The EXACT protocol: a multi-centre, single-blind, randomised, parallel-group, controlled trial to determine whether early oxygen titration improves survival to hospital discharge in adult OHCA patients.

Background: Experimental and observational research suggests hyperoxia following resuscitation from cardiac arrest is associated with neurological injury and worse clinical outcomes. This paper describes the rationale and design of the EXACT trial. EXACT aims to determine whether reducing oxygen in the acute phase of post-resuscitation care for out-of-hospital cardiac arrest (OHCA) improves survival. Methods: EXACT is a multi-centre, randomised (1: 1), single-blind, parallel trial. Presumed cardiac OHCA cases who achieve a return of spontaneous circulation will be eligible if they are comatose, with an advanced airway and have an oxygen saturation (SpO(2)) >95% on >10 L/min (or 100% oxygen). Paramedics will randomise 1416 eligible cases to receive oxygen therapy targeting an SpO(2) of 90-94% (intervention) or 98-100% (control). Study treatment will continue until admission to an intensive care unit or hospital ward. The primary outcome is survival to hospital discharge. Secondary outcomes include 12-month survival and quality of life. Results: The study has commenced in the Australian states of Victoria and South Australia, and has enrolled 167 eligible cases to date (80 intervention and 87 control). Further sites are due to commence in 2019, recruitment is expected to take three years. Conclusion: This study will determine if early reduction of oxygen leads to improved outcomes in OHCA. Such a finding may potentially change clinical practice with implications on future OHCA survival outcomes.