The oxygen value you cite of 79% show a significant drop in your night-time blood oxygen levels. But, before you agree to the use oxygen while sleeping, you and your doctor should have additional information. Specifically, you will want to know how often and for what length of time your oxygen level was so low. Determination of the therapeutic need for oxygen with sleep should, for example, not be based on one transient fall in oxygen saturation but there should be a pattern of sustained low oxygen levels.
Your oxygen level should be 88% or higher most of the time that you are asleep.
Standards are lacking for the interpretation of night-time oximetry. For this reason it is most important that any decision about the need/use of oxygen while you sleep be made by you and your doctor, after careful assessment of the nocturnal oximetry data and your clinical status.
Yes, if you drop below 88%, you definitely need oxygen at night. Medicare will pay for it if you only drop below that for a few minutes continuously. If Lincare did an overnight oximetry on you with those results, then they will be contacting your physician to let them know. You might need O2 during the day as well. Ask your pulmonologist.