title: Pulse oximetry and photoplethysmographic waveform analysis of the esophagus and bowel.
abstract: OBJECTIVE
  This article reviews the development of novel reflectance pulse oximetry sensors for the esophagus and bowel, and presents some of the techniques used to analyze the waveforms acquired with such devices.
  
  
  RESULTS
  There has been much research in recent years to expand the utility of pulse oximetry beyond the simple measurement of arterial oxygen saturation from the finger or earlobe. Experimental sensors based on reflectance pulse oximetry have been developed for use in internal sites such as the esophagus and bowel. Analysis of the photoplethysmographic waveforms produced by these sensors is beginning to shed light on some of the potentially useful information hidden in these signals.
  
  
  CONCLUSIONS
  The use of novel reflectance pulse oximetry sensors has been successfully demonstrated. Such sensors, combined with the application of more advanced signal processing, will hopefully open new avenues of research leading to the development of new types of pulse oximetry-based monitoring techniques.
authors.affiliation: Anaesthetic Laboratory, St Bartholomew's Hospital, UK. j.p.phillips@qmul.ac.uk
authors.forename: Justin P
authors.initials: JP
authors.lastname: Phillips
authors.forename: Panayiotis A
authors.initials: PA
authors.lastname: Kyriacou
authors.forename: Deric P
authors.initials: DP
authors.lastname: Jones
authors.forename: Kirk H
authors.initials: KH
authors.lastname: Shelley
authors.forename: Richard M
authors.initials: RM
authors.lastname: Langford
mesh_terms: D001794:Blood Pressure / Q000502:physiology; D004947:Esophagus / Q000098:blood supply; D005546:Forehead; D005583:Fourier Analysis; D006801:Humans; D007422:Intestines / Q000098:blood supply; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods; D010092:Oximetry / Q000295:instrumentation / Q000379:methods; D017156:Photoplethysmography; D012119:Respiration