Logistic probit regression analysis revealed that the ED and ED ( 95 % CI ) of sevoflurane in neonates were 2.82 % ( 2.66-2 .98 ) and 3.39 % ( 2.89-3 .89 ) , respectively , in the control group ; 2.44 % ( 2.19-2 .68 ) and 3.30 % ( 2.51-4 .09 ) , respectively , in the fent1 group ; and 2.21 % ( 1.97-2 .45 ) and 3.11 % ( 2.35-3 .88 ) , respectively , in the fent2 group .