I have COPD and have been taking Spiriva for several years, but I ran out in December, and my new shipment hasn't arrived yet . (It's Jan. 21 now) I really haven't noticed any difference without the Spiriva. Since Spiriva is VERY expensive, now I'm wondering if I really need it. My oxygen readings are normally in the 90's%, with an occasional 89%, without the Spiriva. I just took an Oxygen reading and it was 94%. It's often 95% and 96%. Do I really need to take it, or am I just making the manufacturer rich? Thank you.