Assessment of trending ability by polar plot methodology between central venous and mixed venous oxygen saturation which were measured concurrently by spectrophotometry

Abstract

Objective: We studied the trending ability and the correlation between central venous oxygen saturation (ScvO₂) and mixed venous oxygen saturation (SvO₂); they were measured concurrently by spectrophotometry. The purpose of this study was to determine whether ScvO₂ could be exploited as a hemodynamic monitor after the removal of a pulmonary artery catheter. Methods: After arrival at the ICU, we measured and recorded ScvO₂ and SvO₂ continuously. We selected the pairs of ScvO₂ and SvO₂, which showed a value of 1 or 2 on signal quality indicator, and examined the trending ability and the correlation between the two. Results: The data of 24 adult patients who underwent cardiac surgery were examined. As the result, the range of the coefficient of correlation was 0.12-0.85 and showed great dispersion between cases. And individual case had different bias. It was only 2 cases to have shown good trending ability. Conclusions: Since the correlation between ScvO₂ and SvO₂ were different by cases respectively and there were few cases showing good trending ability, we should regard ScvO₂ as a hemodynamic index which was different from SvO₂.