Background There is evidence that systematic cardiac arrest care after return of spontaneous circulation (ROSC) improves chances of survival with a good quality of life. Post cardiac arrest care is a critical component of advanced life support. It is postulated that exposing ischaemic brain tissue to significant hyperoxaemia during this period increases the possibility of oxidative injury and cellular death.

This study was designed to demonstrate the feasibility of completing a cluster-randomised clinical trial to determine if oxygen therapy titrated to oxygen saturation as measured by a pulse oximeter (target SpO₂ 94–98%) for 1 hour after a sustained return of spontaneous circulation (ROSC) is superior in improving outcome following non traumatic out of hospital cardiac arrest (OHCA) in adults, compared with the use of non-titrated, 100% oxygen.

Methods Paramedics were randomly allocated to one of two trial arms (100% oxygen or titrated oxygen to a target SpO₂ of 94–98%). The intervention was initiated in adult non-traumatic OHCA once the patient achieved a sustained (>2 minutes) ROSC. Interventions were either the administration of 100% oxygen or oxygen titrated to a target SpO₂ of 94–98% for 60 minutes, continued in the receiving Emergency Department if necessary.

Results In the intervention arm of the study, paramedics were able to titrate the inspired oxygen concentration in 72% of patients and obtain a reliable reading of oxygen saturation immediately after ROSC in 61% of patients.

The assigned oxygen therapy was continued for 60 minutes after ROSC in 74% of patients for whom the intervention was initiated. Legitimate reasons for discontinuation (e.g. death) occurred in a further 11%.

Conclusion This study indicates that a future full scale trial to determine if titrated oxygen therapy is superior to 100% oxygen in improving patient outcome after non traumatic OHCA is feasible.