The study design also allowed for administration of open-label C1INH-nf for laryngeal angioedema attacks, which were non-randomizable events due to the presence of or potential for airway compromise (immediate 1,000 U dose of C1INH-nf, repeated after 60 minutes, if necessary). In addition, subjects were eligible to receive open-label C1INH-nf (1,000 U single dose) prior to emergency surgical (non-cosmetic) procedures.