title: Central venous saturation in septic shock: co-oximetry vs gasometry.
abstract: OBJECTIVE
  Central venous oxygen saturation calculated by gasometry (Gaso-Scvo2) is more available than central venous oxygen saturation measured by co-oximetry (Co-oxy-Scvo2) in environments with less resources and underdeveloped countries. Therefore, we aimed to determine the agreement between Co-oxy-Scvo2 and Gaso-Scvo2 and between central venous oxygen tension measured by gasometry (Gaso-Pcvo2) and Co-oxy-Scvo2, respectively.
  
  
  METHODS
  This is a prospective study in a university hospital's intensive care unit.
  
  
  METHODS
  Sixteen patients were studied during the first 48 hours after diagnosis of septic shock. All patients were intubated, connected to mechanical ventilation, and resuscitated according to the standards of care.
  
  
  RESULTS
  One hundred eleven pairs of central venous blood measurements were analyzed both by conventional gasometry and co-oximetry. Bland and Altman analysis between Co-oxy-Scvo2 and Gaso-Scvo2 showed lack of agreement (1.7 [-10.7, +14.2]). A Gaso-Scvo2 less than 70% had a positive predictive value of 63% in relation to Co-oxy-Scvo2, and its negative predictive value was 90% with 20% false-positives and 5% false-negatives. The area under the receiver operator characteristic curve of Gaso-Pcvo2 to discriminate a Co-oxy-Scvo2 greater than or equal to 70% was 0.87 (confidence interval, 0.80-0.93), and the best cut-off point was a Gaso-Pcvo2 more than 40 mm Hg, (sensitivity, 75%; specificity, 93%).
  
  
  CONCLUSIONS
  The reliability of Gaso-Scvo2 determination during the resuscitation phase of septic shock is not acceptable. There is a good agreement between a Gaso-Pcvo2 more than 40 mm Hg and a Co-oxy-Scvo2 greater than or equal to 70%. Our results suggest that given these limitations, Gaso-Scvo2 results should be interpreted with caution, helped by Gaso-Pcvo2 measurements and in context with other perfusion parameters.
authors.affiliation: Unidad de Pacientes Críticos, Departamento de Medicina, Hospital Clínico Universidad de Chile, Santiago Norte, Chile. Electronic address: caromero@hcuch.cl.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Romero
authors.affiliation: Unidad de Pacientes Críticos, Departamento de Medicina, Hospital Clínico Universidad de Chile, Santiago Norte, Chile.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Luengo
authors.affiliation: Unidad de Pacientes Críticos, Departamento de Medicina, Hospital Clínico Universidad de Chile, Santiago Norte, Chile.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Tobar
authors.affiliation: Unidad de Pacientes Críticos, Departamento de Medicina, Hospital Clínico Universidad de Chile, Santiago Norte, Chile.
authors.forename: Luis
authors.initials: L
authors.lastname: Fábrega
authors.affiliation: Laboratorio Central, Departamento de Medicina, Hospital Clínico Universidad de Chile, Santiago Norte, Chile.
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Vial
authors.affiliation: Unidad de Pacientes Críticos, Departamento de Medicina, Hospital Clínico Universidad de Chile, Santiago Norte, Chile.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Cornejo
authors.affiliation: Unidad de Pacientes Críticos, Departamento de Medicina, Hospital Clínico Universidad de Chile, Santiago Norte, Chile.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Gálvez
authors.affiliation: Unidad de Pacientes Críticos, Departamento de Medicina, Hospital Clínico Universidad de Chile, Santiago Norte, Chile.
authors.forename: Osvaldo
authors.initials: O
authors.lastname: Llanos
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis / Q000379:methods; D002405:Catheterization, Central Venous; D015331:Cohort Studies; D005260:Female; D006785:Hospitals, University; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000150:complications / Q000175:diagnosis*; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000097:blood*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012772:Shock, Septic / Q000097:blood* / Q000150:complications
chemical_list: D010100:Oxygen