 This is a randomized, open-label study designed to assess the safety and efficacy of AQUAVAN Injection versus midazolam HCl following pretreatment with an analgesic, fentanyl citrate injection, in producing sedation in patients undergoing a flexible bronchoscopy procedure. Randomization will be stratified by site. Following completion of pre-procedure sedation assessments, patients will be randomly assigned to 1 of the 2 i.v. treatment groups at a 3:1 AQUAVAN Injection: midazolam HCl allocation ratio. 