Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. Photographs of (a) a prism attached to an optical fiber prior to fabrication of the esophageal probe and (b) the finished probe. Figure Legend: From: Photoplethysmographic measurements from the esophagus using a new fiber-optic reflectance sensor J. Biomed. Opt. 2011;16(7): doi: /

Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. Simplified diagram of the fiber-optic esophageal oximetry probe. Approximate dimensions shown in millimeters. Figure Legend: From: Photoplethysmographic measurements from the esophagus using a new fiber-optic reflectance sensor J. Biomed. Opt. 2011;16(7): doi: /

Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. Esophageal probe inserted into a size 18 French gauge stomach feeding tube. Figure Legend: From: Photoplethysmographic measurements from the esophagus using a new fiber-optic reflectance sensor J. Biomed. Opt. 2011;16(7): doi: /

Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. Example of a 100-s recording of the dc (a) and normalized ac PPG (b) infrared and red signals at all five measurement depths for one patient (patient number = 17). Figure Legend: From: Photoplethysmographic measurements from the esophagus using a new fiber-optic reflectance sensor J. Biomed. Opt. 2011;16(7): doi: /

Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. Thirty-second samples of the normalized ac PPG waveforms obtained at each measurement depth. The waveforms were obtained from the same data set shown in Fig.. All traces are plotted on the same vertical scale. Figure Legend: From: Photoplethysmographic measurements from the esophagus using a new fiber-optic reflectance sensor J. Biomed. Opt. 2011;16(7): doi: /

Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. Graphs showing mean (± SEM) dc signal levels (a) and the unnormalized mean (± SEM) peak-to-peak amplitudes of the ac PPG signals (b) plotted against depth in the esophagus for all 19 patients. Figure Legend: From: Photoplethysmographic measurements from the esophagus using a new fiber-optic reflectance sensor J. Biomed. Opt. 2011;16(7): doi: /

Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. Graph showing normalized mean (± SEM) peak-to-peak amplitude of ac red and infrared PPG signals measured from the esophagus in 19 patients. Figure Legend: From: Photoplethysmographic measurements from the esophagus using a new fiber-optic reflectance sensor J. Biomed. Opt. 2011;16(7): doi: /