title: Diagnostic accuracy of central venous saturation in estimating mixed venous saturation is proportional to cardiac performance among cardiac surgical patients.
abstract: OBJECTIVE
  Advanced hemodynamic monitoring in cardiac surgery translates into improvement in outcomes. We evaluated the relationship between central venous (ScvO2) and mixed venous (SvO2) saturations over the early postoperative period. The adequacy of their interchangeability was tested in patients with varying degrees of cardiac performance.
  
  
  METHODS
  In this prospective observational study, we evaluated 156 consecutive cardiac surgical patients in an academic center. The ScvO2 and SvO2 data were harvested from 468 paired samples taken preoperatively (T0), after weaning from cardiopulmonary bypass (T1) and on postoperative day 1 (T2).
  
  
  RESULTS
  The relationship between ScvO2 and SvO2 was inconsistent, with inferior correlations in patients with lower cardiac indices (CI) (Pearson r(2) = 0.37 if CI ≤2.0 L/min per square meter vs r(2) = 0.73 if CI >2.0 L/min per square meter, both P < .01). Patients with lower CI also had wider 95% limits of agreement between SvO2 and ScvO2. The proportion of patients with a negative SvO2-ScvO2 gradient increased over time (48/156 [31%] at T0 to 73/156 [47%] at T2; P < .01). This subgroup more frequently required inotropes at T2 than patients with a positive SvO2-ScvO2 gradient (odds ratio, 6.46 [95% confidence interval, 0.81-51.87], P = .06) and also had higher serum lactate levels (1.5 ± 0.8 vs 1.0 ± 0.4; P < .01).
  
  
  CONCLUSIONS
  The diagnostic accuracy of ScvO2 for estimating SvO2 is proportional to cardiac performance. A negative SvO2-ScvO2 gradient at T2 correlated with inotropic support requirement, higher operative risk score, age, lactate level, and duration of cardiopulmonary bypass.
authors.affiliation: Department of Cardiac Surgery, University Hospital Center Zagreb, University of Zagreb, Zagreb, Croatia. Electronic address: hgasparovic@gmail.com.
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Gasparovic
authors.affiliation: Department of Anesthesiology, University Hospital Center Zagreb, University of Zagreb, Zagreb, Croatia.
authors.forename: Rajka
authors.initials: R
authors.lastname: Gabelica
authors.affiliation: Department of Cardiac Surgery, University Hospital Center Zagreb, University of Zagreb, Zagreb, Croatia.
authors.forename: Zvonimir
authors.initials: Z
authors.lastname: Ostojic
authors.affiliation: Department of Cardiac Surgery, University Hospital Center Zagreb, University of Zagreb, Zagreb, Croatia.
authors.forename: Tomislav
authors.initials: T
authors.lastname: Kopjar
authors.affiliation: Department of Cardiac Surgery, University Hospital Center Zagreb, University of Zagreb, Zagreb, Croatia.
authors.forename: Mate
authors.initials: M
authors.lastname: Petricevic
authors.affiliation: Department of Anesthesiology, University Hospital Center Zagreb, University of Zagreb, Zagreb, Croatia.
authors.forename: Visnja
authors.initials: V
authors.lastname: Ivancan
authors.affiliation: Department of Cardiac Surgery, University Hospital Center Zagreb, University of Zagreb, Zagreb, Croatia.
authors.forename: Bojan
authors.initials: B
authors.lastname: Biocina
mesh_terms: D000328:Adult; D000368:Aged; D002303:Cardiac Output, Low / Q000097:blood* / Q000503:physiopathology; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D002407:Catheterization, Swan-Ganz / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D010100:Oxygen / Q000097:blood*; D011184:Postoperative Period; D011446:Prospective Studies; D015203:Reproducibility of Results; D013815:Thermodilution / Q000379:methods
chemical_list: D010100:Oxygen
keywords: Cardiac surgery; Central venous saturation; Mixed venous saturation; Pulmonary artery catheter