My husband had severe copd, he was put on an oxygen concentrater 1lpm for 15hrs a day, after about 6-7 months he ended up in hospital, unconscious, he nearly died, he was told he was a Co2 retainer and could only have short bursts of oxygen when necessary. Just before Christmas he got pneumonia and had to go into hospital on a cpap or dpap machine, which made him feel very claustrophobic. After two days he wanted a rest from the mask and refused to put it on, so the nurse put him on oxygen and turned it right up to either 8 litres or 15 litres, he was dead the next morning, even though he'd been doing really well, he was a very young 62.