Central venous saturation is not an alternative to mixed venous saturation during cardiopulmonary bypass in coronary artery surgery patients

Background:To evaluate the correlation and agreement between central venous saturation (ScvO2) and mixed venous saturation (SvO2) during cardiopulmonary bypass.Methods:Twenty-two consecutive patients scheduled for coronary artery surgery were prospectively included. Paired measurements of ScvO2 and SvO2 were performed 5 minutes after aortic cross-clamping, after each cardioplegia dose and after de-clamping of the aortic cross-clamp. ScvO2 and SvO2 were measured, respectively, by a fibreoptic catheter in the superior vena cava and on blood samples from the venous return line of the extracorporeal circuit, using a blood gas analyserResults:Ninety-five paired measurements of venous saturation were obtained. Correlation between the measurements was associated with an r = 0.55. The mean bias was 2.2 [Limits of agreement: –13.6%, +18%]. Changes in oxygen saturation over time showed an r = 0.4 and a mean bias of 0.2 [Limits of agreement: –17.9%, +18.3%]. Multivariate analysis identified the oxygen consumption in...