title: Agreement of central venous saturation and mixed venous saturation in cardiac surgery patients.
abstract: OBJECTIVE
  Comparison of the bias and the limits of agreement (LOA; 2 SD) of the central venous saturation (S(cv)O(2)) before, during and after coronary artery bypass graft surgery with a simultaneous measurement of the mixed venous saturation (S(v)O(2)).
  
  
  METHODS
  Prospective controlled study in a university hospital department of anaesthesiology.
  
  
  METHODS
  60 patients with coronary artery bypass surgery, 300 paired measurements of S(v)O(2) and S(cv)O(2).
  
  
  RESULTS
  S(cv)O(2) and S(v)O(2) were analysed after induction of anaesthesia 15 min after cardiopulmonary bypass and 1, 6 and 18 h after admission to the intensive care unit. Regression analysis for the pooled measurements of S(cv)O(2) and S(v)O(2) showed a correlation R (2) = 0.52. After induction of anaesthesia 15 min after weaning from cardiopulmonary bypass and 6 h after admission to the intensive care unit the correlation coefficient was R (2) = 0.46, on admission to the intensive care unit it was R (2) = 0.42, and at 18 h it was R (2) = 0.38. Bland-Altman analysis for the measurements of S(cv)O(2) and S(v)O(2) showed a mean bias and LOA of 0.3% and -11.9 to +12.4%. In patients with a low S(cv)O(2) there was a trend to overestimate the S(v)O(2) by using the S(cv)O(2). The only factor that influenced the DeltaS(v)O(2) - S(cv)O(2) was the oxygen extraction rate (R (2) = 0.16). In patients with S(cv)O(2) below 70% this association was more pronounced (R (2) = 0.60).
  
  
  CONCLUSIONS
  Our findings demonstrate that oxygen extraction rate is the major factor in the difference between S(v)O(2) and S(cv)O(2). Under certain circumstances S(cv)O(2) differed substantially from S(v)O(2). Therefore in selected patients both parameters should be monitored to exclude general or focal hypoperfusion.
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital Charité, Campus Charité Mitte/Campus Virchow Klinikum, Charité Universitätsmedizin, Charitéplatz 1, 10098, Berlin, Germany. michael.sander@charite.de
authors.forename: Michael
authors.initials: M
authors.lastname: Sander
authors.forename: Claudia D
authors.initials: CD
authors.lastname: Spies
authors.forename: Achim
authors.initials: A
authors.lastname: Foer
authors.forename: Lisa
authors.initials: L
authors.lastname: Weymann
authors.forename: Jan
authors.initials: J
authors.lastname: Braun
authors.forename: Thomas
authors.initials: T
authors.lastname: Volk
authors.forename: Herko
authors.initials: H
authors.lastname: Grubitzsch
authors.forename: Christian
authors.initials: C
authors.lastname: von Heymann
mesh_terms: D000368:Aged; D001026:Coronary Artery Bypass; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D019990:Perioperative Care; D011446:Prospective Studies; D014680:Veins
chemical_list: D010100:Oxygen