The Collaborative International Dictionary of English v.0.48:

Perfusion \Per*fu"sion\, n. [L. perfusio.]
   The act of perfusing.
   [1913 Webster]

WordNet (r) 3.0 (2006):

perfusion
    n 1: pumping a liquid into an organ or tissue (especially by way
         of blood vessels)

Moby Thesaurus II by Grady Ward, 1.0:

82 Moby Thesaurus words for "perfusion":
   arterial transfusion, blood bank, blood donor, blood donor center,
   blood transfusion, bloodmobile, communication, conduction,
   contagion, convection, delivery, deportation, diapedesis,
   diffusion, direct transfusion, dissemination, drip transfusion,
   embedment, entrance, exchange transfusion, export, exportation,
   expulsion, exsanguination transfusion, exsanguino transfusion,
   extradition, graft, grafting, impaction, impactment, implantation,
   import, importation, infixion, infusion, injection, inoculation,
   insertion, insinuation, interchange, interjection, interpolation,
   introduction, intromission, metastasis, metathesis, metempsychosis,
   migration, mutual transfer, osmosis, passage, passing over,
   penetration, plasma transfusion, reciprocal transfusion,
   replacement transfusion, serum, serum transfusion, spread,
   spreading, tessellation, transduction, transfer,
   transfer of property, transference, transfusion, transit,
   transition, translation, translocation, transmigration,
   transmigration of souls, transmission, transmittal, transmittance,
   transplacement, transplant, transplantation, transposal,
   transposition, travel, venous transfusion