Perhaps I'm missing something and a quick Google provided relatively old results, e.g. a FAA doc from 2012, and a 2004 a.net thread. Unless something has changed (and seemingly "lifeguard" is an outdated term so perhaps I did miss something), why would becoming a "lifeguard" flight cause an apparent 14 minute increase in flight time? That seems to be quite the opposite of the intent; the precious cargo would have arrived earlier had they not been designated for expedited ATC handling.