I have appts at Mayo in early December and have been reading about autonomic testing. One of the tests seems real simple - the deep breathing one where you record your heart rate. I have a pulse oximeter and have done this numerous times but my heart rate doesn't change more than 2-4 bpm. I checked that with my bp cuff and they say the same numbers at about the same time. I have a hard time believing that anyone's heart rate REALLY changes 20 bpm from one breath to another. Input?