Integrated and automatic mixing of whole blood: An evaluation of a novel blood gas analyzer

Background: A homogeneous whole blood specimen is essential to produce quality results from blood gas analysis, however achieving an adequately mixed specimen can be difficult due to the absence of any dead space in a blood gas syringe. This study evaluated the efficacy of an automatic mixing feature incorporated into the ABL800 FLEX blood gas analyzer and estimated the systematic error in tests performed by the instrument. Methods: Quantitative measurements of pH, PCO2, PO2, Na+, K+, Ca+, glucose, lactate, and total hemoglobin were performed on 388 whole blood specimens collected into standard blood gas syringes or specific syringes designed to work in conjunction with the ABL800 FLEX. One hundred eighty specimens were manually or automatically mixed following horizontal storage for 10, 20, or 30 min and total hemoglobin was used as in indicator of specimen homogeneity. Two hundred eight specimens were used to estimate the systematic error of tests performed by the ABL800 FLEX. Results: Manual mixing produced significantly more variation in paired hemoglobin measurements compared to automatic mixing at all three time points (p < 0.0001). All estimates of systematic error were very low and clinically insignificant. Quantitative results showed excellent agreement with a reference analyzer. Conclusions: In contrast to manual mixing, automatic mixing by the ABL800 FLEX consistently produces a homogeneous specimen. (c) 2006 Elsevier B.V. All rights reserved.