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Where does the larynx lie in the cervical vertebrae?
- It lies in the anterior neck, at the level of C3-C6 vertebrae
- Adult C4-6 & child C3-5
The laryngeal skeleton consists of _______ cartilages joined by ligaments and membranes
Describe the blood supply to the larynx
- Arterial supply comes from the subclavian artery to the inferior thyroid artery to the inferior laryngeal artery
- Venous drainage to the inferior laryngeal vein from there to the brachial cephalic vein and from there to the SVC.
Which cartilages are single and which are paired?
- 3 single cartilages: thyroid, cricoid & epiglottic
- 3 paired: arytenoids, corniculate, and the cuneiform.
Is the hyoid bone part of the larynx?
NO, Hyoid bone is connected to but not part of the larynx.
The largest cartilage is also called the Adam's apple, which one is this?
- The thyroid cartilage is the largest of the laryngeal cartilages and the inferior 2/3 of the thyroid cartilage is that plate like laminae that fuse anteriorly and this is what forms the laryngeal prominence (aka Adams apple)
- The V shaped superior thyroid notch (thyroid notch) is above the laryngeal prominence
Describe the cricoid cartilage
Cricoid cartilage is shaped like a signet ring, band facing anteriorly and is much smaller than thyroid cartilage but it is also thicker and stronger and only complete ring of cartilage to encircle any part of the airway, narrowest part of airway in pediatric patients
Where is the larynx most accessible (closest to the skin)?
The cricothyroid ligament can be felt as the soft spot on the neck inferior to the thyroid cartilage, this is where the larynx is closest to skin and most accessible
How does the rima glottis look in ordinary breathing?
During ordinary breathing the opening is narrow and wedge shaped.
How does the rima glottis look in forced respiration?
it’s wide and kite shaped
How does the rima glottis look during phonation?
the vocal cords are closely approximated so the rima is slit like.
How does the voice change pitch?
The voice will change in pitch according to the tension and length of the vocal cords, the width of the rima glottis and the intensity of the expiratory effort
What are 3 functions of the larynx
- Protection of the airway
How does the larynx protect the airway?
- Primarily a reflex & involuntary process
- Glottis closes by a reflex activated by swallowing
- A primitive reflex elicited by stimulation of the superior laryngeal nerve
The extrinsic laryngeal muscles will move the larynx as a whole. How many extrinsic muscle are there? How many groups and what do they do?
- There are 8 extrinsic muscles that get divided into 2 groups.
- 1 group will depress the hyoid and larynx. These are the infrahyoid muscles.
- The other group will elevate the hyoid and the larynx, these are suprahyoid and stylopharyngeal muscles.
What do the intrinsic muscles do?
- The intrinsic muscles in contrast will move the laryngeal parts and so they’ll make changes in the length and the tension of the vocal cords, and therefore the size and the shape of the opening that rima glottis (between the cords).
- So they essentially serve the 3 functions: they’ll open vocal cords during inspiration and they’ll close the vocal cords during swallowing, and they’ll change the tension of the vocal cords during speech.
So the intrinsic muscles can be grouped according to their actions, what are the groups?
- First group is the adductors (towards the midline) and abductors (away from midline).
- Second group are the sphincters
- Third group are the tensors
- Fourth group the relaxers.
ALL BUT ONE OF THE INTRINSIC MUSCLES OF THE LARYNX ARE SUPPLIED BY THE RECURRENT LARYNGEAL NERVES, what is the exception?
cricothryoid is innervated by the external laryngeal nerve
What is the recurrent laryngeal nerve a branch of?
The other intrinsic muscles of the larynx are supplied by the recurrent laryngeal nerve which is a branch of the 10th cranial nerve (vagus).
What is the external laryngeal nerve a branch of?
The external laryngeal nerve is one of two terminal branches of the superior laryngeal nerve.
What is the main action of the cricothyroid muscles?
- Cricothyroid muscles are the principle tensors, they’ll tilt or pull the angle of the thyroid cartilage anteriorly and inferiorly toward the arch of the cricoid cartilage.
