title: Near-Infrared Spectroscopy Hemoglobin Index Measurement During Fluid Challenge: A Prospective Study in Cardiac Surgery Patients.
abstract: OBJECTIVE
  Little is known about changes in near-infrared spectroscopy-derived tissue hemoglobin index (HbI). The authors tested the hypothesis that absolute values and changes in brain hemoglobin index (HbIb) and skeletal muscle hemoglobin index (HbIm) could differ from the reference arterial hemoglobin (Hb) during fluid challenge.
  
  
  METHODS
  A prospective, monocenter observational study.
  
  
  METHODS
  A 16-bed cardiac surgical intensive care unit in a teaching university hospital.
  
  
  METHODS
  Fifty consecutive adult patients.
  
  
  METHODS
  Investigation before and after a fluid challenge.
  
  
  RESULTS
  Simultaneous comparative Hb, HbIb and HbIm data points were collected from a blood-gas analyzer and the EQUANOX device (Nonin Medical Inc., Plymouth, MN). Correlations were determined by linear regression. No significant relationship was found between absolute values of Hb and HbIb before (R(2)= 0.04, p = 0.627) and after (R(2) = 0.00006, p = 0.956) fluid challenge. No significant relationship was found between absolute values of Hb and HbIm before (R(2)= 0.030, p = 0.226) and after (R(2) = 0.05, p = 0.117) the fluid challenge. No significant relationship was found between changes in Hb and HbIb (R(2)= 0.26, p = 0.263) and between changes in Hb and HbIm (R(2) = 0.001, p = 0.801) after the fluid challenge. Bland-Altman analysis showed a poor concordance between changes in Hb and HbIb, and changes in Hb and HbIm, with large limits of agreement.
  
  
  CONCLUSIONS
  HbIb and HbIm cannot be used to provide continuous noninvasive estimation of Hb, and trends in HbIb and HbIm cannot be considered as noninvasive surrogates for the trend in Hb after cardiac surgery.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, CHU de Caen, Caen, F-14000, France; Univ Caen, Faculty of Medicine, Caen, F-14000, France. Electronic address: rebet-o@chu-caen.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: Rebet
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, CHU de Caen, Caen, F-14000, France; Univ Caen, Faculty of Medicine, Caen, F-14000, France.
authors.forename: Marc-Olivier
authors.initials: MO
authors.lastname: Fischer
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, CHU de Caen, Caen, F-14000, France; Univ Caen, Faculty of Medicine, Caen, F-14000, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Zamparini
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, CHU de Caen, Caen, F-14000, France; Univ Caen, Faculty of Medicine, Caen, F-14000, France.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Gérard
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, CHU de Caen, Caen, F-14000, France; Univ Caen, Faculty of Medicine, Caen, F-14000, France.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Fellahi
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, CHU de Caen, Caen, F-14000, France; Univ Caen, Faculty of Medicine, Caen, F-14000, France.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Hanouz
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D001784:Blood Gas Analysis / Q000379:methods / Q000639:trends; D006348:Cardiac Surgical Procedures / Q000379:methods / Q000639:trends*; D005260:Female; D005440:Fluid Therapy / Q000379:methods / Q000639:trends*; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019265:Spectroscopy, Near-Infrared / Q000379:methods / Q000639:trends*
chemical_list: D015415:Biomarkers; D006454:Hemoglobins
keywords: cardiac surgery; fluid challenge; hemoglobin; monitoring; near-infrared spectroscopy; tissue hemoglobin concentration