Ultrasound-guided superior laryngeal nerve block and translaryngeal block for awake tracheal intubation in a patient with laryngeal abscess

Abstract

To the Editor: When airway management is anticipated to be difficult, awake intubation using a fiberoptic bronchoscope (FOB) is indicated [1]. To achieve successful awake intubation, patient cooperation in combination with appropriate local anesthesia is essential. Superior laryngeal nerve block (SLNB) is an airway anesthesia technique that can paralyze the lingual radix, epiglottis, and cricothyroid muscle, and is thus expected to suppress the gag and cough reflexes. SLNB has conventionally been performed with palpation of the greater horn of the hyoid as an anatomical landmark. The needle is inserted in an anteroinferomedial direction until the lateral aspect of the greater horn is contacted, and local anesthetic is then injected while the carotid artery is displaced posteriorly. However, it is sometimes difficult to recognize landmarks when the patient is obese or has an anatomical abnormality due to a pathology. Ultrasound-guided nerve block has been widely used recently, and this technique can provide visual information on the anatomy [2]. Here, we report a case in which awake tracheal intubation was performed under ultrasound-guided bilateral SLNB. A 19-year-old female complained of submental pain after odontotherapy, and she was scheduled for incisional drainage of a laryngeal abscess. As the abscess involved the medial pterygoid muscle (Fig. 1a), she presented restricted mouth opening (less than one finger). After obtaining written informed consent, semi-awake FOB intubation under nerve block was scheduled. Prior to nasal FOB intubation, 2 mg of midazolam and 50 lg of fentanyl were administered. Nasal mucosa was topicalized with 8 % lidocaine. Although we attempted to perform SLNB, her left hyoid bone was difficult to find by palpation. However, when we scanned her neck using US (5–10 MHz linear probe, S-Nerve, Sonosite Japan, Tokyo, Japan), the bone was easily identified in the transverse view. The distance from the skin surface to the bone was measured as 1.1 cm, and neither vessel nor abnormal structure was observed. With a 22G needle, 2 ml of 2 % lidocaine were injected into the surface of the greater horn of the hyoid under ultrasound guidance in an in-plane configuration (Fig. 1b). The procedure was repeated on the right side. The tracheal membrane was also topicalized with ultrasound-guided translaryngeal block through the cricothyroid membrane. Ultrasound-guided SLNB seemed effective and FOB intubation was successfully performed while the patient was semi-awake without any discomfort. The patient complained of slight hoarseness after surgery but this disappeared within a day. There was no other notable complication. We have previously reported ultrasound-guided translaryngeal block through the cricothyroid membrane for awake The work was attributed to both the Department of Anesthesiology and Critical Care Medicine and the Department of Emergency Medicine and Intensive Care at Asahikawa Medical University.