title: Comparison of the accuracy of noninvasive hemoglobin monitoring by spectrophotometry (SpHb) and HemoCue® with automated laboratory hemoglobin measurement.
abstract: BACKGROUND
  The reference method for hemoglobin concentration measurement remains automated analysis in the laboratory. Although point-of-care devices such as the HemoCue® 201+ (HemoCue, Ängelholm, Sweden) provide immediate hemoglobin values, a noninvasive, spectrophotometry-based technology (Radical-7®; Masimo Corp., Irvine, CA) that provides continuous online hemoglobin (SpHb) measurements has been introduced. This clinical study aimed to test the hypothesis that SpHb monitoring was equivalent to that of HemoCue® (the automated hemoglobin measurement in the laboratory taken as a reference method) during acute surgical hemorrhage.
  
  
  METHODS
  Blood for laboratory analysis was sampled after induction of anesthesia, during surgery according to the requirements of the anesthesiologist, and finally after the transfer of the patient to the recovery room. When each blood sample was taken, capillary samples were obtained for analysis with HemoCue®. SpHb monitoring was performed continuously during surgery. Using the automated hemoglobin measurement in the laboratory as a reference method, the authors tested the hypothesis that SpHb monitoring is equivalent to that of HemoCue®. The agreement between two methods was evaluated by linear regression and Bland and Altman analysis.
  
  
  RESULTS
  Eighty-five simultaneous measurements from SpHb, HemoCue®, and the laboratory were obtained from 44 patients. Bland and Altman comparison of SpHb and HemoCue® with the laboratory measurement showed, respectively, bias of -0.02 ± 1.39 g · dl(-1) and -0.17 ± 1.05 g · dl(-1), and a precision of 1.11 ± 0.83 g · dl(-1) and 0.67 ± 0.83 g · dl(-1). Considering an acceptable difference of ± 1.0 g · dl(-1) with the laboratory measurement, the percentage of outliers was significantly higher for SpHb than for HemoCue® (46% vs. 16%, P < 0.05).
  
  
  CONCLUSIONS
  Taking automated laboratory hemoglobin measurement as a reference, the study shows that SpHb monitoring with Radical-7® gives lower readings than does the HemoCue® for assessment of hemoglobin concentration during hemorrhagic surgery.
authors.affiliation: Department of Anesthesiology and Intensive Care, Hôpital Necker-Enfants Malades, Assistance Publique Hôpitaux de Paris, and Université Paris Descartes, Paris, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Lamhaut
authors.forename: Roxana
authors.initials: R
authors.lastname: Apriotesei
authors.forename: Xavier
authors.initials: X
authors.lastname: Combes
authors.forename: Marc
authors.initials: M
authors.lastname: Lejay
authors.forename: Pierre
authors.initials: P
authors.lastname: Carli
authors.forename: Benoît
authors.initials: B
authors.lastname: Vivien
mesh_terms: D000368:Aged; D000758:Anesthesia; D001322:Autoanalysis; D016063:Blood Loss, Surgical / Q000503:physiopathology; D017707:Erythrocyte Transfusion; D005260:Female; D006452:Hemoglobinometry / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009862:Online Systems; D010092:Oximetry; D019095:Point-of-Care Systems; D011997:Recovery Room; D015203:Reproducibility of Results; D013053:Spectrophotometry