title: Continuous noninvasive hemoglobin monitor from pulse ox: ready for prime time?
abstract: BACKGROUND
  Advances in technology have allowed for continuous noninvasive hemoglobin monitoring (SpHb), which may enable earlier detection of hemorrhage and more efficient surgical and/or blood transfusion management. The use of SpHb has not been described in the trauma population. The purpose of the present study was to evaluate the accuracy of a SpHb measurement device in severely injured trauma patients.
  
  
  METHODS
  We performed a prospective cohort analysis of severely injured trauma patients admitted to the intensive care unit (ICU) at our level I trauma center over a 6 month period. Serial IHb (invasive hemoglobin) levels and SpHb for the first 72 h were measured. Each SpHb measurement was matched with a corresponding IHb measurement. We defined normal Hgb as >8 mg/dL and low Hgb as <8 mg/dL. Data were then grouped based on Hgb level. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and Spearman correlation coefficient plot were calculated.
  
  
  RESULTS
  A total of 23 trauma patients with 89 data pairs were reviewed. Eighty-six percent of the patients were male with a mean age of 32 years and a mean injury severity score (ISS) of 21.1 ± 14. Invasive hemoglobin had a range of 7.2-16.9 and SpHb had a range of 3.3-15.2. The average mean and difference between IHb and SpHb were 10.7 and 1, respectively. Continuous noninvasive hemoglobin measurement did not record data points 13.5% of the time. The Spearman correlation plot revealed a correlation of R = 0.670 (p < 0.001). After dichotomization with Hgb > 8, SpHb was found to have a sensitivity of 91%, PPV 96%, specificity 40%, NPV 20%, and an accuracy of 88%.
  
  
  CONCLUSIONS
  The continuous noninvasive hemoglobin monitor does not appear to represent serum hemoglobin levels accurately in severely injured trauma patients. However, we were able to identify utility for this noninvasive tool when Hgb was dichotomized into normal or low levels.
authors.affiliation: Department of Surgery, University of Arizona, Tucson, AZ, USA. bjoseph@surgery.arizona.edu
authors.forename: Bellal
authors.initials: B
authors.lastname: Joseph
authors.forename: Pantelis
authors.initials: P
authors.lastname: Hadjizacharia
authors.forename: Hassan
authors.initials: H
authors.lastname: Aziz
authors.forename: Kara
authors.initials: K
authors.lastname: Snyder
authors.forename: Julie
authors.initials: J
authors.lastname: Wynne
authors.forename: Narong
authors.initials: N
authors.lastname: Kulvatunyou
authors.forename: Andrew
authors.initials: A
authors.lastname: Tang
authors.forename: Terence
authors.initials: T
authors.lastname: O'Keeffe
authors.forename: Rifat
authors.initials: R
authors.lastname: Latifi
authors.forename: Randall
authors.initials: R
authors.lastname: Friese
authors.forename: Peter
authors.initials: P
authors.lastname: Rhee
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006454:Hemoglobins / Q000032:analysis*; D006470:Hemorrhage / Q000097:blood* / Q000209:etiology; D006801:Humans; D015601:Injury Severity Score; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D010092:Oximetry / Q000295:instrumentation*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014947:Wounds and Injuries / Q000150:complications* / Q000175:diagnosis; D055815:Young Adult
chemical_list: D006454:Hemoglobins