- So they tense and elongate the vocal cords. As the vocal ligaments will elongate and tighten that will raise the pitch of the voice.
What is the main action of the posterior cricoarytenoid muscles?
- The posterior cricoarytenoid muscles are the only Abductors.
- Ultimately what happens when they contract is they’ll widen the rimaglottis, opening the vocal cords. They move the arytenoids outward
What is the main action of the lateral cricoarytenoid muscles?
The lateral cricoarytenoid muscles, the principle adductors, so they’ll close the vocal cords.
What muscles do the transverse arytenoid muscles work with? What do they do?
- lateral cricoarytenoid muscles, together the transverse arytenoid muscles, they’ll pull the arytenoids together.
- This is when air gets pushed through the rima causing vibrations of the local ligaments and causing phonation.
- The transverse arytenoids are also adductors and so we can think of the transverse arytenoids and the lateral cricoarytenoid muscles as working together.
What do the thyroarytenoid muscles do?
- The thyroarytenoid muscles are the principle relaxers.
- They’ll pull the arytenoid cartilages anteriorly toward the thyroid prominence and that will relax the vocal cords.
- This will lower the voice
So the vagus nerve (CN X) supplies the larynx, what are the two branches of this nerve that supply the larynx
Superior laryngeal nerve & the recurrent laryngeal nerve
There are two branches of the superior laryngeal nerve? What does this nerve supply?
- The superior laryngeal nerve is divided into the internal branch and the external branch.
- The superior laryngeal nerve supplies sensory innervation of the larynx down to the vocal cords
What does the internal branch of the superior laryngeal nerve supply?
The internal branch is mainly sensory with few motor fibers leading to the arytenoid muscles.
What does the external branch of the superior laryngeal nerve supply?
- The external branch of the superior laryngeal branch is motor and it innervates the cricothyroid muscle and the inferior pharyngeal muscle.
- Again the cricoid muscle is the only intrinsic laryngeal muscle not innervated by the recurrent laryngeal nerve.
What does the recurrent laryngeal nerve innervate?
So recurrent laryngeal nerve will innervate all other intrinsic muscles other than the cricothryoid and it provides sensory innervation to the larynx below the vocal cords
So the vagus has two branches (recurrent laryngeal nerve and the superior laryngeal nerve) that supply the intrinsic muscles. What supplies the extrinsic muscles?
The extrinsic muscles are innervated by the cervical plexus C1-3.
The recurrent laryngeal nerve can be injured by endotracheal intubation, neck surgery, or even stretching of the neck during surgery. What is the result of this injury?
The resulting tone and position of the vocal cords will depend on whether the external branch of the superior laryngeal nerve (again motor innervation of the cricothryoid muscles leading to short vocal cords) is also involved
What is the unilateral recurrent laryngeal nerve injury?
- Unilateral recurrent laryngeal nerve injury will cause the cord on injured side to assume a paramedian position.
- The voice then, as a result of unilateral recurrent laryngeal nerve injury, will be a weakened voice and an increased risk of aspiration.
What happens if there is bilateral damage to the recurrent laryngeal nerve from ischemia?
In the case of bilateral damage from ischemia, there is a complete airway obstruction because of laryngospasm.
What happens if there is bilateral damage to the recurrent nerve from transection?
If however the nerve is transected bilaterally, the vocal cords will be flaccid, but there may be some air passage.
Which nerve is implicated in laryngospasm?
So laryngospasm is due to spasm of the glottic muscles and it’s mediated by the superior laryngeal nerve.
What are the external landmarks of the larynx and the cricoid?
- So the vocal cords are at the level of the middle of the laryngeal prominence.
- The cricoid is an important landmark, it’s felt inferior to the laryngeal prominence at the level of the C6 vertebrae
The cricoid is a key landmark for us, what does it indicate to us?
