Anesthesia for ENT and Maxillofacial Surgery Flashcards
What is the Larynx?
The larynx is a rigid organ composed of three paired and three unpaired cartilages (arytenoid, corniculate, and cuneiform; and thyroid, cricoid, and epiglottis, respectively) and is supported by the hyoid bone.
Name the following
- Cricothyroid ligament
- Thyroid Cartilage
- Cricoid cartilage
- Epiglottis
5 Corniculate Cartilage
6.Arytenoid Cartilage
Mention the paired cartilage of the larynx
arytenoid
corniculate
cuneiform
Mention the unpaired cartilages of the larynx
Epligottis
Thyroid
Cricoid
Mention the Intrinsic muscle of the larynx
Cricothyroid
Thyroarytenoid
Vocalis
Posterior Cricoarythenoid
Lateral Cricoarytenoid
Transverse Arytenoid
Aryepiglottic
Oblique Arytenoid
Which muscle tension and elongates the vocal cords?
The cricothyroid muscle
Which muscle relaxes the vocal cords?
The thyroarytenoid muscle and the vocalis muscle
Which muscle abducts the vocal cords?
the posterior cricoarytenoid muscle
Which muscle adducts the vocal cords?
the lateral cricoarytenoid and the transverse arytenoid
Which muscle closes the glottis?
the aryepiglottic and the oblique arytenoid*
Which muscle closes the glottis and approximates the folds?
the oblique arytenoid muscle
Which muscles of the larynx are innervated by the recurrent laryngeal nerve?
All the muscles of the larynx are innervated by the recurrent laryngeal nerve except for the cricothyroid muscle
The crycorthyroid muscle is innervated by
the superior laryngeal nerve
Mention the extrinsic muscles of the larynx
sternohyoid
sternothyroid
thyrohyoid
thyroepiglottic
stylopharyngeus
inferior pharyngeal constrictor
What is the function of the sternohyoid muscle? Innervation?
Draws the hyoid bone inferiorly
Innervated by Cervical plexus, C1,C2,C3
What is the function of the sternothyroid muscle? Innervation?
Draws the thyroid cartilage caudad
Innervated by Cervical plexus, C1,C2,C3
What is the function of the thyrohyoid muscle? Innervation?
pulls the hyoid bone inferiorly
Innervated by cervical plexus, hypoglossal nerve and c1 and c2
What is the function of the thyroepiglottic muscle? Innervation?
Inversion of aryepliglottic fold
Innervated by RLN
What is the function of the stylopharyngeus? Innervation?
folds the thyroid cartilage
Innervated by glossopharyngeal nerve
What is the function of the inferior pharyngeal constrictor? Innervation?
aids swallowing
Innervated by pharyngeal plexus and vagus nerve
Why anticholinergic drugs are used during ENT procedures?
Anticholinergic drugs are used for their antisialagogue effect as its useful in certain intraoral procedures that require a drier operative field
Basically to decrease secretion
Which anticholinergic drug is best to use during an ENT procedure?
Glycopyrrolate as it produces less tachycardia in comparison with atropine
Also, Glycopyrrolate does not cross the blood-brain barrier and thus lacks of sedative effects
Important facts about Cocaine when used as a topical drug
concentration 4%
Dose 3mg/kg
Only anesthetic with vasoconstrictive ability
Blocks reuptake of norepi and epi at adrenergic nerve endings
Important facts about Benzocaine
Used for endoscopy
Short DOA (10 min)
Can produce METHOHEMOGLOBINEMIA
Bupivacaine Notable features
slow hepatic clearance long DOA
Dyclonine notable features
Topical spray or gargles
frequent use for laryngoscopy
absorbed through skin and mucous membrane
Hypotension technique: What are the disadvantages of sodium nitroprusside?
Reflex tachycardia
rebound hypertension
pulmonary shunting
possible cyanide toxicity
Hypotension technique: What are the disadvantages of dexmedetomidine?
Bradycardia, hypotension most often seen with bolus, heart block
Hypotension technique: What are the disadvantages of Nitroglycerin?
