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

Central venous oxygen saturation (ScvO2) in initial resuscitation is included in the Surviving Sepsis Campaign guidelines. ScvO2 monitoring has also been suggested to be comparable to mixed venous oxygen saturation (SvO2) for clinical purposes. The aim of our study was to assess the correlation and agreement of ScvO2 and SvO2 and compare ScvO2-SvO2 difference to lactate, oxygen-derived and hemodynamic parameters in early septic shock in ICU after initial resuscitation.

Prospective clinical study with 16 patients with septic shock at two university hospital ICUs. A dose of norepinephrine over 0.1 microg/kg/min was required for inclusion.

Five paired ScvO2 and SvO2 samples at 6-h intervals, altogether 72 samples, were collected during 24 h. The mean SvO2 was below the mean ScvO2 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.

The difference between paired ScvO2 and SvO2 varies highly. Therefore, SvO2 may not be estimated on the basis of ScvO2 in treatment of septic shock after resuscitation period in ICU.