- Level of C6
- It’s the site where the carotid artery can be compressed against the transverse processes of C6
- It’s the junction of the larynx and the trachea
- It's where the pharynx and the esophagus join
- It’s the point where the recurrent laryngeal nerve will enter the larynx
- It’s the site that’s approximately 3cm superior to the isthmus of the thyroid gland, It’s the narrowest part of the airway in the pediatric patient.
Where is the cricoid in relation to the thyroid gland?
approximately 3cm superior to the isthmus of the thyroid gland
Why can't we feel the 2-4th tracheal rings but we can feel the 1st?
The tracheal rings are palpable in the inferior part of the neck but the 2nd through the 4th cartilaginous rings can’t be felt because that’s where the isthmus of the thyroid is.
The pharynx can be divided into 3 parts, what are they?
- The nasopharynx (posterior to the nose and superior to the soft palate)
- The oropharynx (posterior to the mouth)
- The laryngopharynx (posterior to the larynx)
In only about __% of microsurgical procedures on the larynx does the pathology involve the lower 1/3 of the vocal cords of the posterior commissure
What size ETT should we use for microlaryngoscopy?
- So for most cases a small ETT (Miller says 5.5 to 6.0).
- Is usually adequate for oxygenation and ventilation but if need be can go probably to a size 4.5 or a 5.0. so that the surgeon can see what he/she is doing w/out the tube getting in the way.
- And of course we need to balance the surgeons goals with ours, the surgeon wants the clear view with room to work and prefers a small ETT. Most ENT surgeons would like the smallest tube that you’ll be willing to place but they will ultimately let the decision be ours.
What medication might we give pre-op to control secretions?
In general, the apnea technique is not commonly used for ENT surgery, but how is this done?
- There is alternating ventilation with surgical excision and no tube during the removal of the lesion.
- Maintain adequate depth of anesthesia with TIVA.
- Allow the surgeon to have the airway and resect the lesion watching the oxygen saturation when it drops to a point that we feel like we need to ventilate the patient then we’re mask ventilating the patient until the O2 Sat comes up and then again letting the surgeon go back to surgical excision.
- So alternating surgical excision with essentially a mask airway.
The incidence of an MI or ischemia after microlaryngsoscopy has been reported to be 1-____-___%
What type of ventilation during laryngoscopy uses the Venturi effect?
JET ventilation which takes advantage of the venturi effect
When considering JET ventilation, what types of things do we need in order for it to work?
- With this method the laryngoscope you have here aligns with the axis of the trachea by the surgeon, the vocal cords must be completely relaxed and the pathology must not be so large to obstruct the airflow into the trachea.
- Also important is the JETed gas must be allowed to exit freely and we actually monitor that by looking at chest wall excursion.
During JET ventilation, what are the pressures, how long does inspiration and expiration last and how quick is the RR?
Ventilation with JET ventilation begins with pressures of about 30-55psi, inspiration will last for about 1.5seconds and passive expiration about 6 seconds so the respiratory rate is abut 6-7 breaths/min
When is JET ventilation contraindicated?
This technique is contraindicated in children, obese patients, and anyone with emphysematous bullae.
Why don't we know the true FiO2 when using JET ventilation?
- Venturi effect where there is entrainment of ambient gas in a ratio of about 2-3:1.
- So that results in a TV that’s greater than the JET volume but naturally a variable gas composition so typically we have 100% oxygen that we’re using but room air is getting entrained so we really don’t know what the FiO2 is.
What is the major concern with JET ventilation?
concerns with JET ventilation because of high pressures would be barotrauma
What does LASER stand for?
Light Amplification by Simulated Emission of Radiation
What decides what TYPE of laser is used? (in general)
Various types depending on the emission medium used.
What are the modes a laser can be used in?
Lasers can be used in short pulses, long pulses or in a continuous mode
What does YAG stand for?
YAG laser, stands for neodymiumdoped aluminum garnet (Nd:YAG).
what is the most widely used laser?
the CO2 laser
What is the wavelength of the CO2 laser?
It produces radiation w/a wavelength of 0.01mm.
