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Noninvasive Continuous Hemoglobin Monitoring in Combat Casualties: A Pilot Study

Bridges, Elizabeth; Hatzfeld, Jennifer J.

doi: 10.1097/SHK.0000000000000654
Clinical Aspects

Objective: To describe the accuracy and precision of noninvasive hemoglobin measurement (SpHb) compared with laboratory or point-of-care Hb, and SpHb ability to trend in seriously injured casualties.

Methods: Observational study in a convenience sample of combat casualties undergoing resuscitation at two US military trauma hospitals in Afghanistan. SpHb was obtained using the Masimo Rainbow SET (Probe Rev E/Radical-7 Pulse CO-Oximeter v Clinically indicated Hb was analyzed with a Coulter or iStat and compared with simultaneous SpHb values.

Results: Twenty-three patients were studied (ISS 20 ± 9.8; age 29 ± 9 years; male 97%; 100% intubated). Primary injury cause: improvised explosive device (67%) or gunshot (17%). There were 49 SpHb-Hb pairs (median 2 per subject). Bias: 0.3 ± 1.6 g/dL (95% LOA −2.4, 3.4 g/dL). The SpHb-Hb difference < ± 1 g/dL in 37% of pairs. Eighty-six percent of pairs changed in a similar direction. Using an absolute change in Hb of >1 g/dL, a concurrent absolute change in SpHb of >1 g/dL had a sensitivity: 61%, specificity 85%, positive predictive value: 80%, and a negative predictive value: 69%. The SpHb signal was present in 4643 of 6137 min monitored (76%).

Conclusions: This was the first study to describe continuous SpHb in seriously injured combat casualties. Using a threshold of 1 g/dL previously specified in the literature, continuous SpHb is not precise enough to serve as sole transfusion trigger in trauma patients. Further research is needed to determine if it is useful for trending Hb changes or as an early indicator of deterioration in combat casualties.

*Biobehavioral Nursing and Health Systems, University of Washington School of Nursing, Seattle, Washington

Defense Medical Research and Development Program Combat Casualty Care, Research (MRMC-RTC), Fort Detrick, Maryland

Address reprint requests to Elizabeth Bridges, PhD, RN, CCNS, Biobehavioral Nursing and Health Systems, University of Washington School of Nursing, 1959 NE Pacific, Seattle, WA 98103. E-mail:

Received 27 February, 2016

Revised 25 March, 2016

Accepted 11 May, 2016

The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Air Force, Department of the Army, or the Department of Defense.

This study was supported by a grant from the TriService Nursing Research Program N05-P05: Arterial Based and Non-Invasive Functional Hemodynamic Indices in Combat Trauma Resuscitation.

Preliminary results of this study were presented at the USAF Military Research Symposium (Aug 2010) and the Society for Critical Care Medicine—Critical Care Congress (Jan 2012).

The authors report no conflicts of interest.

© 2016 by the Shock Society