The mean SPC was 42.3 gml ( -1 ) [ 95 % confidence interval ( CI ) 40.0 to 44.6 ] in group Sevo1 .8 % and 21.0 gml ( -1 ) ( 95 % CI 18.8 to 23.3 ) in group SevoBIS , representing a 50.2 % reduction ( P < 0.001 ) .