003933:Diagnosis; D004630:Emergencies; D006801:Humans; D008432:Mathematical Computing