Patients undergoing flexible bronchoscopy (FB) experience procedure-related symptoms. Current guidelines of FB recommend sedation to all patients undergoing FB, except when there are contraindications. Propofol plus an opioid is the common combination used to improve patient tolerance and satisfaction during FB. However, controversy about combining propofol and opioids persists because of the risk of over-sedation and cardiopulmonary depression, especially for the time-consuming endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA). Similar with other published data, around 40% of hypoxemia event was observed during FB sedation in the investigators' hospital. Dexmedetomidine, is a sedative agents via α2 adrenergic agonist, with little respiratory suppression. It has been applied in patients with mechanical ventilation, undergoing gastroendoscopy and extracorporal shockwave lithotripsy. Little evidences are available for Dexmedetomidine in sedation for EBUS-TBNA.~In this study, the investigators will evaluate the safety and feasibility of Dexmedetomidine for sedation of EBUS-TBNA comparing to Propofol for sedation of EBUS-TBNA. Generally, the FB sedation can divided into three parts: the induction (from starting sedative administration to insertion of bronchoscope); the maintenance ( from insertion of bronchoscope to its removal) and the recovery (from bronchoscope removal to patients gain consciousness). The primary endpoint is the proportion of patients with hypoxemia during maintenance of sedation. the investigators will also observe the other sedative outcomes, e.g. blood pressure, sedative drug dosing and patient tolerance and cooperation. The present study will also observe the association between brain perfusion and sedative outcomes via non-invasive monitor. Based on the unique pharmacokinetic property of Dexmedetomidine and the real-time brain perfusion monitor, Dexmedetomidine-based sedation may provide better safety profile for EBUS-TBNA than propofol and discover novel connection between sedative outcomes and brain perfusion.
Preventing hypoxemia is one of the major goal of studies for bronchoscopic sedation. Dexmedetomidine is a sedative agents via α2 adrenergic agonist, with little respiratory suppression. In the preset study, we evaluate the safety and feasibility of the Dexmedetomidine in the specific bronchoscopic procedure, endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration.