low lung volumes

I am a 47 year old female who had been investigated several times for pulmonary hypertension as I have an elevated pressure on echo(51). right heart catheterization is normal though. I remain quite short of breath on exertion and have a chronic cough. On my last pft's the only abnormality was a low residual volume of 1.09 which was 69% predicted. The report said this could be explained by normal age decline. I googled it and all I found was that the lung volumes should increase with age! All my lung volume measurements were lower than a year ago. Anyone know anything about this?

[Resilient_Mimi]

Residual Volume is the amount of air left in the lungs even when we try to blow it all out. Low volume can be from Asthma to Emphysema. Height plays a part in this also. A normal value of RV is 1.1 in women. You are a tenth of a point being perfect. No need to worry about this!! Hope this helps.