Awake Fiber Optic Intubation (AFOI) in Patients With Stenosis of the Upper Airway: Utility of the Laryngeal Nervous Block

Patients will be randomized in two groups: group A: treated with continuous infusion of remifentanil, topic anesthesia of the base of the tongue, intercricoid block and SLNB; group B: treated with continuous infusion of remifentanil, topic anesthesia of the base of the tongue and intercricoid block. After the first measurement of vital parameters (T0), patients will received a continuous intravenous infusion of remifentanil at a rate ranged between 0.05 and 0.15 mcg/kg/min, reached by titration of a conscious sedation plane corresponding to the 0/-1 stage of the RASS scale. In all patients of both groups topical anesthesia of the oropharynx mucosa will be performed through 10 puffs of 10% lidocaine spray at the back of the tongue and at the base of the palatopharyngeal and palatoglossal arch. In Group A SLNB will be performed by administering 4 ml of 1.5% lidocaine below the thyroid membrane, which is palpated in addition to the intercricoid block by translaringeal puncture and 4 ml of lidocaine 1,5%. In group B intercricoid block will be performed by translaringeal puncture and 4 ml of 1.5% lidocaine. Group B will receive placebo instead of the regional block. After regional anesthesia, the patient will be placed on the operating table with the head in a neutral position. The vital parameters and the level of sedation reached (T1) will be registered. If SpO2 will be less than 96%, the patient will be pre-oxygenated with FiO2 100%. AFOI procedure will be performed using a 4 mm Olympus LF-2 bronchoscope and spiral tracheal tubes (internal diameter of between 5-6 mm) will be used. Discomfort during AFOI will be evaluated through the Fiber Optic Intubation Comfort Score. During AFOI procedure, unstructured airway maneuvers (neck's hyperextension, jaw subluxation, and pulling the tongue manually) will be evaluated. Hypoxemia, aspiration of secretions and time to perform intubation will be reported.

After intubation, a new evaluation of the vital parameters will be performed (T2) and patients will undergo to a total intravenous general anesthesia in accordance with the current international protocols. The primary endpoint will be to evaluate if SLNB is able to reduce the degree of discomfort of the AFOI procedure measured with the relative risk of Fiber Optic Intubation Comfort Score > 1. Secondary endpoint will be incidence of hypoxemia, time required to intubate, intraprocedural hemodynamic stability, airway obstruction score, need to aspirate secretions during AFOI, Tracheal Tube Tolerance Score.