Adults with insertion of a nontunneled , nonantimicrobial-impregnated double-lumen DC for an expected duration greater than 48 hours , to perform renal-replacement therapy or plasma exchange , were randomly allocated ( 1:1 ) to receive a 2-minute catheter lock with either 60 % wt/wt ethanol solution ( ethanol group ) or 0.9 % saline solution ( control group ) at the end of DC insertion and after each renal-replacement therapy or plasma exchange session .