@hellopam - Sorry to hear that you are going thru the same things I did . I tried to use one and I tried too long . I think it did do me harm, the pulmonologist talked to me about it . He said it is very important to not let oxygen level go below 88. Even when I shower and change clothes , I could turn my concentrator up to 5 or 6 ltrs briefly. My consentrator only goes to 5. Even though I can get my oxygen back up to at least 92 in 1 1/2 minutes . He says every moment below 88 harms my body and brain . He said those minutes all add up . So , even though I still drop to 82 or so . I make sure I get all of the oxygen I need to walk, shop, or just go out .for a bit . If the Pom doesn’t let you move around , and keep your oxy up , then it is harming you . I am said to have stage 4 and I do use 4 liters . Since I put the Pom down and got my tanks, I do so much better . I don’t get sob . I have a rack of 24 tanks. Apria comes by once a month and swaps the empty ones . I will probably use less . It is the beginning of the snow season here . I don’t go out much in the freezing weather . I live out in the woods. It is beautiful to look at , but too cold for this old crone . 💜💜Blessed Be, Crystalina