Comparison between lignocaine nebulization and airway nerve block for awake fiberoptic bronchoscopy-guided nasotracheal intubation: a single-blind randomized prospective study

Airway management is an important part of anesthesia, providing ventilation, oxygenation, preventing aspiration, and working as a mode of distribution anesthetic gasses. This is an important skill and area of focus for the anesthetist because sometimes it is very difficult to maintain or manage the airway and this can be life-threatening. The awake fiberoptic endoscope intubation (AFOI) technique is the gold standard in the treatment of patients with suspected airway difficulty, especially before induction of anesthesia.1 It is important to prepare patients before AFOI. The thought of being awake and having a nasotracheal procedure can be very stressful for a patient who is not mentally prepared, so adequate time and effort should be spent preparing patients and by using different pharmacological modalities. The anesthesiologist should guide and prepare the patients by explaining procedure in details in their mother tongue. 2 Preparation also includes blocking airway reflexes, providing adequate sedation, preventing anxiety and maintaining airway patency and adequate ventilation. Awake fiberoptic intubation includes facial fractures, cervical spine instability,some partial obstructive laryngeal lesions (e.g., papilloma), craniofacial abnormalities, and temporomandibular joint ankylosis. 3,4 It can also be used to maintain the patency of airway in several conditions like in cervical spine unstability where manipulation of patient’s neck is likely to be difficult. In cases where cervical spine immobile or instable, applying of rigid cervical collar can reduce cervical spine movements and it hampers tracheal intubation by using standard laryngoscope.5 This procedure reduces the risk of nerve damage before the onset of surgical procedure. Before intubation under awake FOB guidance, it is essential to sufficiently anesthetize upper airway and suppress the swallow, gag and coughing reflexes prior to guided intubation and thus ensure patient comfort.6 This can be attained by different ways, which can be divided into two groups: (a) Local application of local anesthetic agent, or (b) blockade of neural supply to oropharynx and larynx.Local applications of LA in sprays, mouthwashes, lozenges, or nebulized forms cause less damage to the airway compared to nerve blocks. Also, the risk of inadvertent injection into blood vessels is avoided. In contrast, nerve block techniques usually require a small amount of local anaesthetic, which may reduce risk of systemic toxicity. 7Airway nerve blocks are in the form of glossopharyngeal, superior laryngeal (SLN) and trans tracheal block to abolish gag reflex, closure of the glottis and reflex coughing. 8 To complete anesthesia, it is recommended to block the glossopharyngeal nerve (GPN) and superior laryngeal nerve (SLN) both sides and transtracheal injection for recurrent laryngeal nerve. Glossopharyngeal nerve can be blocked intraorally and extraorally but it is associated with complications and it is recommended not to use the later approach due to close proximity of the vagus nerve. 9 Airway nerve blocks are mostly used for awake fiberoptic intubation because they provide rapid and deep anesthesia. Nebulization of local anesthetics is also effective technique, which provide complete anaesthesia without the need for multiple painful injections. Therefore, we will compare nerve block, which is considered the standard procedure for achieving rapid and effective airway anesthesia, with lignocaine nebulization, which constitutes a simple, painless, and comfortable alternative method for anesthetizing the airway. When carried out under minimal sedation these techniques help to allay anxiety so the patient is more cooperative during the procedure. In our study, before awake fiberoptic bronchoscopy-guided intubation, we used dexmedetomidine infusion for procedural sedation, which results in a stable hemodynamic profile and prevents desaturation by preserving the respiratory function of the patient. This randomized study will be conducted to compare the efficacy of jet nebulization of lignocaine and airway nerve block for providing airway anesthesia before awake fiberoptic bronchoscopyguided intubation.