Abstract
BackgroundCardiac output (CO) is a key measure of adequacy of organ and tissue perfusion, especially in critically ill or complex surgical patients. CO monitoring technology continues to evolve. Recently developed CO monitors rely on unique algorithms based on pulse contour analysis of an arterial blood pressure (ABP) waveform. The objective of this investigation was to compare the accuracy of two monitors using different methods of pulse contour analysis – the Retia Argos device and the Edwards Vigileo-FloTrac device – with pulmonary artery catheter (PAC)-thermodilution as a reference.MethodsFifty-eight patients undergoing off-pump coronary artery bypass surgery formed the study cohort. A total of 572 triplets of CO measurements from each device – Argos, Vigileo-FloTrac (third generation), and thermodilution – were available before and after interventions (e.g., vasopressors, fluids, and inotropes). Bland–Altman analysis accounting for repeated measurements per subject and concordance analysis were applied to assess the accuracy of the CO values and intervention-induced CO changes of each pulse contour device against thermodilution. Cluster bootstrapping was employed to statistically compare the root-mean-squared-errors (RMSE = √(μ2 + σ2), where μ and σ are the Bland–Altman bias and precision errors) and concordance rates of the two devices.ResultsThe RMSE (mean (95% confidence intervals)) for CO values was 1.16 (1.00–1.32) L/min for the Argos device and 1.54 (1.33–1.77) L/min for the Vigileo-FloTrac device; the concordance rate for intervention-induced CO changes was 87 (82–92)% for the Argos device and 72 (65–78)% for the Vigileo-FloTrac device; and the RMSE for the CO changes was 17 (15–19)% for the Argos device and 21 (19–23)% for the Vigileo-FloTrac device (p < 0.0167 for all comparisons).ConclusionsIn comparison with CO measured by the PAC, the Argos device proved to be more accurate than the Vigileo-FloTrac device in CO trending and absolute CO measurement in patients undergoing off-pump coronary artery bypass surgery.
Highlights
Cardiac output (CO) is a key measure of adequacy of organ and tissue perfusion, especially in critically ill or complex surgical patients
In comparison with CO measured by the pulmonary artery catheter (PAC), the Argos device proved to be more accurate than the Vigileo-FloTrac device in CO trending and absolute CO measurement in patients undergoing off-pump coronary artery bypass surgery
A total of 572 triplets of Argos, Vigileo-FloTrac, and thermodilution CO values as well as 509 corresponding triplets of intervention-induced changes in consecutive CO values (ΔCO = 100⋅(COafter—CObefore)/CObefore) from 58 patients were included in this study for secondary analysis
Summary
Cardiac output (CO) is a key measure of adequacy of organ and tissue perfusion, especially in critically ill or complex surgical patients. The pulse contour-based devices permit continuous CO monitoring via mathematical analysis of a peripheral arterial blood pressure (ABP) waveform [1] Some of these devices detect pulse pressure as a marker of stroke volume and multiply the pulse pressure with heart rate to compute the ratio of CO to the arterial compliance [2, 3]. Arterial wave reflection may cause the peripheral pulse pressure to change irrespective of stroke volume due to vasoconstriction or vasodilation and may obscure exponential diastolic decays in peripheral ABP waveforms While these devices have been extensively tested in human subjects, accuracy still remains a concern [1, 5,6,7]. None of the devices have emerged as being more accurate than another
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