CO2 laser is very suitable for removing lesions of the vocal cords and the larynx, how does it do this?
What happens is the laser energy is absorbed by the water in the tissue that increases the temperature which denatures the protein, vaporizing the target tissue.
Why is the YAG laser used for detached retinas?
- The YAG and the argon laser absorbed preferentially by hemoglobin and pigmented tissue have deep penetrating effects.
- So for that reason they get used with detached retinas, the variant of this
We must use eye protection during laser surgery, what hurts the cornea and what hurts the retina?
The CO2 will react to the surface of the eye and cause corneal abrasion but the YAG has a shorter wave length and it can pass through and damage the retina
Why are Polyvinyl fluoride tubes not ideal for airway surgery?
Polyvinyl fluoride tubes will burn pretty quickly, and will also produce hydrogen chloride which is a pulmonary toxin
What do we do to the ETT cuff for airway surgery?
So some of the strategies that we employ, we fill the cuffs with sterile saline and methylene blue that way if the cuff were to break we would know that because the methylene blue and the saline would hopefully put out any fire
What FiO2 do we use for airway surgery? Can we use N2O?
- We want to not use any more than 30% oxygen and nitrogen or air, so typically we turn it to as close to RA as we possibly can.
- N2O does support combustion so you don’t want to use that.
What is the treatment for an airway fire?
- The treatment of an airway fire means discontinuing the oxygen, remove the ETT, reintubating the trachea, flushing the pharynx with cold NS, and then a rigid bronchoscope should be used to check for damage, presence of foreign bodies like remnants of the burned ETT and then depending on the situation.
- Other treatment might be involved, humidified gas, steroids, and antibiotics.
The nasal mucosa has a rich blood supply and so pre-op we’re doing our assessment what do we want to verify ?
that any anticoagulants have been d/c’d
What might an ENT surgeon be led to do to minimize blood loss?
The surgeon will likely be led to do thing intra-op to minimize blood loss, include these potent packing and/or local anesthetic solutions containing epinephrine infection into the operative area
What is the max dose of Procaine? When does it peak?
- Maximum dose is 3mg/kg
- is rapidly absorbed and peaks in about 30min
Why might we see adverse CV effects from the local anesthetic?
- inhibits the reuptake of norepinephrine. So it will potentiate the effects of adrenergic stimulation.
- The CV response that’s frequently seen is HTN, ventricular atopic activity
Besides pharmacologic techniques, what else can we do to minimize blood loss?
Another strategy is to maintain ahead up position of about 15 degrees. That can also help give the surgeon some controlled hypotension.
Corneal abrasion is always a risk during surgery of the head and neck so the eyes must be taped closed. What is the exception to this?
The exception during that rule though is during FESS (Functional endoscopic sinus surgery) because the surgeon may want to periodically check for eye movement during dissection because the close proximity of the sinuses
What does Barash say about TIVA vs GA for endoscopic sinus surgery?
TIVA with Remi and propofol in general yields better visualization and decreased blood loss and also the patient is less likely to cough on emergence and less likely to have PONV
What must we balance during emergence of an ENT surgical patient?
On emergence we need to balance the desire for minimal coughing and bucking with the risk of pulmonary aspiration of blood in the setting of depressed airway refllexes
Paranasal sinuses are air filled extensions of the respiratory part of the nasal cavity. So the sinuses get named according to the bones they are located. Name these sinuses
the frontal, ethmoid, sphenoid, & maxillary cranial bones
There is a thin area separating the sphenoid sinuses from them several important things, name these things.
optic nerve the pituitary gland, internal carotid arteries and the cavernous sinuses.
With FESS, there is about a 1% incidence of major complications which can include ..........
orbital hematoma, blindness, diplopllia, CSF leak, CNS infection, stroke, carotid artery injury and death
With FESS, there is ~5% incidence of minor complications which includes.......
periorbital emphysema, ecchymosis, lip pain or numbness, bronchospasm and epistaxis.
