Randomisation
The study was a randomised, controlled, parallel
group trial with two arms: paramedics in the active
arm administered titrated oxygen treatment and
those in the control arm administered conventional
high flow oxygen treatment. We invited paramedics
from the Tasmanian Ambulance Service to participate
in the study and used cluster randomisation to assign
them to one of the treatment groups. We used computerised random number generation after stratification
by rurality, to reduce differences associated with transportation time between urban and rural areas. This
procedure ensured that treatment allocation was concealed before randomisation. Neither paramedics nor
the research team were blinded to treatment after randomisation. In situations in which multiple paramedics
attended a patient and had been allocated to different
study arms, the paramedic responsible for treatment
was to deliver oxygen according to his or her treatment
allocation. We informed nursing and medical staff at
the emergency department of Royal Hobart Hospital
about the trial and asked them to take an arterial blood
gas sample from each patient immediately on arrival.
We asked paramedics to inform hospital staff on arrival
that a patient was enrolled in the study and to request
the same ongoing oxygen treatment until an arterial
blood gas sample had been taken. Hospital staff were
thus not blinded to the treatment allocation. The ethics
committee waived patients’ consent, for pragmatic reasons in an acute emergency situation and because high
flow oxygen treatment was the default standard practice in the Tasmanian Ambulance Service when
the study started. To avoid contamination across treatment groups, we chose paramedics rather than patients
as the unit of randomisation