title: Central and mixed venous oxygen saturation in septic shock: is there a clinically relevant difference?
abstract: BACKGROUND
  Central venous oxygen saturation (SvcO2) has been proposed as an alternative for mixed venous oxygen saturation (SvO2), with a variable level of acceptance according to available data. This study aimed to evaluate possible differences between SvO2 and SvcO2 or atrial venous saturation (SvaO2), with emphasis on the role of cardiac output and their impact on clinical management of the septic patient.
  
  
  METHODS
  This is an observational, prospective study of patients with septic shock monitored by pulmonary artery catheter. Blood was obtained simultaneously for SvcO2, SvO2 and SvaO2 determination. Linear correlation (significant if p<0.05) and agreement analysis (Bland-Altman) were performed with samples and subgroups according to cardiac output. Moreover, agreement about clinical management based on these samples was evaluated.
  
  
  RESULTS
  Sixty one measurements from 23 patients were obtained, median age of 65.0 (49.0-75.0) years and mean APACHE II of 27.7±6.3. Mean values of SvO2, SvcO2 and SvaO2 were 72.20±8.26%, 74.61±7.60% and 74.64±8.47%. Linear correlation test showed a weak correlation between SvO2 and SvcO2 (r=0.61, p<0.0001) and also between SvO2 and SvaO2 (r=0.70, p<0.0001). Agreements between SvcO2/SvO2 and SvaO2/SvO2 were -2.40±1.96 (-16.20 and 11.40) and -2.40±1.96 (-15.10 and 10.20), respectively, with no difference in the cardiac output subgroups. No agreement was found in clinical management for 27.8% of the cases, both for SvcO2/SvO2 and for SvaO2/SvO2.
  
  
  CONCLUSIONS
  This study showed that the correlation and agreement between SvO2 and SvcO2 is weak and may lead to different clinical management.
authors.affiliation: Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Flavia Ribeiro
authors.initials: FR
authors.lastname: Machado
authors.affiliation: Setor de Terapia Intensiva da Disciplina de Anestesiologia, Dor e Terapia Intensiva, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Rosana Borges de
authors.initials: RB
authors.lastname: Carvalho
authors.affiliation: Setor de Terapia Intensiva da Disciplina de Anestesiologia, Dor e Terapia Intensiva, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Flávio Geraldo Rezende
authors.initials: FG
authors.lastname: Freitas
authors.affiliation: Setor de Terapia Intensiva da Disciplina de Anestesiologia, Dor e Terapia Intensiva, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Luciana Coelho
authors.initials: LC
authors.lastname: Sanches
authors.affiliation: Setor de Terapia Intensiva da Disciplina de Anestesiologia, Dor e Terapia Intensiva, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Miriam
authors.initials: M
authors.lastname: Jackiu
authors.affiliation: Setor de Terapia Intensiva da Disciplina de Anestesiologia, Dor e Terapia Intensiva, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Bruno Franco
authors.initials: BF
authors.lastname: Mazza
authors.affiliation: Setor de Terapia Intensiva da Disciplina de Anestesiologia, Dor e Terapia Intensiva, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Murillo
authors.initials: M
authors.lastname: Assunção
authors.affiliation: Setor de Terapia Intensiva da Disciplina de Anestesiologia, Dor e Terapia Intensiva, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Helio Penna
authors.initials: HP
authors.lastname: Guimarães
authors.affiliation: Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Jose Luiz Gomes do
authors.initials: JL
authors.lastname: Amaral