Naturally in order to access the operative ear the head has to be turned to one side but we don’t want to have too much of an extreme of neck extension or torsion, otherwise, what can happen?
- Injury to the brachial plexus from stretching or injury to the cervical spine.
- Also if the patient has limited carotid artery flow because of stenosis, they are particularly vulnerable to further decreases in flow from exaggerated neck positioning
N2O that it’s ___x more soluble in blood than nitrogen
The middle ear and the paranasal sinuses are normal air filled cavities that consist of open non ventilated spaces, how does it vent?
The middle ear is vented intermittently when the Eustachian tube opens
At what pressure do the Eustachian tubes usually vent?
What happens when N2O is used?
- Normally the Eustachian tube will passively vent at a pressure of about 200-300 mmH2O.
- But middle ear pressures can reach 375mmH2O within 5-30min of the start of N2O.
- And that exceeds the ability of the Eustachian tube to vent.
Nitrous can actually be hazardous to patients who have had previous reconstructive ear surgery and so according to Barash it should be avoided up to ___weeks post-op
What kinds of injury to the ear could the use of N2O lead to?
- The use of N2O could lead to the development of serous otitis, disarticulation of the stapes and impaired hearing.
- N2O can also cause an increase in N/V. And can lead to rupture of the tympanic membrane with elevated middle ear pressure, Eustachian tube malfunction.
With tympanoplasty surgery nitrous should be limited to __% if used at all and discontinued and discontinued __mins prior to closure of the middle ear and tympanic membrane
Otologic surgeries are associated with up to ___% incidence of facial nerve paralysis
Describe the anatomic make up of the thyroid gland
- Anatomically the thyroid gland consists of 2 lobes connected by a bridge of tissues called the thyroid isthmus as you can see here.
- The gland is very vascular its innervated by the autonomic nervous system and it consists of multiple follicles filled with colloid.
- The colloid is primarily thyroglobulin the thyroid hormones are stored in combination with the thyroglobulin
Why is it so important to know WHY the patient is having a thyroidectomy?
- Medullary thyroid cancers associated with multiple endocrine neoplasia (MENS) and that means the patient may have an undiagnosed pheochromocytoma.
- The catecholamine surge from the pheo could mimic thyroid storm and vice versa so better to know from the start what your dealing with.
epinephrine and thyroxine are derivatives from the amino acid ________ so you will get the same effect of sympathetic stimulation of hyperthyoidism.
What must we ensure prior to thyroid surgery?
- It’s important to know they have been rendered euthyroid prior to surgery and you remember this is often accomplished pre-op with lugals iodine solution.
- Surgeon will want to be certain the patient has been compliant with the medication. Surgery will be cancelled if the patient has not been taking the iodine solution.
Pre-op assessment for thyroid surgery is AIRWAY! what are we looking for?
- Tracheal deviation
- Tracheal ring involvement
- Inflammation due to thyroiditis
We check TFTs to ensure the patient is euthryoid, and we look at the resting HR, what does this tell us???
- Resting heart rate < 85
- Will ↓ risk of thyroid storm by >90%
The incidence of permanent RLN injury in thyroid surgery is anywhere from up to __% so for this reason, some sort of nerve monitoring is used by the surgeon.
During thyroid surgery, the surgeon may want to limit NMB and use a NIM tube. What is the NIM tube useful for?
NIM is an ETT based electrode system that creates both passive and evoked EMG monitoring of the left and right thyro-arytenoid muscles during thyroid surgery
What is important to know about the positioning of a patient during a thyroidectomy?
- Beach chair, HOB is raised about 15-20 degrees.
- Increased risk for venous air embolism.
- Because the surgeon is working on the neck, arms are tucked at side, often a towel or some other positioning device will be placed behind the patients upper back to aide in exposure.
- Also want the HOB to be clipped back.
Why is eye protection so important during a thyroidectomy?
- Eye protection is particularly important d/t the close proximity to the surgical field, assistants may lean on the face.
