A senior anaesthesiologist will perform airway assessment to determine the predicted difficult airway as per inclusion criteria mentioned above. Patients shall be kept fasting as per the standard guidelines and will receive premedication as per the decision of anaesthesiologist. In the operation theatre, an intravenous line will be secured and standard monitoring will be attached using a multichannel monitor and baseline parameters consisting of heart rate, peripheral capillary oxygen saturation (SPo2), non-invasive blood pressure (NIBP) shall be recorded. As per standard protocol of managing a difficult airway, a difficult airway cart will be kept and another senior anesthesiologist shall remain on standby while securing the airway. All patients will be positioned in the sniffing position. Patients will be randomized into two groups i.e. Group-VL, Group-FVL (FB+VL). According to the group allotted, the respective devices shall be prepared. In Group VL an endotracheal tube (ETT) loaded over a stylet shall be kept ready and in Group FVL an ETT loaded over the flexible bronchoscope shall be kept ready.

A standard anesthetic technique will be adopted for all patients. Patients will receive injection fentanyl 2 µg/kg iv and general anesthesia will be induced with injection propofol 2-2.5 mg/kg i.v. After checking adequacy of mask ventilation, muscle relaxation will be achieved with injection rocuronium 0.6 mg/kg iv and tracheal intubation will be attempted after 3 minutes of intermittent positive pressure ventilation (IPPV) with oxygen and 2% sevoflurane, with an appropriately sized PVC tracheal tube by C-MAC video laryngoscope in Group VL. In Group FVL, first the VL shall be introduced and once the glottis is visualized, another anesthesia provider shall insert the FB and taking clues from the VL view, FB guided intubation shall be performed. The intubation will be performed by a senior anesthesiologist experienced for at least 10 years with both the devices. Tube position will be checked by auscultation and confirmed by capnography. Time taken for tracheal intubation will be defined as the time from introduction of laryngoscope to the appearance of first square wave capnographic trace. Time taken for tracheal intubation will be recorded by stopwatch. Optimal External Laryngeal Manipulation (OELM) shall be allowed for achieving successful intubation and number of patients requiring application of this maneuver will be recorded. Any evidence of oro-dental trauma in terms of injury to lips, teeth, gums, and mucosa of the oropharynx shall be observed and recorded while withdrawing the device after the endotracheal intubation is achieved. After successful tracheal intubation, anesthesia will be maintained with sevoflurane in air and oxygen along with top ups of inj. rocuronium.

 Failure of intubation shall be defined if more than two attempts are taken to secure the airway with either of the 2 techniques. In such a situation the airway will be secured as per the anesthesiologist discretion and the patient will be excluded from the study. 

Intraoperative hemodynamics will be managed in accordance with surgical procedure and blood loss. 

Trachea will be extubated as per standard protocol using inj. neostigmine 0.05 mg/kg iv and inj. glycopyrolate 0.01 mg/kg iv.