I've been experiencing panic attacks since I was in high school, not that I knew what they were at the time. One moment I'd be fine and the next I'd be sat on the floor hyperventilating in fear and being transported around school in a wheelchair because I was unable to stand. For the longest time I thought that being unable to breath properly was the only symptom, not attributing anything else to my struggle with anxiety.
Since then I've realised that so many more of the symptoms I experience, collapsing, being completely unable to focus and wondering around in a complete daze, are all connected to feeling anxious. Right now, for instance, I'm attempting to work on an article while my brain is spinning and my chest feels tight, I feel nauseas, guilty and could burst into tears at any moment, the fact that I'm able to write this post is a miracle in itself. Thankfully I'm slowly calming down and, once I've given myself adequate time to feel better, I should hopefully be able to continue with my work by 11 o'clock. Time really is the best healer for me in these situations.
What I think is important is that people realise how many different symptoms can be attributed to anxiety. I'm not saying that everyone who's ever felt a little bit on edge or frightened should be diagnosed, but I know that once I realised my random collapsing was a result of anxiety I was able to learn how to make myself feel better. Drinking a cup of tea with enough sugar to have an entire playgroup bouncing off the walls and lying on my back with my legs in the air is far more helpful than a hundred and one people crowding around me, thinking I need to be taken to hospital and making me feel 100 times worse for wasting their time.
For some people, hyperventilating may be their only symptom, and they should be helped in a way that best suits them. Fresh air, space, anything they need to allow them to feel better. What is important is to not dismiss or ignore what you or the person involved may be feeling. Just because you don't recognise something as a more traditional or tell tail sign, does not mean that the person in question is not being affected by their anxiety in a lesser way.
What I found most helpful was to learn what may be a part of a panic attack for me, and what may not. One of the problems with mental illness is that so few attributes are one size fits all, and it's important that everybody knows and understands their symptoms, so as not to make themselves feel any worse than they already do.