I suffered from panic attacks and but I never blacked out... My psychologist told me that in the midst of an attacks, one has to be careful of overbreathing because it will cause more dizziness...

So the answer is nope - I never suffered an attack this bad but I had on occasions had 2 attacks in a row and it usually leave me so drained, I will be very pale and weak on top of being disappointed with myself.

Oh and if you are on meds, be very careful not to abuse them, it makes matters worse cos the meds are supposed to help...

I'm on fluoxetine for depression and it's supposed to help with my anxiety (though I don't see it happening and i've been on it for 6 weeks!) and clonazepam (as and when needed) to help me sleep...

Feel for you as I've been through it. Tell your doc, he should be able to help you through it.

Cheers!