Correlation between central venous oxygen saturation and oxygen delivery changes following fluid therapy.

BACKGROUND The rationale for using central venous oxygen saturation (ScvO(2)) in various clinical scenarios is that it reflects the balance between oxygen delivery (DO(2)) and demands. In this study, we evaluated the correlation between ScvO(2) and DO(2) changes (Delta Do(2), DeltaScvO(2)) in patients receiving fluid therapy following coronary surgery. We also correlated the changes of mean arterial pressure (Delta MAP) and central venous pressure (Delta CVP), with Delta DO(2). METHODS Sixty consecutive sedated and mechanically ventilated adult patients, with cardiac index <or=2.3 L/min/m(2) and a pulmonary artery occlusion pressure <or=12 mmHg following coronary surgery, were included. Concomitant hemodynamic parameters, arterial and venous blood gases were measured before (T0) and after (T1) administration of a 500 ml bolus of an isotonic crystalloid solution over 30 min. The correlations between Delta DO(2) and DeltaScvO(2), Delta MAP or Delta CVP were evaluated by linear regression analysis and Pearson test. RESULTS Cardiac index (1.9+/-0.2 vs 2.3+/-0.5 ml/min/m(2)), MAP (83+/-11 vs 94+/-13 mm Hg) and CVP (5.7+/-3 vs 7.1+/-3 mmHg) were significantly higher at T1 compared with T0. The correlation of Delta DO(2) with DeltaScvO(2) was positive, significant (r=0.41; P=0.004) and superior to its correlation with Delta MAP (r=0.30; P=0.01) or Delta CVP (r=0.03; P=0.78). CONCLUSION A significant correlation between ScvO(2) and DO(2) changes was found in patients receiving fluid therapy following coronary surgery. ScvO(2) could be used as an indicator to track DO(2) and to guide volume loading.