when I talk about hyperventilating on this blog, unless I mention it as part of something larger (like heart failure) it's to do with anxiety attacks. Anxiety attacks are pretty much self limiting, as people will generally pass out before doing too much damage to themselves. However between anxiety and unconsciousness is some rather painful cramping. Over here 'hypervenitilating' is often a pseudonym for 'panic attack', and 'medically caused' hyperventilating is just given as "resps of 44".