RESULTS	The total time of the procedure was longer for the alfentanil/propofol group ( median = 11 minutes , range = 5-22 minutes ) than for the propofol group ( median = 9 minutes , range = 1 to 43 minutes ; effect size = 1.93 minutes , 95 % CI = 0.73 to 2.58 , p = 0.02 ) .\