Narrative:

The passenger was an elderly lady who pre-boarded the aircraft because I helped attach her portable oxygen concentrator (which was approved) to the bar underneath her seat. Other than her age and the concentrator; nothing was apparent for the majority of the flight that would suggest she was unhealthy in any other way or unable to fly. When there was approximately one and a half hours left of the three hour flight she started to fan herself with the safety demo card. I recognized this and asked her what the matter was. She told me she was just hot. I first made sure her gasper vent was opened all the way and then I lowered the cabin temperature; I also asked if there was anything else I could do for her. She said no. Her companion was testing her oxygen levels with a pulse oximeter. They told me that her oxygen levels were a little lower than normal (at about 90). I asked if there was anything I could do and they told me that they wanted to wait just a few minutes to see if the levels would start to rise again. I informed the other flight attendant; of the situation after I talked to the pilots over the interphone. I also told them that if her oxygen level dropped anymore; we would use the oxygen on the aircraft for her. One of the times I checked her oxygen level had dropped to 88; a little below normal. At this time; I went to the back to inform the other flight attendant and called the pilots to tell them we would be using the oxygen on her. I got the forward oxygen out of the latch and brought it to her seat. I turned the knob on the bottle to start the flow of oxygen and both the other flight attendant and I tried to turn the red bayonet fitting to stop the oxygen from flowing into that tube. Neither of us could get it. We put the oxygen mask attached to the blue fitting over the passenger's head and tightened it. We told her we would still continue to check in on her. We checked her oxygen levels on the pulse oximeter again and it gained back to about 99 at this time (and for the remainder of the flight). At this time; there was approximately 40 minutes left of flight. I returned the galley area and checked in the fam on what it said to do to stop the flow of the flight attendant bayonet fitting and tube. It reads; 'disconnect the bayonet fitting of mask not in use to preserve oxygen.' I went back and tried again to detach the fitting; but was unsuccessful. I called the captain; to tell him what was happening and ask if he or the first officer could come out and try to disconnect the fitting because the other flight attendant and I couldn't get it. After explaining to him that we both thought we were supposed to turn the fitting to disconnect it and were unable to; he said he thought it would be ok if we just left it as is; considering there was only about 35 minutes left in flight and he didn't know how to disconnect it either.we soon got the 'prepare for arrival' briefing from the flight deck and had started our descent. We did our usual jobs preparing for arrival; cleaning up; and compliance checks as we made it to 10;000 ft and sterile cockpit. When I was cleaning up glasses and such in first class; I again checked to see how she was doing and her condition was stable; her oxygen levels were maintained around 98 or so. I checked the bottle meter and it had only dropped approximately 300 or 400 psi below its full state. We soon took our seats for landing. I approached them and helped detach the bottle from the bar at the bottom of her seat and her companion had already detached her concentrator. She walked off the plane and to the wheelchair; which was; by this time; waiting for her. It wasn't until now; when we were looking at the oxygen bottle; that we realized it was depleted and empty. Since the duration of the bottle is supposed to be approximately 1 hour and 15 minutes; neither of us thought this would happen. The captain came and looked at it himself as well and we all came to the conclusion that this must have occurred because both tubes were still connected and the oxygen was flowing at not just the normal four liters/minute for the passenger or even eight liters/minute for flight attendant; but at twelve liters/minute. Maybe somewhere in the fam put how to disconnect the bayonet fitting.

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Original NASA ASRS Text

Title: An EMB175 Flight Attendant was using a portable oxygen bottle for an elderly passenger. Neither Flight Attendant in the cabin was able to figure out how to disconnect or stop the oxygen flow to the Flight Attendant mask which was also connected to the bottle. The bottle was empty after landing.

Narrative: The passenger was an elderly lady who pre-boarded the aircraft because I helped attach her portable oxygen concentrator (which was approved) to the bar underneath her seat. Other than her age and the concentrator; nothing was apparent for the majority of the flight that would suggest she was unhealthy in any other way or unable to fly. When there was approximately one and a half hours left of the three hour flight she started to fan herself with the safety demo card. I recognized this and asked her what the matter was. She told me she was just hot. I first made sure her gasper vent was opened all the way and then I lowered the cabin temperature; I also asked if there was anything else I could do for her. She said no. Her companion was testing her oxygen levels with a pulse oximeter. They told me that her oxygen levels were a little lower than normal (at about 90). I asked if there was anything I could do and they told me that they wanted to wait just a few minutes to see if the levels would start to rise again. I informed the other flight attendant; of the situation after I talked to the pilots over the interphone. I also told them that if her oxygen level dropped anymore; we would use the oxygen on the aircraft for her. One of the times I checked her oxygen level had dropped to 88; a little below normal. At this time; I went to the back to inform the other Flight Attendant and called the pilots to tell them we would be using the oxygen on her. I got the forward oxygen out of the latch and brought it to her seat. I turned the knob on the bottle to start the flow of oxygen and both the other Flight Attendant and I tried to turn the red bayonet fitting to stop the oxygen from flowing into that tube. Neither of us could get it. We put the oxygen mask attached to the blue fitting over the passenger's head and tightened it. We told her we would still continue to check in on her. We checked her oxygen levels on the pulse oximeter again and it gained back to about 99 at this time (and for the remainder of the flight). At this time; there was approximately 40 minutes left of flight. I returned the galley area and checked in the FAM on what it said to do to stop the flow of the flight attendant bayonet fitting and tube. It reads; 'Disconnect the bayonet fitting of mask not in use to preserve oxygen.' I went back and tried again to detach the fitting; but was unsuccessful. I called the Captain; to tell him what was happening and ask if he or the First Officer could come out and try to disconnect the fitting because the other Flight Attendant and I couldn't get it. After explaining to him that we both thought we were supposed to turn the fitting to disconnect it and were unable to; he said he thought it would be ok if we just left it as is; considering there was only about 35 minutes left in flight and he didn't know how to disconnect it either.We soon got the 'prepare for arrival' briefing from the flight deck and had started our descent. We did our usual jobs preparing for arrival; cleaning up; and compliance checks as we made it to 10;000 FT and sterile cockpit. When I was cleaning up glasses and such in First Class; I again checked to see how she was doing and her condition was stable; her oxygen levels were maintained around 98 or so. I checked the bottle meter and it had only dropped approximately 300 or 400 PSI below its full state. We soon took our seats for landing. I approached them and helped detach the bottle from the bar at the bottom of her seat and her companion had already detached her concentrator. She walked off the plane and to the wheelchair; which was; by this time; waiting for her. It wasn't until now; when we were looking at the oxygen bottle; that we realized it was depleted and empty. Since the duration of the bottle is supposed to be approximately 1 hour and 15 minutes; neither of us thought this would happen. The Captain came and looked at it himself as well and we all came to the conclusion that this must have occurred because both tubes were still connected and the oxygen was flowing at not just the normal four liters/minute for the passenger or even eight liters/minute for flight attendant; but at twelve liters/minute. Maybe somewhere in the FAM put how to disconnect the bayonet fitting.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.