US-guided Airway Nerve Block vs. Topical Lidocaine in Video Laryngoscopy for Difficult Bariatric Intubation.

A.Preoperative settings:

A thorough preoperative evaluation including a complete airway evaluation (mouth opening, mallampati grading, body weight, thyromental distance, and evaluation of dentition) will be performed. Standard fasting guidelines and anti-aspiration prophylaxis with tablet ranitidine 150 mg will be prescribed.

The patients will be explained about the awake C-MAC intubation during preoperative assessment.Injection of atropine 0.4 mg will be given half an hour before shifting the patient to the operating room (OR).

B.Intraoperative and postoperative settings:

Injection of atropine 0.4 mg will be given half an hour before shifting the patient to the operating room (OR). Inside the OR, standard monitoring, including electrocardiography (ECG), noninvasive blood pressure (BP), and pulse oximetry (SpO2) will be applied in all patients. An intravenous (IV) line will be secured and ringer lactate will be started. After recording the baseline heart rate (HR), BP and SpO2, Injection of Dexametomidate 0.7 mcg/kg/hr IV infusion and injection ketamine 0.5-2 mg/kg slow IV single dose until endotracheal tube secured.

For each group, local anesthetics will be given in first group (LA)guided by ultrasound and second group (T) with topical method until Adequate effect of local anesthesia confirmed by hoarseness of voice in Group LA patients and numbness of tongue in Group T patients. While giving supplemental oxygen through nasal prongs, C-MAC intubation will be performed. After the airway is secured, general anesthesia will be administered with propofol 2 mg/kg, and rocuronium 0.6 mg/kg.

Postoperatively, patient comfort will be assessed for sore throat, dysphagia, voice change, or any lip, gum, tongue, dental injuries, complete amnesia, partial recall, and unpleasant memories during awake C-MAC intubation.

• Ultrasound guided airway nerve block for Endotracheal intubation (Procedure): Glossopharyngeal nerve block: 1.5 mL 2% lidocaine, ultrasound probe on lateral neck below mandible, landmark = hyoid bone, tilt cephalad to target pharyngeal wall near tonsil; right side needle inserted out-of-plane from superior probe edge to avoid artery. Bilateral superior laryngeal nerve blocks: out-of-plane at lateral thyroid cartilage, orient probe medially, inject 1 mL 2% lidocaine into thyrohyoid membrane between hyoid and thyroid cartilage using 25-G 25 mm needle. Bilateral recurrent laryngeal nerve blocks: translaryngeal out-of-plane, locate cricothyroid membrane below thyroid cartilage, insert 25-G 25 mm needle 1.5 cm, confirm air backflow, inject 2 mL 2% lidocaine.
• lidocaine topical anesthesia for Endotracheal intubation (Procedure): will receive topical lidocaine 10% spray directly on the tongue and oropharynx without exceeding toxic doses.

Primary outcomes

• Incidence of Gag reflex and cough reflex [After applying local anesthesia by at least 3 minutes]: After taking local anesthesia monitoring of gag and cough reflexes will be monitored during the process of endotracheal intubation

Secondary outcomes

• Mean blood pressure (MAP) [After applying local anesthesia by at least 3 minutes]: After taking local anesthesia monitoring of Mean blood pressure (MAP) will be monitored during the process of endotracheal intubation

Sex: All, ages: 21 Years to 65 Years, accepts healthy volunteers

Inclusion Criteria:

1. Age: 21-65 years old
2. Obese patients (BMI>35 kg/m2) undergoing bariatric surgery
3. Suspected difficult intubation: e.g:(Mallampati score ≥3 , Thyromental distance <6 cm, Limited neck mobility, History of difficult intubation)
4. ASA I-II

Exclusion Criteria:

1. Patients at increased risk for aspiration (e.g., full stomach or gastro-esophageal reflux disease) and pregnancy
2. Patients with expected difficult ventilation
3. Patients who have upper airway pathology or surgery
4. Patients with a mouth opening < 2 cm
5. ASA III-IV
6. Emergency surgery
7. Allergy to local anesthetics
8. Contraindication to nerve blocks e.g.:(Coagulopathy, Infection at site of injection)
9. Patient refusal
10. Neurological or cognitive impairment making the patient uncooperative
11. History of difficult airway complications e.g.: previous intubation failure or need for surgical airway
12. Cervical spine instability or fractures

• Results publication: Hashim RM, Zaki MSM, Elagiby DBN, Taher IAA. Ultrasound-Guided Airway Nerve Blocks vs. Lidocaine Topical Anesthesia Using Video-Assisted Laryngoscopy in Suspected Difficult Intubation for Patients Undergoing Bariatric Surgery: A Randomized Clinical Trial. Anesthesiol Res Pract. 2026 May 22;2026:2054379. doi: 10.1155/anrp/2054379. eCollection 2026. PMID 42180592

• David B Nabih, M.B.B.CH, Principal investigator, Anesthesia resident Ain Shams University