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Anesthesiology Research and Practice
Volume 2014 (2014), Article ID 980149, 9 pages
Research Article

Calculation of the Respiratory Modulation of the Photoplethysmogram (DPOP) Incorporating a Correction for Low Perfusion

1Covidien Respiratory & Monitoring Solutions, Edinburgh EH26 0PJ, UK
2Department of Anesthesiology, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
3Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA

Received 11 April 2014; Accepted 20 June 2014; Published 7 August 2014

Academic Editor: Ronald G. Pearl

Copyright © 2014 Paul S. Addison et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


DPOP quantifies respiratory modulations in the photoplethysmogram. It has been proposed as a noninvasive surrogate for pulse pressure variation (PPV) used in the prediction of the response to volume expansion in hypovolemic patients. The correlation between DPOP and PPV may degrade due to low perfusion effects. We implemented an automated DPOP algorithm with an optional correction for low perfusion. These two algorithm variants (DPOPa and DPOPb) were tested on data from 20 mechanically ventilated OR patients split into a benign “stable region” subset and a whole record “global set.” Strong correlation was found between DPOP and PPV for both algorithms when applied to the stable data set: for DPOPa/DPOPb. However, a marked improvement was found when applying the low perfusion correction to the global data set: for DPOPa/DPOPb. Sensitivities, Specificities, and AUCs were 0.86, 0.70, and 0.88 for DPOPa/stable region; 0.89, 0.82, and 0.92 for DPOPb/stable region; 0.81, 0.61, and 0.73 for DPOPa/global region; 0.83, 0.76, and 0.86 for DPOPb/global region. An improvement was found in all results across both data sets when using the DPOPb algorithm. Further, DPOPb showed marked improvements, both in terms of its values, and correlation with PPV, for signals exhibiting low percent modulations.