Phil,
I have bipolar disorder and anxiety attacks come with the territory. At my worst in my early twenties, I would have up to six or seven in a day. They are very distressing, debilitating and disturbing to others when they occur.
First and foremost: You can not die from an anxiety attack, no matter how distressing it is.
Over time, regular sufferers can become able to recognise the triggers and learn to either face or avoid them CBT is useful for this. Quite often though, attacks appear very unpredictably and the sufferer develops a mindset of anxiety about having an anxiety attack. Metaphorically walking blindfolded through a minefield, this in itself becomes a trigger.
At the extreme height of my symptoms I was diagnosed with Diazepam, which basically acts like a bat around the head and relieves symptoms very quickly. This isn't useful as a long term measure as it's very addictive. I've also tried beta-blockers (Propanalol) which slow the heart rate and are often used by performers for stage fright.
As mammutly says, get your mum to her GP who as well as prescribing medicines can access other treatments like counselling and CBT (both of which work well).
In the meantime, there are loads of great books out there and some top websites.
<a class="postlink" href="http://www.mind.org.uk/help/diagnoses_and_conditions/panic_attacks" onclick="window.open(this.href);return false;">http://www.mind.org.uk/help/diagnoses_a ... ic_attacks</a>
<a class="postlink" href="http://www.nhs.uk/Livewell/phobias/Pages/Panicattacks.aspx" onclick="window.open(this.href);return false;">http://www.nhs.uk/Livewell/phobias/Page ... tacks.aspx</a>