title: Central venous-arterial pCO₂ difference as a tool in resuscitation of septic patients.
abstract: OBJECTIVE
  To investigate the interchangeability of mixed and central venous-arterial carbon dioxide differences and the relation between the central difference (pCO₂ gap) and cardiac index (CI). We also investigated the value of the pCO₂ gap in outcome prediction.
  
  
  METHODS
  We performed a post hoc analysis of a well-defined population of 53 patients with severe sepsis or septic shock. Mixed and central venous pCO₂ were determined earlier at a 6 h interval (T = 0 to T = 4) during the first 24 h after intensive care unit (ICU) admittance. The population was divided into two groups based on pCO₂ gap (cut off value 0.8 kPa).
  
  
  RESULTS
  The mixed pCO₂ difference underestimated the central pCO₂ difference by a mean bias of 0.03 ± 0.32 kPa (95 % limits of agreement: -0.62-0.58 kPa). We observed a weak relation between pCO₂ gap and CI. The in hospital mortality rate was 21 % (6/29) for the low gap group and 29 % (7/24) for the high gap group; the odds ratio was 1.6 (95 % CI 0.5-5.5), p = 0.53. At T = 4 the odds ratio was 5.3 (95 % CI 0.9-30.7); p = 0.08.
  
  
  CONCLUSIONS
  From a practical perspective, the clinical utility of central venous pCO₂ values is of potential interest in determining the venous-arterial pCO₂ difference. The likelihood of a bad outcome seems to be enhanced when a high pCO₂ gap persists after 24 h of therapy.
authors.affiliation: Department of Anesthesiology, University Medical Center Groningen, University of Groningen, 30001, 9700 RB Groningen, The Netherlands. p.van.beest@umcg.nl
authors.forename: Paul A
authors.initials: PA
authors.lastname: van Beest
authors.forename: Mariska C
authors.initials: MC
authors.lastname: Lont
authors.forename: Nicole D
authors.initials: ND
authors.lastname: Holman
authors.forename: Bert
authors.initials: B
authors.lastname: Loef
authors.forename: Michaël A
authors.initials: MA
authors.lastname: Kuiper
authors.forename: E Christiaan
authors.initials: EC
authors.lastname: Boerma
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D011237:Predictive Value of Tests; D012151:Resuscitation / Q000379:methods*; D018805:Sepsis / Q000097:blood / Q000401:mortality / Q000628:therapy*; D012772:Shock, Septic / Q000097:blood / Q000628:therapy
chemical_list: D002245:Carbon Dioxide
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