- Also the patient may have exopthalamus and that will put them at increased risk for corneal abrasion and laceration.
What drugs should we avoid during a thyroidectomy?
avoid Ketamine,Pavulon (pancuronium), & potentially indirect acting adrenergic agonist again this depends on the situation.
Why is the hyperthyroid patient prone to liver/kidney issues?
Hyperthyroid patients have accelerated biotransformation so theoretically may be more susceptible to hepatic injury from drugs that are metabolized to metabolites could result in damage to the kidney
NMB you wouldn’t really use for reasons just said but if for some reason you were using it. Use cautiously in a thyroidectomy, why?
- because of the increased incidence of myopathy and myasthenia gravis in patients with thyrotoxicosis.
- That really applies for patients who are having emergent surgery
Hyperthyroidism itself doesn’t increase anesthesia requirements but why might they change?
increase in CO
How might the surgeon avoid tetany post-op thyroidectomy?
preserve the parathyroid to avoid any tetany post-op
The incidence of bleeding following tonsillectomy that requires re-operations is up to about 0.5%.
What is the timing of bleeding post-op tonsillectomy?
The timing is usually within the first 6hrs of surgery but the bleeding can occur until the 6th POD.
What are our concerns with a peritonsillar abscess
- Respiratory obstruction so the risk of anesthesia include further obstruction plus a difficult intubation as a result of continued trismus distorting the anatomy and spontaneous rupture of the abscess.
- Management includes careful intubation to avoid the abscess and may want to consider the possibility of an awake intubation.
- And possible maintenance of spontaneous respiration with mask induction or an elective trach
What is ludwig's angina?
- cellulitis of the submandibular and sublingual spaces that may include the floor of the mouth and the anterior neck
- It’s often impossible to visualize the glottic opening because of trismus edema and distortion.
For Ludwig's angina, when is GA contraindicated? What might we have to do even if it isn't ideal?
GA is contraindicated if there is stridor at rest. A tracheostomy through the cellulitis although not ideal may be the best choice.
What is epiglottitis?
bacterial infection, progresses rapidly from a sore throat to dysphagia and then complete airway obstruction
What is the more accurate term for epiglottitis?
Supraglottitis may be a more accurate term because the inflammation typically involves all supraglottic structures
Epiglottitis can occur in kids or adults. What age group of kids and how often in adults?
- Kids it will classically affect ages 2-6.
- But it does occur in 1 out of 100,000 adults every year.
What are the symptoms of epiglottitis?
Symptoms would include sore throat, dysphagia, that muffled hot potato voice (sounds like someone has a hot potato in their mouth) and respiratory distress
What imaging might we want to get for epiglottitis?
A pre-op lateral neck X ray may show a characteristic thumb like epiglottic shadow. Which if present, is very specific that it is often absent. The Xray may often be useful because it may show another cause of the obstruction like a foreign body.
How can you tell there is an impending airway obstruction in epiglottitis?
Symptoms would include stridor, drooling, hoarseness, again a really rapid onset and progression, tachypnea, chest retractions and preference for sitting in an upright position
So you're patient with epiglottitis is brought to the OR for intubation, what must you have available?
Because complete obstruction can occur at any time, a trach set must be set up prior to induction because if you can’t intubate the patient, either a rigid bronch or a trach must be preformed, the ENT surgeon must be present in the OR.
What is the technique for epiglottitis?
- The technique for a patient with epiglottitis is a careful inhalation induction, don’t want to manipulate the airway in an attempt to intubate the patient prior to inducing anesthesia.
- Want to keep the patient spontaneously breathing but deep.
- Laryngoscopy is then performed and the only way you may know to place the ETT is by the air bubbles that are leaking from the trachea so you really often may not be able to see any anatomy, just see these air bubbles escaping from the trachea and place the tube there.
What is croup??? How is it different than epiglottitis?
- Croup is obstruction of the airway that is characterized by a barking cough.
- Infectious croup usually follows and URI that’s viral in kids 3M-3yrs.
