To assure adequate pressure recordings the arterial line was repeatedly flushed with 5 ml saline throughout Ponatinib mechanism the observation period and observed for tracing quality.Comparative measurements were performed after induction, after sternotomy, and in the period of graft preparation (GP1 to GP5) before cardiopulmonary bypass. During graft harvesting, arterial blood pressure was titrated in periods of 10 to 15 minutes from a stable baseline around 80 mmHg (GP1 and GP2) to 100 mmHg (GP3) and further to higher than 110 mmHg (GP4) by a continuous infusion of noradrenaline (2.6 ��g/min to 6.6 ��g/min). Thereafter blood pressure was allowed to decrease back to levels around 80 mmHg (GP5).Statistical analysesData analyses were performed by MedCalc 10.4 (MedCalc Software bvba, Mariakerke, Belgium).
Following Kolmogoronov-Smirnov test for normal distribution, data were analyzed parametrically. Between group differences were analyzed by analysis of variance. Intraindividual changes were analyzed by paired Student’s t-test with Bonferoni-adjustment. Correlation analyses were performed by linear regression. Comparisons between methods were performed by Bland-Altman statistics. A P < 0.05 was considered statistically significant.ResultsThe course of CO measurements and MAP is given in Figure Figure1,1, showing significant increases in MAP after sternotomy and during GP 3 and GP 4. No significant changes in IPATD cardac output were observed while FTV CO significantly increased during these blood pressure steps. Heart rate did not change significantly throughout the study period (data not shown).
Figure 1Cardiac output and mean arterial pressure during the study period. The time course of (a) cardiac output (CO) determined by intermittent pulmonary arterial thermodilution (filled circles = IPATD-CO) and autocalibrated pressure waveform analysis with the …Correlation analysis revealed moderate correlations between FTV-CO and IPATD-CO (r = 0.51, 95% confidence interval (CI): 0.35 to 0.64, P < 0.0001) and between MAP and FTV-CO (r = 0.63, 95% CI: 0.49 to 0.74, P < 0.0001) but no correlation between MAP and IPATD-CO. Bland-Altman analyses for FTV-CO versus IPATD-CO revealed a bias 0.4 l/min and limits of agreement from 2.1 to -1.3 l/min for the pooled data (Figure (Figure2).2). The respective percentage results were: bias 8.5%, limits of agreement 42.2% to - 25.3%.
Figure 2Bland-Altmann plot of absolute cardiac output data determined by intermittent pulmonary Carfilzomib arterial thermodilution (IPATD-CO) and autocalibrated pressure waveform analysis with the Flowtrac/Vigileo?-system (FTV-CO) throughout the study. Closed circles …Bland-Altman analyses at the individual data acquisition points are shown in Table Table1,1, showing percentage errors higher than 30% at most measurement points and an increase in bias at the time points with raised MAP.