title: Arterial carbon dioxide tension and outcome in patients admitted to the intensive care unit after cardiac arrest.
abstract: BACKGROUND
  Arterial carbon dioxide tension (PaCO2) affects neuronal function and cerebral blood flow. However, its association with outcome in patients admitted to intensive care unit (ICU) after cardiac arrest (CA) has not been evaluated.
  
  
  RESULTS
  Observational cohort study using data from the Australian New Zealand (ANZ) Intensive Care Society Adult-Patient-Database (ANZICS-APD). Outcomes analyses were adjusted for illness severity, co-morbidities, hypothermia, treatment limitations, age, year of admission, glucose, source of admission, PaO2 and propensity score. We studied 16,542 consecutive patients admitted to 125 ANZ ICUs after CA between 2000 and 2011. Using the APD-PaCO2 (obtained within 24 h of ICU admission), 3010 (18.2%) were classified into the hypo- (PaCO2<35 mmHg), 6705 (40.5%) into the normo- (35-45 mmHg) and 6827 (41.3%) into the hypercapnia (>45 mmHg) group. The hypocapnia group, compared with the normocapnia group, had a trend toward higher in-hospital mortality (OR 1.12 [95% CI 1.00-1.24, p=0.04]), lower rate of discharge home (OR 0.81 [0.70-0.94, p<0.01]) and higher likelihood of fulfilling composite adverse outcome of death and no discharge home (OR 1.23 [1.10-1.37, p<0.001]). In contrast, the hypercapnia group had similar in-hospital mortality (OR 1.06 [0.97-1.15, p=0.19]) but higher rate of discharge home among survivors (OR 1.16 [1.03-1.32, p=0.01]) and similar likelihood of fulfilling the composite outcome (OR 0.97 [0.89-1.06, p=0.52]). Cox-proportional hazards modelling supported these findings.
  
  
  CONCLUSIONS
  Hypo- and hypercapnia are common after ICU admission post-CA. Compared with normocapnia, hypocapnia was independently associated with worse clinical outcomes and hypercapnia a greater likelihood of discharge home among survivors.
authors: Department of Intensive Care, Austin Hospital, Melbourne, Victoria, Australia.
authors: Antoine G
authors: AG
authors: Schneider
authors: Glenn M
authors: GM
authors: Eastwood
authors: Rinaldo
authors: R
authors: Bellomo
authors: Michael
authors: M
authors: Bailey
authors: Miklos
authors: M
authors: Lipcsey
authors: David
authors: D
authors: Pilcher
authors: Paul
authors: P
authors: Young
authors: Peter
authors: P
authors: Stow
authors: John
authors: J
authors: Santamaria
authors: Edward
authors: E
authors: Stachowski
authors: Satoshi
authors: S
authors: Suzuki
authors: Nicholas C
authors: NC
authors: Woinarski
authors: Janine
authors: J
authors: Pilcher
mesh_terms: D002245:Carbon Dioxide / Q000097:blood*; D015331:Cohort Studies; D016208:Databases, Factual; D005260:Female; D006323:Heart Arrest / Q000097:blood* / Q000401:mortality*; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D010351:Patient Discharge; D063868:Patient Outcome Assessment; D016016:Proportional Hazards Models
chemical_list: D002245:Carbon Dioxide