Mixed venous oxygen saturation cannot be estimated by central venous oxygen saturation in septic shock

Objective: Central venous oxygen saturation (ScvO(2)) in initial resuscitation is included in the Surviving Sepsis Campaign guidelines. ScvO(2) monitoring has also been suggested to be comparable to mixed venous oxygen saturation (SvO(2)) for clinical purposes. The aim of our study was to assess the correlation and agreement of ScvO(2) and SvO(2) and compare ScvO(2)-SvO(2) difference to lactate, oxygen-derived and hemodynamic parameters in early septic shock in ICU after initial resuscitation. Design and setting: Prospective clinical study with 16 patients with septic shock at two university hospital ICUs. A dose of norepinephrine over 0.1 mu g/kg/min was required for inclusion. Measurements and results: Five paired ScvO(2) and SvO(2) samples at 6-h intervals, altogether 72 samples, were collected during 24 h. The mean SvO(2) was below the mean ScvO(2) at all time points. Bias of difference was 4.2% and 95% limits of agreement ranged from -8.1% to 16.5%. The difference correlated significantly to CI and DO2. Conclusions: The difference between paired ScvO(2) and SvO(2) varies highly. Therefore, SvO(2) may not be estimated on the basis of ScvO(2) in treatment of septic shock after resuscitation period in ICU.