Shortness of breath on Nxstage

Have you ever heard of someone having mild shortness of breath for about 30 minutes after starting on Nxstage treatment? The person I help with Nxstage was fine incenter. Now that he has started HHD he has mild distress after about 15 minutes on treatment and then it totally resolves after 30 to 45 minutes. The physician or nurse had never heard of this, an echo was ordered- normal, lungs checked-normal, labs reviewed- normal. I’ve done some research both through nxstage and looking for scholarly sources, but haven’t been able to find any other issues similar to this. Any advice where to look or what maybe causing this?

Put a plus oximetry on her finger and let me no the results. I had one of patent like this back in 2014 . They where but on oxygen for 1 hour never did find out what caused it. It finality went away after 6 month