Increases intracranial pressure, highly variable dose requirements
Hypotension technique: What are the advantages of nicardipine?
preserves cerebral blood flow
Hypotension technique: What are the disadvantages of remifentanil with propofol?
No analgesic effect once remifentanil infusion is discontinued, post-operative secondary hyperanalgesia
Hypotension technique: What are the disadvantages and advantages of esmolol?
Advantages: particularly useful to control tachycardia
Disadvantages: Potential for significant cardiac depression
Hypotension technique: What are the advantages of nitroglycerin?
preserves myocardial blood flow
reduces preload
preserves tissue oxygenation
What are the specific concerns for laser safety?
eye protection with appropriate colored glasses
avoidance of the dispersion of noxious fumes
fire prevention
What stray or reflected beams of the ND:YAG laser can do to the eye?
tray or reflected beams of the ND:YAG laser can transverse the eye to the retina
During the use of Nd:YAG laser what type of eye protection is mandatory?
Green-lensed eye protection
What is the required protective eyewear for CO2 lasers?
Any clear glass or plastic that surrounds the face
What type of eye protection is required for potassium titanyl-phosphate (KTP) laser?
Orange-red eye protection
What type of eye protection is required for argon laser?
Orange glasses
Where is the thyroid located?
The thyroid is located on the anterioir and anterolateral aspect os the trachea immediately inferior to the larynx
The thyroid major blood supply arises from
The superior and inferior thyroid arteries which are branches of the common carotid artery
Identify the following
- thyro
Thyroid surgery pre-op assessment primary goal
ensure that the patient is euthyroid
Assess the degree of end-organ complications
determine the extent of airway involvement
Thyroid surgery Pre-op important keys
patient should continue their regimen of antithyroid medications and b blockade through the morning of the surgery
Patients with hyperthyroidism have an increased _______ and ______ values and a ______ or ________ thyroid stimulating hormone (TSH) levels
Patients with hyperthyroidism have increased T3 and T4 values and decreased or normal thyroid-stimulating hormone (TSH) levels
In what position the patient is placed during assessment of patient’s airway?
Supine position
During preop assessment for thyroid surgery what is done if there is any indication of potential airway compromise?
a chest radiograph and a CT scan of the neck and chest should be performed and evaluated prior to induction of anesthesia.
Patients with ______________have a higher incidence of myasthenia gravis and may present with skeletal
muscle weakness and an increased sensitivity to muscle relaxants.
Patients with hyperthyroidism have a higher incidence of myasthenia gravis and may present with skeletal
muscle weakness and an increased sensitivity to muscle relaxants.
What is the anesthetic technique of choice for thyroidectomy?
General endotracheal anesthesia is the technique of choice for thyroidectomy, and the standard induction and maintenance drugs are used.
Neuromuscular blockers and nerve testing during thyroid surgery
Paralysis may inhibit the surgeon’s ability to assess the integrity of the RLN, and relaxation is avoided after intubation if nerve testing is planned. Succinylcholine is chosen for intubation because of its short duration and spontaneous degradation.
What is the gold standard of visual nerve identification during thyroid and parathyroid surgery?
Intraoperative neural monitoring (IONM) during thyroid and parathyroid surgery has gained widespread acceptance as an adjunct to the gold standard of visual nerve identification
What is used to assess recurrent laryngeal and vocal cord function during thyroid surgery?
A special ETT, the Medtronic nerve integrity monitor (NIM) EMG endotracheal tube (NIM 3.0 ETT), is frequently used to assess recurrent laryngeal and vocal cord function during surgery.
The NIM 3.0 ETT
flexible silicone elastomer ETT with an inflatable cuff.
The tube is fitted with four stainless-steel wire electrodes (two pairs) that are embedded in the silicone of the main shaft of the ETT
The NIM 3.0 ETT electrodes
The electrodes are designed to make contact with the patient’s right and left vocal cords to facilitate EMG
monitoring of the muscles innervated by the RLN when connected to a four-channel EMG monitoring device
The red wire pair: anterior and posterior portion of the right true vocal cord,
The blue wire pair : anterior and posterior portion of the left true vocal cord.
Maintenance of anesthesia for thyroid surgery
Inhalational anesthetics can provide maintenance of anesthesia with or without N2O.
