Two Methods of Hemodynamic and Volume Status Assessment in Critically Ill Patients: A Study of Disagreement

Introduction: The invasive nature and potential complications associated with pulmonary artery (PA) catheters (PACs) have prompted the pursuit of less invasive monitoring options. Before implementing new hemodynamic monitoring technologies, it is important to determine the interchangeability of these modalities. This study examines monitoring concordance between the PAC and the arterial waveform analysis (AWA) hemodynamic monitoring system. Methods: Critically ill patients undergoing hemodynamic monitoring with PAC were simultaneously equipped with the FloTrac AWA system (both from Edwards Lifesciences, Irvine, California). Data were concomitantly obtained for hemodynamic variables. Bland-Altman methodology was used to assess CO measurement bias and κ coefficent to show discrepancies in intravascular volume. Results: Significant measurement bias was observed in both CO and intravascular volume status between the 2 techniques (mean bias,'1.055 ± 0.263 liter/min, r = 0.481). There was near-complete lack of agreement regarding the need for intravenous volume administration (κ = 0.019) or the need for vasoactive agent administration (κ = 0.015). Conclusions: The lack of concordance between PAC and AWA in critically ill surgical patients undergoing active resuscitation raises doubts regarding the interchangeability and relative accuracy of these modalities in clinical use. Lack of awareness of these limitations can lead to errors in clinical decision making when managing critically ill patients.