To clear up any confusion, there will be no decisions made on which patients are given ABL and which are not. I'm sure consecutive patients with the selection criteria and without exclusion criteria will be assigned to one or the other based on a randomisation schedule created before the trial starts.

Open label trials are quicker to set up, but any trial that is unblinded is susceptiple to bias for clinical endpoints (eg, the decision of when to transfer a patient out of the ICU) and the results of investigations (eg, reading chest radiographs, perhaps reading a piece of lab equipment that measures blood oxygen), even if this is subconscious and involuntary. So I'm sure the FDA will want a blinded trial if the first one looks good. I think it's unavoidable.