Could Severe Itching In Body Be Due To Reduced Oxygen Levels?

my mother is 94 years old and has had conjestive heart failure for the last 12 years,recently ,this past sept she had a strke that semi paralized the right side of her body.since she had her stroke her medications have been added to and some changed.Recently I purchased a apparatus that monitors her oxygen level and heart rate, using this I noticed that while she was home her oxygen level would drop to 84 so in I take her to the hospital to see if we can retreive a oxygen machine.So she has oxygen now and we keep her rate at 97 for her oxygen ,her heart runs at 64.Lateley she has been itching like crazy ,scratching and digging in a wild ferenzie.Is it her medications or her oxygen ,making her itch?Here are here perscriptions,bisoprol fumarate 5 mg,pantoprazole magn ec40mg,apo furosemide 40mg,sadoz amlodipine 5mgand warfarin 2.5mg