HematocritDigestive System DiseasesErythropoietinAnemiaOrthognathic Surgical ProceduresPhlebotomyHemodilutionPolycythemiaHemoglobinsBlood Loss, SurgicalRenal DialysisKidney Failure, ChronicIronRetrospective StudiesRecombinant ProteinsBlood ViscosityTreatment OutcomeErythrocyte CountPlasma VolumeErythrocyte VolumeBlood VolumeExchange Transfusion, Whole BloodErythrocyte Indices