ผRandomization and Masking
Computer-generated block randomization was performed, with ambulances carrying opaque
envelopes numbered externally, concealing treatment assignment. Individuals involved with the
delivery of oxygen therapy pre-hospital and in-hospital were not blinded to treatment
assignment. Six month follow up of all patients was performed by a central coordinator blinded
to treatment assignment. Investigators undertaking data analysis were masked to treatment
assignment for primary endpoints and six-month telephone follow-up.
Procedures
In the oxygen group patients were administered supplemental oxygen via face mask at 8 L/min
by paramedics, and this therapy continued until transfer from the cardiac catheterization
laboratory to the cardiac care ward. Patients randomized to the no oxygen arm received no
oxygen unless oxygen saturation fell below 94% in which case oxygen was administered via
nasal cannula (4 L/min) or face mask (8 L/min) to achieve an oxygen saturation of 94%. All