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Downward bias of conductivity based point-of-care hemoglobin measurement compared with optical methods
Anesth Pain Med 2018;13(3):323-8
Published online July 31, 2018
© 2018 The Korean Society of Anesthesiologists.

Min Hee Heo1, Jun Hyun Kim1 , Kyung Woo Kim2, Ho Jae Cho1, Won Joo Choe1, Kyung-Tae Kim1, Ji Yeon Kim1, Sang-Il Lee1, Jang Su Park1, and Jung Won Kim1
1Department of Anesthesiology and Pain Medicine, Inje University Ilsan Paik Hospital, Goyang, 2Department of Anesthesiology and Pain Medicine, Inje University Seoul Paik Hospital, Seoul, Korea
Correspondence to: Jun Hyun Kim, M.D. Department of Anesthesiology and Pain Medicine, Inje University Ilsan Paik Hospital, 170 Juhwa-ro, Ilsanseo-gu, Goyang 10380, Korea Tel: 82-31-910-7067 Fax: 82-31-910-7184 E-mail: ORCID
Received September 7, 2017; Revised November 25, 2017; Accepted November 27, 2017.
cc This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background: Point-of-care (POC) arterial blood gas analysis (ABGA) is widely used for checking hemoglobin (Hb) level. However, there is the tendency of downward bias of conductivity-based POC ABGA Hb measurement compared with optical methods. Authors tried to correct that bias by linear regression equation.
Methods: We retrospectively collected a total of 86 Hb result pairs during surgeries. Hb measured by the Sysmex XE-2100 in the laboratory was set as the gold standard and was compared with that measured by the GEM Premier 3500. Data were compared using the Bland-Altman analysis, the reliability of transfusion decision was assessed using three-zone error grid. The linear regression analysis was performed to find out the relation between the Hb results of POC ABGA and those of laboratory based test.
Results: The bias of the Hb measured between Sysmex XE-2100 and GEM Premier 3500 was −0.9 g/dl (P < 0.001, 95% confidence interval, −1.038 to −0.665 g/dl). The percentage error was 16.4%. According to error grid methodology, zone A, B and C encompassed 89.5%, 10.5% and 0% of data pairs. After adjusting the POC ABGA Hb values, the bias of the Hb measured by two methods was 0 g/dl (P = 0.991). The percentage error was 18.2%. The zone A, B and C encompassed 91.9%, 8.1% and 0% of data pairs.
Conclusions: Hb measurements obtained with reference to conductivity via a POC ABGA were significantly lower than those obtained via optical methods. This bias may deserve attention of anesthesiologists when POC ABGA Hb level is used as a transfusion guideline.
Key Words : Blood gas analysis, Hemoglobins, Point-of-care testing.

July 2018, 13 (3)
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