Mild Hypercapnia or Normocapnia after Out-of-Hospital Cardiac Arrest

Authors:
  • GEGlenn Eastwood
    Glenn Eastwood
  • ANAlistair D. Nichol
    Alistair D. Nichol
  • RPRachael L. Parke
    Rachael L. Parke
  • SMShay McGuinness
    Shay McGuinness
  • NNNiklas Nielsen
    Niklas Nielsen
  • SBStephen Bernard
    Stephen Bernard
  • MSMarkus B. Skrifvars
    Markus B. Skrifvars
  • DSDion Stub
    Dion Stub
  • FTFabio S. Taccone
    Fabio S. Taccone
  • JAJohn Archer
    John Archer
  • DKDemetrios Kutsogiannis
    Demetrios Kutsogiannis
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Abstract
Guidelines recommend normocapnia for adults with coma who are resuscitated after out-of-hospital cardiac arrest. However, mild hypercapnia increases cerebral blood flow and may improve neurologic outcomes. We randomly assigned adults with coma who had been resuscitated after out-of-hospital cardiac arrest of presumed cardiac or unknown cause and admitted to the intensive care unit (ICU) in a 1:1 ratio to either 24 hours of mild hypercapnia (target partial pressure of arterial carbon dioxide [Paco2], 50 to 55 mm Hg) or normocapnia (target Paco2, 35 to 45 mm Hg). The primary outcome was a favorable neurologic outcome, defined as a score of 5 (indicating lower moderate disability) or higher, as assessed with the use of the Glasgow Outcome Scale-Extended (range, 1 [death] to 8, with higher scores indicating better neurologic outcome) at 6 months. Secondary outcomes included death within 6 months. A total of 1700 patients from 63 ICUs in 17 countries were recruited, with 847 patients assigned to targeted mild hypercapnia and 853 to targeted normocapnia. A favorable neurologic outcome at 6 months occurred in 332 of 764 patients (43.5%) in the mild hypercapnia group and in 350 of 784 (44.6%) in the normocapnia group (relative risk, 0.98; 95% confidence interval [CI], 0.87 to 1.11; P = 0.76). Death within 6 months after randomization occurred in 393 of 816 patients (48.2%) in the mild hypercapnia group and in 382 of 832 (45.9%) in the normocapnia group (relative risk, 1.05; 95% CI, 0.94 to 1.16). The incidence of adverse events did not differ significantly between groups. In patients with coma who were resuscitated after out-of-hospital cardiac arrest, targeted mild hypercapnia did not lead to better neurologic outcomes at 6 months than targeted normocapnia. (Funded by the National Health and Medical Research Council of Australia and others; TAME ClinicalTrials.gov number, NCT03114033.).
Funding Information
  • Health Research Council of New Zealand (19/340)
  • National Health and Medical Research Council (APP1119855)
  • Health Research Board (DIFA-2017-036)

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