Anesthesia of the airway by aspiration of lidocaine

Purpose: Lidocaine instilled onto to the back of the tongue of a supine sub ject and aspirated has been reported to provide effective topical anesthesi a of the airway, The purpose of this study was to observe endoscopically th e fate of lidocaine so instilled and document the efficacy of anesthesia fo r awake fibreoptic intubation. Methods: In Part 1 of the study, a fibreoptic bronchoscope was positioned i n the pharynx of three volunteers lying supine and the route followed by ti nted lidocaine solution instilled onto the back of the protruded tongue dur ing mouth breathing was observed. In Part 2, the airway of 39 patients requ iring awake fibreoptic intubation was anesthetized by having them gargle tw ice with 5 mt lidocaine 2%, followed by instillation of 0.2 ml.kg(-1) or 20 mi lidocaine 1.5% (whichever was less) onto the dorsum of their tongues as described above. The efficacy of anesthesia was scored by the patient reac tion (coughing or gagging) to instrumentation in the pharynx, at the glotti s, and in the trachea; to passage of the tracheal tube into the trachea; an d to the presence of the tube in the trachea. Results: Lidocaine instilled on to the back of the tongue was swallowed ini tially but ultimately pooled in the pharynx and was aspirated. In all patie nts the trachea was intubated without requiring supplemental lidocaine, and all but one patient tolerated the tracheal tube in situ. Conclusion: A combination of lidocaine gargles and lidocaine instilled on t o the back of the tongue and aspirated provides effective anesthesia of the pharynx, larynx, and trachea for awake fibreoptic intubation.