title: Femoral-based central venous oxygen saturation is not a reliable substitute for subclavian/internal jugular-based central venous oxygen saturation in patients who are critically ill.
abstract: BACKGROUND
  Central venous oxygen saturation (Scv(O(2))) has been used as a surrogate marker for mixed venous oxygen saturation (Sv(O(2))). Femoral venous oxygen saturation (Sfv(O(2))) is sometimes used as a substitute for Scv(O(2)). The purpose of this study is to test the hypothesis that these values can be used interchangeably in a population of patients who are critically ill.
  
  
  METHODS
  We conducted a survey to assess the frequency of femoral line insertion during the initial treatment of patients who are critically ill. Scv(O(2)) vs Sfv(O(2)) STUDY: Patients with femoral and nonfemoral central venous catheters (CVCs) were included in this prospective study. Two sets of paired blood samples were drawn simultaneously from the femoral and nonfemoral CVCs. Blood samples were analyzed for oxygen saturation and lactate.
  
  
  RESULTS
  One hundred and fifty physicians responded to the survey. More than one-third of the physicians insert a femoral line at least 10% of the time during the initial treatment of patients who were critically ill. Scv(O(2)) vs Sfv(O(2)) STUDY: Thirty-nine patients were enrolled. The mean Scv(O(2)) and Sfv(O(2)) were 73.1% +/- 11.6% and 69.1% +/- 12.9%, respectively (P = .002), with a mean bias of 4.0% +/- 11.2% (95% limits of agreement: -18.4% to 26.4%). The mean serum lactate from the nonfemoral and femoral CVCs was 2.84 +/- 4.0 and 2.72 +/- 3.2, respectively (P = .15).
  
  
  CONCLUSIONS
  This study revealed a significant difference between paired samples of Scv(O(2)) and Sfv(O(2)). More than 50% of Scv(O(2)) and Sfv(O(2)) values diverged by > 5%. Sfv(O(2)) is not always a reliable substitute for Scv(O(2)) and should not routinely be used in protocols to help guide resuscitation.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, The George Washington University Medical Center, Washington, DC 20037, USA.
authors.forename: Danielle L
authors.initials: DL
authors.lastname: Davison
authors.forename: Lakhmir S
authors.initials: LS
authors.lastname: Chawla
authors.forename: Leelie
authors.initials: L
authors.lastname: Selassie
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Jones
authors.forename: Kayc C
authors.initials: KC
authors.lastname: McHone
authors.forename: Amy R
authors.initials: AR
authors.lastname: Vota
authors.forename: Christopher
authors.initials: C
authors.lastname: Junker
authors.forename: Sara
authors.initials: S
authors.lastname: Sateri
authors.forename: Michael G
authors.initials: MG
authors.lastname: Seneff
mesh_terms: D002407:Catheterization, Swan-Ganz; D016638:Critical Illness; D005268:Femoral Vein; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007362:Intensive Care Units; D007601:Jugular Veins; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology*; D011446:Prospective Studies; D015203:Reproducibility of Results; D013350:Subclavian Vein
chemical_list: D006454:Hemoglobins; D010100:Oxygen