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Muscle Oxygen Saturation Improves Diagnostic Association Between Initial Vital Signs and Major Hemorrhage: A Prospective Observational Study
Author(s) -
Reisner Andrew T.,
Edla Shwetha,
Liu Jianbo,
Rubin John T.,
Thorsen Jill E.,
Kittell Erin,
Smith Jason B.,
Yeh Daniel D.,
Reifman Jaques
Publication year - 2016
Publication title -
academic emergency medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.221
H-Index - 124
eISSN - 1553-2712
pISSN - 1069-6563
DOI - 10.1111/acem.12899
Subject(s) - medicine , vital signs , confidence interval , blood pressure , receiver operating characteristic , heart rate , logistic regression , observational study , pulse oximetry , emergency department , oxygen saturation , prospective cohort study , area under the curve , anesthesia , cardiology , surgery , oxygen , chemistry , organic chemistry , psychiatry
Objectives 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 (SmO 2 ), 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 SmO 2 , 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 SmO 2 added independent information beyond routine vital signs, we developed one logistic regression model with HR , sBP , and PP and one with SmO 2 in addition to HR , sBP , and PP and compared their areas under receiver operating characteristic curves ( ROC AUC s) using DeLong's test. Results We enrolled 487 subjects; 23 received 24‐hr RBC ≥ 3. Compared to the model without SmO 2 , the regression model with SmO 2 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 AUC s predicting patients ( n = 11) receiving 24‐hr RBC ≥ 9. Conclusions SmO 2 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.