airway blocks

Question 1

describe glossopharyngeal nerve block

Answer 1

• performed when topical anesthesia does not completely obliterate the gag reflex (usually topical anesthetic is enough)
• branches (lingual) of this nerve are most easily accessed as they transverse the palatoglossal folds
• this block has been reported as painful, and may result in a persistent hematoma (close to the carotid)

Question 2

describe the technique for glossopharyngeal nerve block

Answer 2

• stand contralateral to side to be blocked
• pt.’s mouth wide open
• palatopharyngeal fold (posterior tonsillar pillar) is identified and a tongue blade, held with non-dominant hand, is introduced into the mouth to displace the tongue medially (towards contralateral side) creating gutter b/w tongue and the teeth
• 25 g spinal needle inserted into membrane near the floor of the mouth at the base of the cul-de-sac and advanced slightly (0.25-0.5 cm)
• aspiration test performed: if air, needle has passed through the membrane; if blood, needle is redirected more medially
• 2 ml of 1% lidocaine can be injected into the anterior tonsillar pillar 0.5 cm lateral to the base of the tongue (this most readily blocks the lingual branch)
• do each side

Question 3

what are considerations with a glossopharyngeal nerve block?

Answer 3

• paralysis of the pharyngeal muscles and relaxation of the tongue may cause obstruction of the upper airway
• if this block is performed as well as the SLN block, the glossopharyngeal nerve block should be done last to avoid obstruction

Question 4

describe superior laryngeal nerve (SLN) block technique

Answer 4

• anesthetist positioned on ipsilateral side of the neck
• the cornu of the hyoid bone is palpated with the thumb and the index finger on the side of the neck immediately beneath the angle of the mandible and anterior to the carotid artery
• to facilitate its identification, hyoid bone is displaced toward the side being blocked
• with the same hand displace the carotid artery laterally and posteriorly
• with other hand, a 22g or 23 g, 25 mm needle is walked off the cornu (cartilage) of hyoid bone in an anterior caudad direction, aiming in the direction of the thyroid ligament, until it can be passed through the ligament
• at depth of 1-2 cm, 2 ml of 2% lidocaine with epi is injected (after negative air and blood aspiration) into space b/w the thyrohyoid membrane and the pharyngeal mucosa
• an additional 1 ml is injected as needle is withdrawn
• repeat on both sides

Question 5

what does the SLN block anesthetize?

Answer 5

all laryngeal mucous membranes above the rima glottidis including the epiglottis and the arytenoepiglottic folds

Question 6

describe local anesthetic toxicity

Answer 6

• lidocaine is rapidly absorbed from the very vascular tracheal area into the systemic circulation
• symptoms: ringing in ears, numbness in eyes, potential seizure, potential cardiac effects d/t epi
• max safe dose of topical lidocaine in the trachea is 4 mg/kg
• lowest concentration possible should be used to minimize risk of toxicity