title: Audio signal feedback light source-guided endotracheal intubation.
abstract: OBJECTIVE
  Light source-guided endotracheal intubation, whether by lighted stylet or fiber-optic laryngoscopy may potentially be improved by electrical conversion of the detected optical signal to an audio signal. The audio signal thus serves as a feedback guiding signal.
  
  
  METHODS
  The optical-to-audio signal conversion is accomplished using a light source, an optical detector and a voltage-to-frequency conversion system. The intensity of the detected optical signal determines the frequency of the audio-signal. Therefore the frequency of the audio signal varies as the light source approaches the optical detector. The light source may be placed in the orotracheal airway and the detector may be placed on cricothyroid membrane or these components may be placed in the opposite orientation.
  
  
  RESULTS
  The theory of operation and the construction of a prototype are described.
  
  
  CONCLUSIONS
  This optical-audio signal feedback system may be used to direct the lighted stylet from the oral cavity into the laryngeal-tracheal pathway. This may potentially be a more sensitive technique than the currently used visual intensity detection.
authors.affiliation: University of Arizona Health Sciences Center Department of Anesthesiology, Tucson 85724, USA.
authors.forename: S
authors.initials: S
authors.lastname: Yang
mesh_terms: D000162:Acoustics / Q000295:instrumentation; D000669:Amplifiers, Electronic; D003413:Cricoid Cartilage / Q000033:anatomy & histology; D004582:Electronics, Medical / Q000295:instrumentation; D004867:Equipment Design; D005246:Feedback; D005336:Fiber Optic Technology / Q000295:instrumentation; D006801:Humans; D007442:Intubation, Intratracheal / Q000295:instrumentation / Q000379:methods*; D020704:Laryngoscopes; D007828:Laryngoscopy / Q000379:methods; D007830:Larynx / Q000033:anatomy & histology; D008027:Light; D009055:Mouth / Q000033:anatomy & histology; D055100:Optical Fibers; D009991:Oscillometry / Q000295:instrumentation; D013016:Sound; D013957:Thyroid Cartilage / Q000033:anatomy & histology; D014132:Trachea / Q000033:anatomy & histology