Clinical evaluation of the new BMU 40 in-line blood analysis monitor

Abstract

Background: Accurate information about different blood parameters is essential in maintaining haemodynamics, perfusion and gas exchange during cardiopulmonary bypass (CPB). For this purpose, precise, accurate and continuous measurement and monitoring, preferably visually available, is needed.The objective of this clinical study was to compare the newly developed continuous in-line blood parameter monitoring system (CIBPMS) BMU 40 with a reference laboratory analyser with regards to the precision and accuracy of blood parameter measurement. Methods: Thirty adult patients underwent elective cardiac surgery, CPB and mild hypothermia (32°C). At five predetermined time points (S1 — S5) arterial and venous blood samples were analysed using the BMU 40 for five different parameters (PaO2(37°C), PaO2(act), SvO2, Hb(ven) and Hct(ven)) and these results were compared to the gold standard laboratory analyser, the ABL 700. Results: A total of 150 paired blood samples were included to compare means, to analyse correlation, and to calculate measures of bias, precision, limits of agreement and 95% confidence intervals. Results revealed good agreement between the two devices for all parameters. Bias ± precision of S2 — S5 PaO 2(37°C) were: 2.17 ± 9.61; PaO2(act) 2.58 ± 9.54; SvO2 -1.44 ± 2.35; Hb(ven) 0.01 ± 0.42; Hct(ven) 0.04 ± 1.29. Statistically significant differences were detected for SvO2 (p<0.00001) at S1. Correlations after this first time point (S1) improved following an in vivo calibration. Conclusion: The BMU 40 is a precise, accurate and reliable continuous in-line blood parameter measuring system that can easily be used within a standard CPB setup. However, present data suggest an in vivo calibration of the BMU 40 should be performed.