- This involves the airway below the epiglottis so it’s called laryngeal tracheal bronchitis.
- In contrast to epiglottitis it progresses slowly and rarely requires intubation.
How would we do induction for a foreign body aspiration?
A gentle mask induction w/out cricoid pressure or PPV is preferred
What is the post-op care for foreign body aspiration?
- Laryngeal and subglottic edema can last for 24hrs after the foreign body is removed.
- And then close observation with humidified oxygen are really (or rarely) needed
- Reaction caused by the obstructing material such as peanut oil from aspirating a peanut.
For the nasal surgery, nasal mucosa cotton pledgets on long applicators are soaked in what? And then how is it applied to the nasal mucosa?
- Get soaked in the 4% cocaine or a mixture of lidocaine with phenylephrine.
- Inserted gently into the nare.
- 1st applicator gets inserted directly posterior along the inferior turbinate to the posterior pharyngeal wall.
- 2nd applicator is then inserted with a slightly cephalad angle to follow the middle turbinate and again advanced to it’s full depth until it touches the mucosa over the sphenoid
For nasal surgery, why do we preform the local anesthesia bilaterally? How long does it take to kick in?
- Anesthesia is performed bilaterally because the objective is to provide anesthesia of the branches of the sphenopalatine ganglion, as well as topical anesthesia of the mucosa itself.
- 2-3 min of contact time is usually required
How are the mucous membranes innervated?
- Anteriorly: innervated by the ophthalmic divisions of the trigeminal nerve
- Posteriorly: by the maxillary division posteriorly
The lower branch of the superior laryngeal nerve passes close under the surface of the mucosa of the______________ supplying the ________ innervation to the arytenal epiglottic folds and the posterior rima glottis.
The lower branch of the superior laryngeal nerve passes close under the surface of the mucosa of the pyriform form fossa supplying the sensory innervation to the arytenal epiglottic folds and the posterior rima glottis.
For a superior laryngeal nerve block there can be either a topical or an external approach. What is the topical approach?
The topical is the simplest method and that is to apply local anesthetic for 3-5min onto the pyriform form fossa mucosa.
What are the anatomic landmarks for the external approach for a superior laryngeal nerve block?
The hyoid bone, the thyroid cartilage and the thyrohyoid membrane
Describe how to perform the external approach for a superior laryngeal nerve block
- The procedure is that the head is extended the thyroid cartilage and hyoid bone are identified.
- The index finger retracts the skin down over the superior thyroid cartilage, alcohol to skin, then introduce the 23 or 25G needle attached to a 5ml syringe that’s filled with 1-2% lidocaine.
- The needle is inserted onto the tip of the cartilage.
- Your index finger then releases that skin retraction and the needle gets walked off the cartilage superiorly and is inserted just through the firm thyrohyoid membrane. The tip of needle is now in the loose areolar tissue plane beneath the membrane, seen in figure.
- 1st aspirate to ensure not intravascular and then inject 2.5ml into the plane membrane and then repeat on the opposite side.
What areas will the external superior laryngeal nerve block anesthetize?
All laryngeal mucous membranes above the rima glottis including the epiglottis and the arytenoepiglottic folds.
In what patients should we use caution when performing a superior laryngeal nerve block?
- Because it removes some of the protective reflexes, this block should be used in caution with patients who are full stomach
- (also external approach is not used if there is an infection or tumor)
What does CN 9 innervate?
Glossopharyngeal nerve (CN 9) innervates the posterior 1/3 of the tongue, oropharynx, the tonsils, gag reflex
How can we perform the glossopharyngeal nerve block? Can this be used as a technique for intubation?
Can be blocked by 1 of 3 methods, either topical spray, direct application of soaked pledgets or infiltration, it is alone not adequate as a technique for intubation
What is one of the caveats of the glossopharyngeal nerve block?
One of the caveats is that it can cause some significant airway obstruction so if it’s used along with a superior laryngeal nerve block, the superior laryngeal nerve block should be preformed first to avoid respiratory obstruction
How do we perform the glossopharyngeal nerve block?
