Ultrasound-assisted translaryngeal block for awake fibreoptic intubation.

To the Editor, The difficulty of identifying landmarks can preclude the success of airway blocks and awake tracheal intubation in patients with challenging airways. We describe a case wherein the use of ultrasound made it possible to perform a translaryngeal block successfully by injection of local anesthetic into the tracheal lumen. This technique allowed subsequent awake intubation in a super morbidly obese patient. Informed consent was obtained from the patient prior to submission of this correspondence. The patient was a 38-yr-old female with a body mass index of 57.4 kg m who was scheduled to undergo a Roux-en-Y gastric bypass. Due to a potential difficult airway, the anesthetic plan was to perform an awake fibreoptic intubation. Preoperatively, the patient’s pharynx was sprayed with a combination of 14% benzocaine and 2% tetracaine. In the operating room, the patient was sedated with midazolam 3 mg iv and ketamine 20 mg iv. She was positioned with her neck extended. An attempt was made to identify the cricothyroid membrane by palpating the space between the cricoid and thyroid cartilages. The midline of the membrane was also located by visual inspection and lidocaine was applied subcutaneously. A 20G catheter over a needle attached to a syringe was slowly advanced through the skin while simultaneously attempting to aspirate air. No air could be aspirated, but a small amount of blood (\1 mL) was obtained. At this point, we reassessed the patient’s anatomy and made another attempt (approximately 1.5 cm below the initial attempt) without success. The translaryngeal block was abandoned and fibreoptic intubation was attempted. Even after injection of 4% lidocaine 4 mL through the side port of the fibrescope, the patient still had a prominent cough reflex which precluded the advancement of the fibrescope below the vocal cords. A portable ultrasound machine, Logiq e, (GE Healthcare, Chalfont, St. Giles, UK) was then brought to the operating room, and the patient’s neck was scanned in an attempt to identify landmarks and the midline. A transverse scan was performed at the level of the thyroid and cricoid cartilages (Figure), and the space immediately below the midline of the thyroid cartilage was marked with a pen. The thyroid cartilage had a hypoechoic inverted V-shape appearance, and the cricoid cartilage had a hypoechoic arch-like appearance. A 20G angiocath was inserted through the patient’s skin and air could then be aspirated into the syringe. The catheter of the angiocath was advanced into the larynx and the metal needle was removed. The patient was asked to exhale; 4% lidocaine 4 mL was injected through the catheter at the end of exhalation and the patient coughed profusely. The fibrescope was then advanced through the patient’s mouth, and the vocal cords were easily visualized. The fibrescope was then inserted below the vocal cords without triggering a cough reflex, and a size 7.0-mm endotracheal tube was passed easily through the vocal cords. Correct placement of the endotracheal tube was confirmed with the fibrescope. Examination of the patient’s neck revealed that the first two attempts were made lateral to the midline. In this case, the use of ultrasound made it possible to perform a translaryngeal block in a patient whose landmarks could not be identified correctly using traditional palpation. This case illustrates a potential clinical application for ultrasound assistance in regional anesthesia G. S. De Oliveira Jr, MD (&) P. Fitzgerald, MS M. Kendall, MD Northwestern University, Chicago, USA e-mail: g-jr@northwestern.edu