germain - I don't work LTC, but I do work with a lot of vent patients in the hospital. I've also worked in home care with kids on long term vent support. I would have to say YES!!
Ideally, these patients should be out of bed daily. Whether into a wheel chair or some kind of geri chair at the bedside.
Realistically though, it is a lot of work to do that for a large number of patients - and may not be possible at the place where you work. The kids I worked with had vents on their w/cs, but obviously this is probably not possible for patients in a nursing home. Unless they have portable vents, it would be impossible to get them outside unless someone bagged them the whole time. Sounds like a very sad situation - no family visiting? I don't know what else to tell you, except wait for someone on this board to respond who has some experience with this type of unit.
Good luck, you sound like a very compassionate person