Alfentanil (Alf) is used in combination with Propofol (Pro) in fiber-bronchoscopy and in many other conscious sedation procedures. Alf and Pro have the characteristic of rapid anesthetic onset and quick recovery, synergic sedative effect and unwanted side effects too. However, the amount of Alf needed in combination with Pro for induction and the timing of administration was no standardized. The investigators designed this study to evaluate the optimal regimen, dose and timing of Alf in Target-Controlled infusion (TCI) of Pro for flexible bronchoscopy sedation.~Method: patients will be enrolled and assigned randomly into five groups. In group 1, normal saline two minutes before and Alf 2.5μg/kg before Pro were given; In group 2, normal saline two minutes before and Alf 5μg/kg before Pro were given; In group 3, Alf 2.5μg/kg two minutes before and normal saline before Pro were given; In group 4: Alf 5μg/kg two minutes before and normal saline before Pro were given; in group 5, normal saline two minutes and before Pro were given.~Concentration of effect site to loss of consciousness (LOC), dose of Pro to LOC, and induction time of variable regimen, as well as hypoxemia, hypotension, cough severity, and Pro injection related pain will be recorded and analyzed.
Alfentanil (Alf) is used in combination with Propofol (Pro) in fiber-bronchoscopy and in many other conscious sedation procedures. Alf and Pro have the characteristic of rapid anesthetic onset and quick recovery, synergic sedative effect and unwanted side effects too. However, the amount of Alf needed in combination with Pro for induction and the timing of administration was no standardized. The investigators designed this study to evaluate the optimal regimen, dose and timing of Alf in Target-Controlled infusion (TCI) of Pro for flexible bronchoscopy sedation, and also to evaluate the influence of variable regimen of Alf and Pro on hypoxemia, hypotension, cough severity, and Pro injection related pain.