The clinical significance of central venous oxygen saturation monitoring in the patients after cardiac operation

Abstract

Objective To investigate the clinical significance of central venous oxygen saturation (ScvO2) monitoring in the patients after cardiac operation.Methods Fifty patients after cardiac operation were randomly selected into this study.After the patients entered ICU 2 h,ScvO2,mixed venous oxygen saturation (S(v)vO2),lactate (Lac) were detected at the same time and oxygen extraction rate (O2ER) was calculated.Fifty patients were divided into three groups according to the level of ScvO2,group A (ScvO2 ＜0.65,23 patients),group B (ScvO2 0.65-0.75,18 patients),group C (ScvO2 ＞ 0.75,9 patients).The correlation among ScvO2,S(v)vO2,O2ER were analyzed.The correlation between ScvO2 and Lac in each group were calculated.The level of Lac in three groups were compared.The incidence rate of complications,ventilator time and ICU stay time were compared.Results The level of ScvO2,S（v）O2,O2ER,Lac in 50patients were 0.656 ±0.086,0.639 ±0.081,0.356 ±0.084,(2.6 ± 1.3) mmol/L.The level of ScvO2 had significantly positive correlation with S(v)O2 (r =0.688,P ＜ 0.01),and had significantly negative correlation with O2ER (r =-0.640,P ＜0.01).In group A,the level of Lac had significantly negative correlation with ScvO2 (r =-0.772,P ＜ 0.01).In group C,the level of Lac had significantly positive correlation with ScvO2 (r =0.717,P ＜ 0.05).In group B,the level of Lac had no significant correlation with ScvO2 (r =-0.358,P ＞0.05).The level of Lac in group A and group C was significantly higher than that in group B [(2.0 ± 0.9),(4.8 ±2.1) mmol/L vs.(1.6 ±0.5) mmol/L] (P ＜0.05 or ＜0.01).The incidence rate of hyoxemia,low cardiac output syndrome and renal functional lesion in group A were significantly higher than those in group B (P ＜ 0.05).The incidence rate of liver functional lesion and renal functional lesion in group C were significantly higher than those in group B (P ＜ 0.05).The ventilator time and ICU stay time in group A andgroup C were significantly longer than those in group B (P ＜ 0.05).Conclusions ScvO2 is an ideal index to judge oxygen equilibrium in early period after cardiac operation.The lower and supranormal ScvO2 both suggest tissue hypoxia,resulting in increased postoperative complications and prolonged treatment. Key words: Lactic acid; Postoperative complications; Central venous oxygen saturation; Mixed venous oxygen saturation; Oxygen extraction rate