Target-Controlled Infusion of Propofol for Flexible Bronchoscopy Sedation

Target-Controlled Infusion of Propofol for Flexible Bronchoscopy Sedation: Determining the Optimal Titrating Regimen

Flexible bronchoscopy (FB) sedation requires keeping sedative level in a narrow window to prevent over or under sedation. Sedative drug titration according to subjective adjustment by individual physician may cause unsteady drug concentration. Target controlled infusion (TCI) has been provided a precise pharmacokinetic control of propofol, direct control the effect side, (eg. Brain) concentration (Ce), and been applied in surgical anesthesia and variable procedure sedation. We designed this pilot study to evaluate the optimal regimen of TCI in FB sedation.

Propofol is ideal for bronchoscopy sedation because of its fast onset and quick recovery effect. Our research and reports from different investigators demonstrate that patients received propofol sedation recover fast with excellent satisfaction for bronchoscopy. However, the amount of propofol for induction and maintenance is calculated simply by patient's body weight and physicians' experience. For those non-anesthesiologists, who perform sedative work outside the operating room, and inexperienced anesthesiologist without fully considering the individual pharmacokinetic and pharmacodynamic differences may generate unstable drug plasma concentration and increase cardio-respiration suppression. Therefore, a manner which can assess and measure objectively individual pharmacokinetic differences may improve the sedative quality and decrease the complication rate.

A model called "Target-controlled infusion"(TCI), built from massive pharmacokinetic samples of propofol, could now give precise pharmacokinetic control. Several pharmacokinetic models built-in in TCI, includes the Schnider model which use concentration of effect site (Ce, the propofol concentration in the brain) as the sedative guide. The model integrates individual variants of age, height, weight and gender to calculate the infusion profile to achieve predetermined steady "target effect site concentration" (Cet). Because of the unique consideration of individual pharmacokinetic variants and Ce targeting, TCI provides predictable sedative level and is suitable for procedures requiring narrowing therapeutic level. Beside general anesthesia, TCI has been applied in breast biopsy, upper gastrointestinal endoscopic ultrasound and endoscopic retrograde cholangiopancreatography at outpatient clinic. According to these evidences, there is potential role of TCI in bronchoscopic sedation.

Based on current evidence and our experience, we design this study to evaluate the optimal regimen for induction and procedure during bronchoscopy. We hope this study could provide the more safety and efficient bronchoscopic sedation for patients and physicians.

Inclusion Criteria:

• Adult patients (18 years old or more) required elective flexible bronchoscopy and sedation.

Exclusion Criteria:

• American Society of Anesthesiologists classification of physical status 4 and 5, including hepatic or renal failure, severe obstructive sleep apnea and severe chronic obstructive pulmonary disease.
• Mallampati score 4 or 5.
• Significant Central nervous system disorders or other factors contributing to access consciousness difficultly.
• Men with body mass index(BMI) large than 42，Females with BMI large than 35.
• Allergic history to study drugs.