Lay summary
In animal models, exposure to high levels of oxygen after cardiac arrest worsens brain injury.Despite this, standard care of patients after cardiac arrest includes exposure to abnormally high levels of oxygen for prolonged periods.Our full study will establish whether limiting exposure to high levels of oxygen following cardiac arrest improves neurological outcomes.In this current multicentre RCT, 42 patients resuscitated from community cardiac arrest will receive either standard therapy or careful titration of oxygen to avoid either abnormally high or low oxygen levels.This study will determine whether patients can be effectively randomised into a study with the design of the proposed full study and whether separation of oxygen exposure between study groups can be achieved.If careful titration of oxygen is ultimately shown to reduce brain injury after cardiac arrest, this finding will have a major impact on the management of cardiac arrest in New Zealand and internationally.