10LPM may indeed be enough for a pt. who is not compromised except for a malfunctioning vent, depending on what sort of a mix they were on when the vent was working.
The reference to switching to hypoxic drive and inhibiting breathing, as you may have gathered, garners signifigant skepticism at this site (and among educated providers everywhere). The notion that COPD'rs can't tolerate high flow 02 is just not supported by evidence, and basically is wrong (according to me).
That said, even if you do end up inhibiting their respiratory drive (unlikely) - if you are ventilating with a BVM: Who cares? You are their respiratory drive now. You're breathing for them.
If the COPD pt. is not breathing adequately or in resp. distress - give them high flow O2. If they are being adequately oxygenated by a vent using a room air mix, it's probably OK to withold the highest flow 02.
for more:
http://emtlife.com/showthread.php?t=4225&highlight=hypoxic+drive
Really, if I'm ventilating by BVM I'm going to crank the O2 all the way up just to make sure, COPD or not. Even a transport time of an hour isn't going to have any major impact, and it's much worse to find out you were ventilating insufficiently.