In comatose patients resuscitated from an out-of-hospital cardiac arrest, targeting of a restrictive or liberal oxygenation strategy resulted in a similar incidence of death or severe disability or coma, based on findings from the BOX trial presented Aug. 27 during ESC Congress 2022 in Barcelona, and simultaneously published in the New England Journal of Medicine.

Researchers randomly assigned 789 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 to 10 kPa (68 to 75 mmHg) or a liberal oxygen target of a Pao2 of 13 to 14 kPa (98 to 105 mmHg). The primary outcome was a composite of death from any cause or hospital discharge with severe disability or coma, whichever occurred first within 90 days after randomization. Secondary outcomes included neuron-specific enolase levels at 48 hours, death from any cause, scores on the Montreal Cognitive Assessment and the modified Rankin scale, and Cerebral Performance Category at 90 days.

Overall, researchers reported a primary-outcome event occurred in 126 of the 394 patients (32.0%) in the restrictive-target group compared with 134 of 395 patients (33.9%) in the liberal-target. At 90 days, death had occurred in 113 patients (28.7%) in the restrictive-target group and in 123 patients (31.1%) in the liberal-target group. The incidence of adverse events was similar in the two groups.

"The present study demonstrates no benefit of aiming for at higher oxygen target in post out of hospital cardiac arrest care," said Jacob Eifer Møller, MD, DMSc, who presented the findings. He added that the study also "reassures that a restrictive oxygen target for patients with high risk of hypoxic brain injury cause no harm."

In addition to being assigned to restrictive or liberal oxygen targets, BOX patients were also assigned to one of two blood-pressure targets. These findings, which were presented separately and simultaneously published in the New England Journal of Medicine, found no benefit in targeting a mean arterial blood pressure of 77 mmHg vs. 63 mmHg as part of post-cardiac arrest care. "Targeting a high blood pressure in the ICU following cardiac arrest does not translate in lower risk of death or severe disability," said Møller.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, SCD/Ventricular Arrhythmias, Heart Failure and Cardiac Biomarkers

Keywords: ESC Congress, ESC22, ACC International, Out-of-Hospital Cardiac Arrest, Arterial Pressure, Intensive Care Units, Brain Injuries, Oxygen, Phosphopyruvate Hydratase

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