Guess it's pots, not OI . Pounding, fast pulse. Blood pressure was 138/70. It usually runs low like 129.
I think different autonomic specialists use different terms but OI (Orthostatic Intolerance) is often used as an umbrella term for any type of problem maintaining heart rate and/or blood pressure while in an upright position. And POTS is a subset.
For example, the Johns Hopkins patient handout uses OI as an umbrella term that covers POTS and NMH (aka, NMS):
http://www.dysautonomiainternational.org/pdf/RoweOIsummary.pdf
But there are other uses. Vanderbilt seems to use POTS and OI as synonyms on this page:
http://www.mc.vanderbilt.edu/root/vumc.php?site=adc&doc=38847
This article on medscape used to use the term COI (Chronic Orthostatic Intolerance) instead of OI. But I think the article remove that usage (my memory is not clear and I did not re-read the whole article):
http://emedicine.medscape.com/article/902155-overview
And I think dinet.org uses the term OI in a somewhat different way:
http://dinet.org/index.php/information-resources/pots-place/pots-overview
Trouble breathing? Never heard that as a symptom.
Feeling short of breath is how I usually describe it. I don't know how that differs from air hunger.
It's not like asthma or that type of trouble breathing. For me it's like I've been running and can't catch my breath. I used to do a lot more taking deep breaths, almost instinctively, because that worked when I was healthy (imagine after running you are breathing hard but after a few minutes you feel normal again).
But with this illness the deep breaths don't make everything go back to normal. It takes a lot of resting for my heart rate & breathing to settle down. No anxiety at all. Just short of breath, dizziness, nausea, exhaustion, rapid heart rate, chest pains, etc.
List of POTS symptoms on dinet.org:
http://dinet.org/index.php/information-resources/pots-place/pots-symptoms
And Phoenix Rising has a page listing OI symptoms:
http://phoenixrising.me/symptoms-of-orthostatic-intolerance
Sorry to ramble on, hope this is helpful to someone out there...