Between May 2011 and November 2013 , patients undergoing pancreaticoduodenectomy were enrolled in an institutional review board-approved , single-center , prospective , parallel , randomized controlled trial ( NCT 01428050 ) , comparing lactated Ringers ( LAR ) ( 15 mL/kg/hr LAR intraoperation , 2 mL/kg/hr LAR postoperation ) with HYS ( 9 mL/kg/hr LAR and 1 mL/kg/hr HYS intraoperation , 1 mL/kg/hr HYS postoperation ) .