something to consider
I suffer from damage to my autonomic nervous system. Perhaps your CIDP is doing the same to you. Your autonomic nervous system takes care of all the reactions you don’t think about like breathing, pulse, blood pressure adjustments. In my case, changes in body position cause my system to make adjustments that it can’t make properly anymore. Similar to what you mentioned, I can visibly see blood pooling above my knees upon standing. When the blood finally begins to flow properly, it goes too fast causing me lightheadedness. When it initially started, I would have dizziness seated or standing and would have to lie down to alleviate the problem. All of these postural change-related blood pressure things are normally handled by the autonomic nervous system. So abnormally regulated blood pressure then causes the pulse to race to even things out. I have been prescribed Jobst stockings to help regulate the blood flow to my lower legs. Look in to it, if my problem sounds familiar.