a single bolus of fentanyl 30 micrograms kg-1 ( group i , n = 5 ) or alfentanil 120 micrograms kg-1 ( group ii , n = 7 ) was given after the induction of anaesthesia and repeated 1 h later , immediately before the surgical incision .
C0015846
fentanyl
C0002026
alfentanil