title: Muscle Oxygen Saturation Improves Diagnostic Association Between Initial Vital Signs and Major Hemorrhage: A Prospective Observational Study.
abstract: OBJECTIVE
  During initial assessment of trauma patients, vital signs do not identify all patients with life-threatening hemorrhage. We hypothesized that a novel vital sign, muscle oxygen saturation (SmO2 ), could provide independent diagnostic information beyond routine vital signs for identification of hemorrhaging patients who require packed red blood cell (RBC) transfusion.
  
  
  METHODS
  This was an observational study of adult trauma patients treated at a Level I trauma center. Study staff placed the CareGuide 1100 tissue oximeter (Reflectance Medical Inc., Westborough, MA), and we analyzed average values of SmO2 , systolic blood pressure (sBP), pulse pressure (PP), and heart rate (HR) during 10 minutes of early emergency department evaluation. We excluded subjects without a full set of vital signs during the observation interval. The study outcome was hemorrhagic injury and RBC transfusion ≥ 3 units in 24 hours (24-hr RBC ≥ 3). To test the hypothesis that SmO2 added independent information beyond routine vital signs, we developed one logistic regression model with HR, sBP, and PP and one with SmO2 in addition to HR, sBP, and PP and compared their areas under receiver operating characteristic curves (ROC AUCs) using DeLong's test.
  
  
  RESULTS
  We enrolled 487 subjects; 23 received 24-hr RBC ≥ 3. Compared to the model without SmO2 , the regression model with SmO2 had a significantly increased ROC AUC for the prediction of ≥ 3 units of 24-hr RBC volume, 0.85 (95% confidence interval [CI], 0.75-0.91) versus 0.77 (95% CI, 0.66-0.86; p < 0.05 per DeLong's test). Results were similar for ROC AUCs predicting patients (n = 11) receiving 24-hr RBC ≥ 9.
  
  
  CONCLUSIONS
  SmO2 significantly improved the diagnostic association between initial vital signs and hemorrhagic injury with blood transfusion. This parameter may enhance the early identification of patients who require blood products for life-threatening hemorrhage.
authors.affiliation: Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Reisner
authors.affiliation: Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research & Materiel Command, Fort Detrick, MD.
authors.forename: Shwetha
authors.initials: S
authors.lastname: Edla
authors.affiliation: Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research & Materiel Command, Fort Detrick, MD.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA.
authors.forename: John T
authors.initials: JT
authors.lastname: Rubin
authors.affiliation: Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA.
authors.forename: Jill E
authors.initials: JE
authors.lastname: Thorsen
authors.affiliation: Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA.
authors.forename: Erin
authors.initials: E
authors.lastname: Kittell
authors.affiliation: Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research & Materiel Command, Fort Detrick, MD.
authors.forename: Jason B
authors.initials: JB
authors.lastname: Smith
authors.affiliation: Department of Surgery, Massachusetts General Hospital, Boston, MA.
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Yeh
authors.affiliation: Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research & Materiel Command, Fort Detrick, MD.
authors.forename: Jaques
authors.initials: J
authors.lastname: Reifman
mesh_terms: D000328:Adult; D004636:Emergency Service, Hospital; D017707:Erythrocyte Transfusion; D005260:Female; D006470:Hemorrhage / Q000175:diagnosis* / Q000628:therapy; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology*; D010092:Oximetry / Q000379:methods*; D011446:Prospective Studies; D012372:ROC Curve; D014193:Trauma Centers; D055986:Vital Signs