Hemoglobin test result variability and cost analysis of eight different analyzers during open heart surgery

The purpose of this study was to compare the variation in hemoglobin (Hgb) values among various point-of-care (POC) analyzers available on the market. Eight analyzers (Gem 3000, ABL 720, ABL 77, Rapidpoint 405, IL 682, GemOPL, Hb 201+, and manual/centrifugation) were compared with the Hgb values from the Beckman Coulter LH750. A total of 72 patient samples were analyzed on each test instrument. The samples were obtained after intubation, after heparinization, during cardiopulmonary bypass, and after protamine administration. Four of the samples were excluded from the study because of delayed sample analysis. The calculated mean differences of reference test method Hgb (mean +/- SD) for all samples (n = 68) were Gem 3000 = 1.431 +/- 0.396 g/dL; ABL 720 = -0.224 +/- 0.240 g/dL; ABL 77 = 0.341 +/- 0.578 g/dL; Rapidpoint 405 = 0.001 +/- 0.205 g/dL; IL 682 = -0.137 +/- 0.232 g/dL; GemOPL = 0.774 +/- 0.427 g/dL; Hb 201+ = 0.110 +/- 0.524 g/dL; and manual/ centrifugation = 0.547 +/- 0.499 g/dL. Cumulative results indicated that the bias in Hgb values from the Gem 3000, ABL720, ABL 77, IL 682, GemOPL, and the manual method were statistically significant (p < .05), compared with the Coulter LH750. Additionally, only the Rapidpoint 405 and Hb 201+ most closely matched the values from the Coulter LH750 (p > .05). Some of the methodologies have previously been shown to be affected during hemodilution, hypoproteinemia, and/or after blood transfusion. There is variability among methodologies, which can give rise to statistically different Hgb values, and one should consider the "ideal" instrument based on this and many other factors. Based on our results, the rank order of closest approximation to the Coulter LH750 measurement was Rapidpoint 405, Hb 201+, IL 682, ABL 720, ABL 77, manual/centrifugation, GemOPL, and Gem 3000.