I'd descend to 310 for a start,once I.d established that there was no O2 in the tank(try the mask)..Call for a supplemental first aid bottle to the cockpit,consider a diversion if the 310 fuel inadequate..The TUC at 310 would be sufficient to do the descent and share the bottle...Your turn
cheers
I\'m not sure the QRH would cover the lack/loss of Crew O2,
but should cover depressurized flight dispatch limits..
