If you have asma, the best advice I can give you is to either avoid it completely or play it only with a partner.
Besides that, make absolutely sure you have a working set of sissors with you before you start. I mean, hold the sissor and actually cut the thread's tip fore you begin with your own hand, or have your dom cut it in front of you (which would be more appropriate).
If you take a blind chance, you get an asma attack while mummified, and you cannot count with somebody else to freed you, it will be most likely all over for you.