Comparison of the ability of esCCO and Volume View to measure trends in cardiac output in patients undergoing cardiac surgery

Abstract

Background: Cardiac output (CO) is a physiological variable that should be monitored during cardiac surgery. The purpose of this study was to assess the trending ability of two CO monitors, esCCO (Nihon Kohden™, Tokyo, Japan) and Volume View (VV) (Edwards Lifesciences, Irvine, USA).

Methods: A total of 19 patients were included in the study. Before cardiopulmonary bypass (CPB), CO was measured simultaneously using both esCCO and VV devices before and after three CO-modifying manoeuvres (passive leg raise [PLR], the end expiratory occlusion test [EEOT] and positive end expiratory pressure [PEEP] at 10 cm H₂O). Five CO values for esCCO and three for VV were averaged and compared during a one-minute period of time before and after each manoeuvre.

Results: A total of 114 paired readings were collected. Median CO values were 4.3 L min⁻¹ (IQR: 3.8; 5.2) and 3.8 L min⁻¹ (IQR: 3.5; 4.5) for esCCO and VV, respectively. The precision error was 1.4% (95% CI:1.0-1.7) for esCCO and 2.2% (95% CI: 1.8-2.7) for VV. The bias between esCCO and VV values was normally distributed (P = 0.0596). Between esCCO and VV, the mean bias was +0.6 L min⁻¹ with a Limit of Agreement (LOA) of -1.8 L min⁻¹ and +3.0 L min⁻¹. The concordance rate was 43% (95% CI: 29-58) between esCCO and VV.

Conclusion: Both single and trended measurements of CO using esCCO and VV were not in agreement. This large discrepancy leads one to the conclusion that any outcome study conducted with one of these devices cannot be applied to the other.

Keywords: cardiac output; cardiac surgery; general anaesthesia; non-invasive monitoring.