pegtube

My father was recently diagnosed with bulbar onset ALS in April. He had been to many different doctors with misdiagnosis's along the way. At this point his swallowing is almost non-existent. He goes back and forth about a feeding tube but he is so far along that his lung functioning is at 48%. I am worried about him having trouble in the operating room. My questions are:
1. At what point is it considered unsafe to place the peg tube with comprimised lung functions?
2. Is it normal to go back and forth with the decision even tho he has lost well over 100 lbs.