A combined deep and superficial cervical plexus block may be considered for intraoperative and postoperative pain management; additionally, IV anesthesia may also be suitable and provide optimal conditions.
Patient position for thyroid surgery
supine with the head elevated 30 degrees and the neck extended using a roll behind the neck and shoulders (Rose position).
- The arms are tucked at the patient’s sides with the ulnar nerves padded and protected.
Hyperextension of the neck should be avoided in those patients with atlantoaxial joint instability and/or those with limited range of motion.
If true hypotension occurs, it is best treated with a direct-acting vasopressor ____________ rather than an indirect-acting vasopressor ___________ which stimulates the release of catecholamines.
If true hypotension occurs, it is best treated with a direct-acting vasopressor (phenylephrine) rather than an indirect-acting vasopressor (ephedrine), which stimulates the release of catecholamines.
Complications associated with thyroidectomy
Postoperative hypocalcemia can result from
hypoparathyroidism
Symptoms associated with hypocalcemia develop
24 to 96 hrs postoperatively
Symptoms of hypocalcemia
perioral numbness and tingling
abdominal pain
paresthesias of extremities
carpopedoral spasm
tetany
laryngospasm
mental status change
seizures
What cardiac arrhythmia hypocalcemia can cause?
Q-T Prolongation and cardiac arrest
The following arrythmia can manifest with
Hypocalcemia
Neuromuscular irritability can be confirmig by assessing
Chovstek sign and Trousseau sign
Chvostek sign
facial contractions elicited by tapping the facial nerve in the periauricular area.
Trousseau sign
carpal spasm on inflation of a blood pressure cuff.
What is the treatment for severe symptomatic hypocalcemia?
administration of calcium gluconate or calcium chloride (10 mL of 10% solution) intravenously given over several minutes and followed by a continuous infusion (1–2 mg/kg/hr) until calcium levels normalize.
Unilateral RLN damage causes
The ipsilateral vocal cord to remain midline during inspiration resulting in hoarseness.
Unlike unilateral nerve injury, bilateral nerve injury necessitates immediate intervention requiring emergent reintubation or tracheotomy
During neck surgery postoperative bleeding of the surgical site results in a _________, which causes _________ and________. This complication represents a true surgical emergency.
postoperative bleeding of the surgical site results in a neck hematoma, which causes airway obstruction and asphyxiation. This complication represents a true surgical emergency.
Common symptoms of neck hematoma include
neck swelling, neck pain and pressure, dyspnea, and stridor.
Types of Le fort Fractures
The three types of Le Fort fractures, which describe a pattern of fractures involving multiple facial bones, are divided into Le Fort I, II, and III.
Le Fort I fracture
a horizontal fracture of the maxilla extending from the floor of the nose and hard palate, through the nasal septum, and through the pterygoid plates posteriorly. The palate, maxillary alveolar bone, lower pterygoid plate, and part of the palatine bone are all mobilized.
Le Fort II fracture
Le Fort II fracture is a triangular fracture running from the bridge of the nose, through the medial and inferior wall of the orbit, beneath the zygoma, and through the lateral wall of the maxilla and the pterygoid plates.
Le Fort III fracture
totally separates the midfacial skeleton from the cranial base, traversing the root of the nose, the ethmoid bone, the eye orbits, and the sphenopalatine fossa.
Which type of fracture is this?
Le Fort III
Which type of fracture is this?
Le Fort I
Which type of fracture is this?
Le Fort II
The patient with which type of Le Fort fracture causes little difficulty?
A Le Fort I fracture generally causes little difficulty for the anesthesia provider. Patients may be intubated orally or nasally, and the airway secured without a problem.
The Le Fort II and III fractures are of particular concern when contemplating nasal intubation because
disruption of the cribriform plate may occur, opening the underside of the cranial cavity.
What s/s can lead to inadvertent ETT or NG tube intracranial placement?
The presence of cerebral fluid in the nose, blood behind a tympanic membrane, periorbital edema, or “raccoon-eyes” hematoma are indications that attempts to pass an ETT or nasogastric tube through the nares could lead to inadvertent intracranial placement.
