Accuracy of non-invasive hemoglobin monitoring by pulse CO-oximeter during liver transplantation

BACKGROUND: Hemoglobin level monitoring is essential during liver transplantation (LT) due to substantial blood loss. We evaluated the accuracy of non-invasive and continuous hemoglobin monitoring (SpHb) obtained by a transcutaneous spectrophotometry-based technology (Masimo Corporation, Irvine, CA) compared with conventional laboratory Hb measurement (Hb) during LT . Additionally, we made subgroup analyses for distinct surgical phases that have special features and hemodynamic problems and thus may affect the accuracy of SpHb. METHODS: During LT , blood samples were obtained twice for each of the three phases of LT (pre-anhepatic, anhepatic, and neohepatic) and were analyzed by the central laboratory. The Hb measurements were compared with SpHb obtained at the time of the blood draws. RESULTS : A total of 282 data pairs obtained from 53 patients were analyzed. The SpHb values ranged from 6.9 to 17.7 g/dL, and the Hb values ranged from 5.4 to 17.1 g/dL. The correlation coefficient between SpHb and Hb was 0.73 (P<0.001), and change in SpHb versus change in Hb was 0.76 (P<0.001). The sensitivity value determined using a 4-quadrant plot was 79%. The bias and precision of SpHb to Hb were 0.86±1.58 g/dL; the limits of agreement were -2.25 to 3.96 g/dL. The overall correlation between SpHb and Hb remained stable in different phases of surgical procedure. CONCLUSIONS: SpHb was demonstrated to have a clinically acceptable accuracy of hemoglobin measurement in comparison with a standard laboratory device when used during LT . This technology can be useful as a trend monitor during all surgical phases of LT and can supplement Hb to optimize transfusion decisions or to detect occult bleeding.