title: Associations of arterial carbon dioxide and arterial oxygen concentrations with hospital mortality after resuscitation from cardiac arrest.
abstract: BACKGROUND
  Arterial concentrations of carbon dioxide (PaCO2) and oxygen (PaO2) during admission to the intensive care unit (ICU) may substantially affect organ perfusion and outcome after cardiac arrest. Our aim was to investigate the independent and synergistic effects of both parameters on hospital mortality.
  
  
  METHODS
  This was a cohort study using data from mechanically ventilated cardiac arrest patients in the Dutch National Intensive Care Evaluation (NICE) registry between 2007 and 2012. PaCO2 and PaO2 levels from arterial blood gas analyses corresponding to the worst oxygenation in the first 24 h of ICU stay were retrieved for analyses. Logistic regression analyses were performed to assess the relationship between hospital mortality and both categorized groups and a spline-based transformation of the continuous values of PaCO2 and PaO2.
  
  
  RESULTS
  In total, 5,258 cardiac arrest patients admitted to 82 ICUs in the Netherlands were included. In the first 24 h of ICU admission, hypocapnia was encountered in 22 %, and hypercapnia in 35 % of included cases. Hypoxia and hyperoxia were observed in 8 % and 3 % of the patients, respectively. Both PaCO2 and PaO2 had an independent U-shaped relationship with hospital mortality and after adjustment for confounders, hypocapnia and hypoxia were significant predictors of hospital mortality: OR 1.37 (95 % CI 1.17-1.61) and OR 1.34 (95 % CI 1.08-1.66). A synergistic effect of concurrent derangements of PaCO2 and PaO2 was not observed (P = 0.75).
  
  
  CONCLUSIONS
  The effects of aberrant arterial carbon dioxide and arterial oxygen concentrations were independently but not synergistically associated with hospital mortality after cardiac arrest.
authors.affiliation: Department of Intensive Care Medicine, Leiden University Medical Center, Post Box 9600, Leiden, 2300 RC, The Netherlands. H.J.F.Helmerhorst@lumc.nl.|Laboratory of Experimental Intensive Care and Anesthesiology, Academic Medical Center, Meibergdreef 9, Amsterdam, 1105 AZ, The Netherlands. H.J.F.Helmerhorst@lumc.nl.
authors.forename: Hendrik J F
authors.initials: HJ
authors.lastname: Helmerhorst
authors.affiliation: Department of Medical Informatics, Academic Medical Center, Meibergdreef 9, Amsterdam, 1105 AZ, The Netherlands. m.blom@amc.uva.nl.|National Intensive Care Evaluation (NICE) foundation, Meibergdreef 9, Amsterdam, 1105 AZ, The Netherlands. m.blom@amc.uva.nl.
authors.forename: Marie-José
authors.initials: MJ
authors.lastname: Roos-Blom
authors.affiliation: Department of Intensive Care Medicine, Leiden University Medical Center, Post Box 9600, Leiden, 2300 RC, The Netherlands. D.J.van_Westerloo@lumc.nl.
authors.forename: David J
authors.initials: DJ
authors.lastname: van Westerloo
authors.affiliation: Department of Medical Informatics, Academic Medical Center, Meibergdreef 9, Amsterdam, 1105 AZ, The Netherlands. a.abu-hanna@amc.uva.nl.
authors.forename: Ameen
authors.initials: A
authors.lastname: Abu-Hanna
authors.affiliation: Department of Medical Informatics, Academic Medical Center, Meibergdreef 9, Amsterdam, 1105 AZ, The Netherlands. n.f.keizer@amc.uva.nl.|National Intensive Care Evaluation (NICE) foundation, Meibergdreef 9, Amsterdam, 1105 AZ, The Netherlands. n.f.keizer@amc.uva.nl.
authors.forename: Nicolette F
authors.initials: NF
authors.lastname: de Keizer
authors.affiliation: Department of Intensive Care Medicine, Leiden University Medical Center, Post Box 9600, Leiden, 2300 RC, The Netherlands. E.de_Jonge@lumc.nl.|National Intensive Care Evaluation (NICE) foundation, Meibergdreef 9, Amsterdam, 1105 AZ, The Netherlands. E.de_Jonge@lumc.nl.
authors.forename: Evert
authors.initials: E
authors.lastname: de Jonge
mesh_terms: D000368:Aged; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006323:Heart Arrest / Q000097:blood / Q000401:mortality* / Q000628:therapy; D017052:Hospital Mortality; D006801:Humans; D006935:Hypercapnia / Q000209:etiology / Q000401:mortality; D018496:Hyperoxia / Q000209:etiology / Q000401:mortality; D016857:Hypocapnia / Q000209:etiology / Q000401:mortality; D000860:Hypoxia / Q000209:etiology / Q000401:mortality; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D012151:Resuscitation / Q000401:mortality*
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen