Target O2 saturation of 90-94% fails to improve survival in out-of-hospital Cardiac Arrest resuscitation

The EXACT randomized trial found that patients having an out-of-hospital cardiac arrest and achieving the return of spontaneous circulation with an oxygen saturation of 90% to 94% did not have an improved survival rate when compared with 98% to 100% oxygen saturation until admission to the intensive care unit. The trial results were published in the journal JAMA Network.  

In out-of-hospital cardiac arrest, the administration of a high oxygen concentration following spontaneous circulation recovery may increase reperfusion brain injury. Researchers conducted a trial to determine whether targeting a lower oxygen saturation in the early phase of post-resuscitation care for out-of-hospital cardiac arrest improves survival at hospital discharge. 

Between December 11, 2017, and August 11, 2020, a multicenter, parallel-group randomized clinical trial was done on unconscious adults with the return of spontaneous circulation and peripheral oxygen saturation (Spo2) of at least 95% while receiving 100% oxygen at 2 emergency medical services and 15 hospitals in Victoria and South Australia, Australia. Data was collected from ambulance and hospital medical records. 428 patients enrolled in the trial were randomized by paramedics to two groups of Intervention group with 216 patients and a standard care group with 212 patients. They received oxygen titration to achieve an oxygen saturation of either 90% to 94% in the intervention group or 98% to 100% in the standard care group until arrival in the intensive care unit. The primary outcome was survival until discharge from the hospital. Hypoxic episodes (Spo2 90%) and prespecified serious adverse events, such as hypoxia with rearrest, were among the nine secondary outcomes gathered.

Results:

• Of the 428 randomized patients, 425 were included in the primary analysis with median age, of 65.5 years and 100 [23.5%] females and all completed the trial. 
• Overall, 82 of 214 patients (38.3%) in the intervention group survived hospital discharge compared with 101 of 211 (47.9%) in the standard care group (difference, −9.6%).
• 8 showed no significant difference, between the 9 prespecified secondary outcomes collected during a hospital stay.
• 31.3% (n = 67) of participants in the intervention group and 16.1% (n = 34) in the standard care group showed a hypoxic episode before intensive care. 

Though the trial was terminated early due to the COVID-19 pandemic, the trial results do not support the use of a 90% to 94% oxygen saturation target in the out-of-hospital setting after resuscitation from cardiac arrest. 

Further reading: Bernard SA, Bray JE, Smith K, et al. Effect of Lower vs Higher Oxygen Saturation Targets on Survival to Hospital Discharge Among Patients Resuscitated After Out-of-Hospital Cardiac Arrest: The EXACT Randomized Clinical Trial. JAMA. Published online October 26, 2022.

doi:10.1001/jama.2022.17701