Most patients with suspected acute coronary syndrome (ACS) don’t have better 30-day mortality outcomes when they receive high-flow oxygen, researchers say.

In the trial conducted in New Zealand 40,872 patients with suspected or confirmed ACS episodes were randomised either to receive high-flow oxygen irrespective of SpO₂  (6-8L/min by face mask or 4L/min by nasal cannula) or to a low-flow oxygen protocol.

In the low-flow protocol, oxygen was recommended only for patients with ischaemic chest pain or dyspnoea with electrocardiographic changes if SpO₂ was less than 90%, and the flow rate was adjusted to maintain SpO₂ between 90% and 94%. 

Looking at the results for all participants, mortality over the next 30 days was similar with high-flow oxygen (3.0%) and low-flow oxygen (3.1%).