title: Comparison between respiratory variations in pulse oximetry plethysmographic waveform amplitude and arterial pulse pressure during major abdominal surgery.
abstract: BACKGROUND
  To assess preload dependence, the variation of the plethysmographic waveform of pulse oximetry (ΔPOP) has been proposed as a surrogate of the pulse pressure variation (ΔPP). The aim of the study was to assess the ability of the pulse oximeter-derived plethysmographic analysis to accurately trend ΔPP in patients undergoing major abdominal surgery by using standard monitors.
  
  
  METHODS
  A continuous recording of arterial and plethysmographic waveform was performed in 43 patients undergoing abdominal surgery. ΔPP and ΔPOP were calculated on validated respiratory cycles.
  
  
  RESULTS
  For analysis, 92,467 respiratory cycles were kept (73.5% of cycles recorded in 40 patients). The mean of intrapatient coefficients of correlation was low (r = 0.22). The Bland and Altman analysis showed a systematic bias of 5.21; the ΔPOP being greater than the ΔPP, this bias increased with the mean value of the two indices and the limits of agreement were wide (upper 21.7% and lower -11.3%). Considering a ΔPP threshold at 12% to classify respiratory cycles as responders and nonresponders, the corresponding best cutoff value of ΔPOP was 13.6 ± 4.3%. Using these threshold values, the observed classification agreement was moderate (κ = 0.50 ± 0.09).
  
  
  CONCLUSIONS
  The wide limits of agreement between ΔPP and ΔPOP and the weak correlation between both values cast doubt regarding the ability of ΔPOP to substitute ΔPP to follow trend in preload dependence and classify respiratory cycles as responders or nonresponders using standard monitor during anesthesia for major abdominal surgery.
authors.affiliation: Department of Anesthesiology and Critical Care, Hôpital de la Croix Rousse, 69317 Lyon, France. baptiste.hengy@orange.fr
authors.forename: Baptiste
authors.initials: B
authors.lastname: Hengy
authors.forename: Mathieu
authors.initials: M
authors.lastname: Gazon
authors.forename: Zoe
authors.initials: Z
authors.lastname: Schmitt
authors.forename: Karima
authors.initials: K
authors.lastname: Benyoub
authors.forename: Aurélie
authors.initials: A
authors.lastname: Bonnet
authors.forename: Jean Paul
authors.initials: JP
authors.lastname: Viale
authors.forename: Frederic
authors.initials: F
authors.lastname: Aubrun
mesh_terms: D000005:Abdomen / Q000601:surgery*; D000368:Aged; D062186:Arterial Pressure / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D010092:Oximetry / Q000379:methods*; D010991:Plethysmography / Q000379:methods*; D015656:Respiratory Mechanics / Q000502:physiology*