Monitoring: Equipment and Computers
Background and Goal of study: Central venous oxygen saturation (ScvO2) may be an interesting alternative to mixed venous oxygen saturation (SvO2) in patients without a need of a pulmonary artery catheter (1). The aim of this study was to evaluate the relation between SvO2 and ScvO2 in patients scheduled for cardiac surgery with cardiopulmonary bypass (CPB).
Materials and methods: 33 patients (10 patients with coronary artery bypass grafting (CABG), 7 patients with valve replacement and CABG, 16 patients with valve replacement) after written and informed consent were included in this prospective study. A TCI remifentanil - propofol - cisatracurium anaesthesia was used. Tip placement of the catheters in the pulmonary artery (Swan-Ganz®, 7,5F, American Edwards Lab) and in the superior vena cava (7F triple lumen, Arrow®) was controlled by Transesophageal Echocardiography. Blood samples were drawn at induction (T1), 10 minutes after CPB (T2) and after arrival in the intensive care unit (T3). The blood samples were immediately analysed for oxygen saturation by Instrumentation Laboratory 682 CO-Oximeter. Statistical analysis was performed by linear regression, Pearson correlations and the method of Passing and Bablok (2).
Results: Mean values ± SD, correlations (R) and confidence limits of 95% for SvO2 and ScvO2 at T1, T2 and T3:
The test of Passing Bablok shows that ScvO2 overestimates SvO2 during the 3 sample times.
Conclusions: ScvO2 can not be substituted for SvO2 in cardiac surgery with cardiopulmonary bypass.
1 Rivers EP, et al. NEJM 2001; 345:1368-77.
2 Passing H. J. Clin. Chem. Clin. Biochem.1983; 21: 709-20.