High central venous saturation after cardiac surgery is associated with increased organ failure and long-term mortality: an observational cross-sectional study

INTRODUCTION: Central venous saturation (S(cv)O(2)) monitoring has been suggested to address the issue of adequate cardiocirculatory function in the context of cardiac surgery. The aim of this study was to determine the impact of low (L) (<60%), normal (N) (60%-80%), and high (H) (>80%) S(cv)O(2) measured on intensive care unit (ICU) admission after cardiac surgery. METHODS: We conducted a retrospective, cross-sectional, observational study at three ICUs of a university hospital department for anaesthesiology and intensive care. Electronic patient records of all adults who underwent cardiac surgery between 2006 and 2013 and available admission measurements of S(cv)O(2) were examined. Patients were allocated to one of three groups according to first S(cv)O(2) measurement after ICU admission: group L (<60%), group N (60%-80%), and group H (>80%). Primary end-points were in-hospital and 3-year follow-up survival. RESULTS: Data from 4,447 patients were included in analysis. Low and high initial measurements of S(cv)O(2) were associated with increased in-hospital mortality (L: 5.6%; N: 3.3%; H: 6.8%), 3-year follow-up mortality (L: 21.6%; N: 19.3%; H: 25.8%), incidence of post-operative haemodialysis (L: 11.5%; N: 7.8%; H: 15.3%), and prolonged hospital length of stay (L: 13 days, 9–22; N: 12 days, 9–19; H: 14 days, 9–21). After adjustment for possible confounding variables, an initial S(cv)O(2) above 80% was associated with adjusted hazard ratios of 2.79 (95% confidence interval (CI) 1.565-4.964, P <0.001) for in-hospital survival and 1.31 (95% CI 1.033-1.672, P = 0.026) for 3-year follow-up survival. CONCLUSIONS: Patients with high S(cv)O(2) were particularly affected by unfavourable outcomes. Advanced haemodynamic monitoring may help to identify patients with high S(cv)O(2) who developed extraction dysfunction and to establish treatment algorithms to improve patient outcome in these patients. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13054-015-0889-6) contains supplementary material, which is available to authorized users.