Validation of Spectrophotometric Hemoglobin Measurement with a Pulse Co-Oximeter in Cases of Massive Hemorrhage

Abstract

Purpose: The accuracy of spectrophotometric hemoglobin (SpHb) measurement with a pulse co-oximeter was analyzed in cases of intraoperative massive hemorrhage and compared with Hb levels determined through blood gas analysis (LabHb) as a reference. We aimed to determine the extent to which in vivo adjustment (ADJ) for results of initial blood gas analysis would improve the accuracy of SpHb measurement. Methods: Data on LabHb and SpHb levels were collected from cases with hemorrhage of 1000 g or more. Correlations and Bland-Altman analyses were used to determine the associations between data before and after ADJ. Results: ADJ slightly improved the correlation coefficient (Pearson r) between SpHb and LabHb levels from 0.65 to 0.72. In Bland-Altman analysis, ADJ reduced the bias from 1.76 ± 1.47 g/dL to 0.64 ± 1.43 g/dL, while the 95% limits of agreement of -1.12 to 4.64 g/dL (range: 5.77 g/dL) without ADJ improved to -2.16 to 3.44 g/dL (range: 5.59 g/dL) with ADJ. In four-quadrant analysis, other than samples in the exclusion zone, the total number analyzed was 326, and the concordance rate was 82%. Conclusion: Although the accuracy of SpHb measurement improves on ADJ, SpHb measurement cannot substitute for LabHb levels, and it is necessary to determine Hb levels with blood gas analysis in the laboratory. It remains unclear which measurement is superior for determining when to initiate blood transfusion to achieve better outcomes. To comply with conventional methods, LabHb measurements may be necessary.