The Collaborative International Dictionary of English v.0.48:

Impulsively \Im*pul"sive*ly\, adv.
   In an impulsive manner.
   [1913 Webster]

WordNet (r) 3.0 (2006):

impulsively
    adv 1: in an impulsive or impetuous way; without taking
           cautions; "he often acts impulsively and later regrets
           it" [syn: impetuously, impulsively]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "impulsively":
   a corps perdu, abruptly, at half cock, bang, capriciously,
   chaotically, dash, erratically, every which way, hastily,
   head over heels, headfirst, headforemost, headlong,
   heels over head, helter-skelter, higgledy-piggledy, impetuously,
   in a rush, inconsistently, inconstantly, irregularly, like a flash,
   like a thunderbolt, nonuniformly, of a sudden, on short notice,
   overhastily, oversoon, plop, plump, plunk, pop, precipitantly,
   precipitately, precipitously, prematurely, quickly, rashly,
   recklessly, sharp, slap, slap-bang, smack, spasmodically,
   sporadically, startlingly, sudden, suddenly, surprisingly,
   too early, too soon, unawares, unequally, unevenly, unexpectedly,
   unsteadily, unsystematically, untimely, ununiformly,
   without notice, without warning