Nebulized dexmedetomidine-lidocaine inhalation as a premedication for flexible bronchoscopy: a randomized trial

Background: Dexmedetomidine plus opioid infusion after topical anaesthesia with nebulized lidocaine for cough suppression is a commonly used method for flexible bronchoscopy. Recently, the use of dexmedetomidine as an additive to local anaesthetics has been reported to have several advantages over conventional intravenous administration. However, there are no data regarding the use of nebulized dexmedetomidine-lidocaine for topical anaesthesia as a premedication for flexible bronchoscopy. Therefore, this study compared the tolerability and safety of nebulized dexmedetomidine with that of conventional intravenous administration in patients undergoing bronchoscopy with moderate sedation. Methods: Sixty patients requiring flexible bronchoscopy were randomly assigned to three groups: (I) nebulized dexmedetomidine + lidocaine, n=20; (II) intravenous dexmedetomidine + nebulized lidocaine, n=20; and (III) nebulized lidocaine alone (no dexmedetomidine), n=20. The patients' coughing scores were assessed and graded. Our primary hypothesis was that nebulized dexmedetomidine-lidocaine could reduce the incidence of moderate to severe coughing. The secondary endpoints were the rates of glottis closure, complete jaw relaxation and limb movement during the procedure; the elapsed time until recovery; and the dosages of vasoconstrictors and atropine. Results: The incidence of moderate to severe coughing was 15% in the nebulized dexmedetomidine group, 50% in the intravenous dexmedetomidine group and 55% in the no dexmedetomidine group. The nebulized dexmedetomidine group had the lowest incidence of moderate to severe coughing (P=0.019). Nebulized dexmedetomidine showed a protective effect for reducing coughing compared with intravenous dexmedetomidine [P=0.008, odds ratio (OR): 0.273, 95% confidence interval (CI): 0.089-0.833]. No differences in the rates of complete jaw relaxation and limb movement during the procedure were observed among the three groups (all P>0.05). The rates of glottis closure were similar (20%, 25%, and 35%; P>0.05). The elapsed time until recovery in the nebulized dexmedetomidine group was significantly shorter than that in the intravenous dexmedetomidine group (10.60 +/- 1.39 vs. 15.10 +/- 1.45, P<0.001). The vasoconstrictor dosages were significantly lower in the nebulized dexmedetomidine group than in the intravenous dexmedetomidine group (P<0.001). Conclusions: Nebulized dexmedetomidine-lidocaine inhalation as a premedication for flexible bronchoscopy was well tolerated during bronchoscopies performed under moderate sedation and was associated with a reduced incidence of moderate to severe coughing, a shorter recovery time and reduced vasoconstrictor consumption.