Log in to MyACC
Oxygen Targets in Comatose Survivors of Cardiac Arrest
Quick Takes
- A restrictive oxygenation target of 68-75 mm Hg compared with a liberal oxygenation target of 98-105 mm Hg in comatose patients who had been resuscitated after out-of-hospital cardiac arrest showed no significant difference in the composite outcome of death or survival with a poor neurologic outcome.
- The potential pathophysiological link between brain injury and oxygenation seems to occur in the early period after cardiac arrest and to be driven by reperfusion injury with mitochondrial dysfunction and tissue inflammation, but no significant between-group difference in the primary outcome was seen in this study.
Study Questions:
What is the appropriate oxygenation target for mechanical ventilation in comatose survivors of out-of-hospital cardiac arrest?
Methods:
The BOX (Blood Pressure and OXygenation Targets After OHCA) trial investigators randomly assigned comatose adults with out-of-hospital cardiac arrest in a 1:1 ratio to either a restrictive oxygen target of a partial pressure of arterial oxygen (Pao2) of 9-10 kPa (68-75 mm Hg) or a liberal oxygen target of a Pao2 of 13-14 kPa (98-105 mm Hg) in this randomized trial with a 2-by-2 factorial design. The primary outcome was a composite of death from any cause or hospital discharge with severe disability or coma (Cerebral Performance Category [CPC] of 3 or 4; categories range from 1-5, with higher values indicating more severe disability), whichever occurred first within 90 days after randomization. Secondary outcomes were neuron-specific enolase levels at 48 hours, death from any cause, the score on the Montreal Cognitive Assessment (ranging from 0-30, with higher scores indicating better cognitive ability), the score on the modified Rankin scale (ranging from 0-6, with higher scores indicating greater disability), and the CPC at 90 days. The authors performed Cox proportional-hazards analysis with adjustment for trial site to calculate the hazard ratio and 95% confidence interval (CI) for the primary composite outcome in the oxygenation intervention.
Results:
A total of 789 patients underwent randomization. A primary outcome event occurred in 126 of 394 patients (32.0%) in the restrictive-target group and in 134 of 395 patients (33.9%) in the liberal-target group (hazard ratio, 0.95; 95% CI, 0.75-1.21; p = 0.69). At 90 days, death had occurred in 113 patients (28.7%) in the restrictive-target group and in 123 (31.1%) in the liberal-target group. On the CPC, the median category was 1 in the two groups; on the modified Rankin scale, the median score was 2 in the restrictive-target group and 1 in the liberal-target group; and on the Montreal Cognitive Assessment, the median score was 27 in the two groups. At 48 hours, the median neuron-specific enolase level was 17 μg/L in the restrictive-target group and 18 μg/L in the liberal-target group. The incidence of adverse events was similar in the two groups.
Conclusions:
The authors concluded that a restrictive or liberal oxygenation strategy in comatose patients after resuscitation for cardiac arrest resulted in a similar incidence of death or severe disability or coma.
Perspective:
This randomized trial compared a restrictive oxygenation target of 68-75 mm Hg with a liberal oxygenation target of 98-105 mm Hg in comatose patients who had been resuscitated after out-of-hospital cardiac arrest and found no significant difference between liberal and restrictive oxygenation targets in the composite outcome of death or survival with a poor neurologic outcome. Furthermore, the results were consistent in all prespecified subgroups. The potential pathophysiological link between brain injury and oxygenation seems to occur in the early period after cardiac arrest and to be driven by reperfusion injury with mitochondrial dysfunction and tissue inflammation, but no significant between-group difference in the primary outcome was seen in this open-label study.
Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Cardiovascular Care Team, Prevention, Vascular Medicine, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias
Keywords: Acute Coronary Syndrome, Arrhythmias, Cardiac, Blood Pressure, Brain Injuries, Cognition, Coma, Heart Arrest, Inflammation, Mental Status and Dementia Tests, Mitochondria, Out-of-Hospital Cardiac Arrest, Oxygen, Partial Pressure, Patient Discharge, Reperfusion Injury, Respiration, Artificial, Secondary Prevention, Survivors, Ventilation
< Back to Listings
