SpO2 Anomaly

My lung volume is about 50% of expected for my age.  Before meds, resting SpO2 was base 88-89, mild exertion 82% or so.  Now with Singulair, Salmeterol, Flovent and Albuterol perfusion has increased (in general) about 5 points.  Anomaly is when I am shortest of breath O2 perfusion measurement is generally about 91 - 95%.  These numbers were unheard of before use of meds.  My physician is at a loss to explain.  Cardiologist says I am in good shape, just 1 week ago.  However I still have great difficulty breathing regardless of SpO2 and use O2 (2L/min) often at home as well when sleeping (ON CPAP).  Any opinions as to this anomaly?

Thanks, Bob

[National Jewish]

It is a possibility that the medications have altered the process for exchanging oxygen and carbon dioxide in your lungs. More oxygen may be delivered to the blood and this is why your oxygen saturation level is normal. However, there could still be some obstruction in your airways, causing you to work harder to breathe and this can lead to shortness of breath. Many people with chronic lung disease experience shortness of breath with a normal oxygen saturation.