- Direct submucosal injection into the base of the anterior tonsillar pillar.
- After initial topical anesthesia, the tongue gets pulled over retracted medially with this tongue depressor that reveals the inferior curve of the anterior tonsillar pillar.
- A 25G spinal needle (it's longer and keeps syringe out of mouth) and 2ml of 1% Lidocaine is injected, 0.5cm below the mucosa at a point 0.5cm lateral to the base of the tongue.
- Aspirate to check for intravascular placement, bilateral injection is needle to block both lingual branches of the glossopharyngeal nerve.
Why is simple topical anesthesia better for a glossopharyngeal nerve block?
The risks of intravascular injection and the greater discomfort make simple topical anesthesia a better choice for most patients.
How do we perform a transtracheal injection?
- 20G angiocath is introduced through the cricothyroid membrane after previously injecting a small skin wheel, entry into the trachea is confirmed when you aspirate air, the stylet then gets removed and a syringe with 4% lidocaine gets attached to the angiocath that remains in the trachea.
- The Lidocaine is injected as you ask a patient to take a deep breath and the spray will cause the tissue to cough and that will spread the solution up the trachea to the level of the vocal cords.
What is the common dosage of cocaine used for airway anesethesia? (amount, concentration, total mgs, % max recommended dose)
- Amt: 3
- Conc: 4%
- Mgs: 120
- % max dose: 60
What is the common dosage of tetracaine used for airway anesethesia? (amount, concentration, total mgs, % max recommended dose)
- Amt: 5
- Conc: 1%
- Mgs: 50
- % max dose: 25
What is the common dosage of Lidocaine used for airway anesethesia? (amount, concentration, total mgs, % max recommended dose)
- Amt: 5; 4
- Conc: 1%; 4%
- Mgs: 50; 160
- % max dose: __; 40
What is the most likely cause of systemic toxicity?
Systemic toxicity is the most likely outcome it’s d/t absorption rather than IV injection
Although not all local anesthetic is absorbed the total amounts can cause systemic toxicity, so what should we do in case this happens?
For this reason resuscitation equipment always has to be ready, patient must be closely observed for the block and at least 20min after completion.
What is removed and what is preserved during a radical neck dissection?
- The deep cervical lymph nodes and the tissues around them are removed as much as possible.
- The major arteries, brachial plexus, CN 10, and phrenic nerve are preserved but most cutaneous branches of the cervical plexus are removed
What is your patient having a radical neck dissection likely to have in terms of co-morbidities?
- Patients here are often heavy cigarette smokers and often have a heavy alcohol consumption.
- So there will be associated co-morbidities, including COPD, CV disease, and often malnutrition, anemia, dehydration and electrolyte imbalances.
- These patients need to be evaluated and treated as difficult intubations
Do we always give NMB for radical neck dissection?
Non depolarizing MR are contraindicated because the surgeon will need to identify the nerves.
What are some surgical complications we should be aware of intra-op during a neck dissection?
Carotid sinus stimulation can cause bradycardia, hypotension and even cardiac arrest and because usually the patients head is elevated about 10-15 degrees, venous air embolism may also occur.
What type of anesthetic technique is utilized during a neck dissection?
- Volatile techniques as well as TIVA.
- The volatile agents will dilate the bronchi and depress airway reflexes and produce hypotension which may assist in managing blood loss.
- Usually an A-line is advisable and frequently a phenylephrine gtt is needed to support the BP so adequate analgesia and immobility can be assured.
What is a LeFort I fracture?
- A LeFort I fracture is a simple horizontal fracture of the lower maxilla.
- Just above the teeth and palate separating the maxilla from the palate producing essentially a mobile palate.
What is a LeFort II fracture?
- A LeFort II fracture crosses the nasal bones on the ascending processes of the maxilla and the lacrimal bone and crosses the medial and inferior orbital rims.
- Essentially a triangular extension of the LeFort 1 fracture.
- Sometimes called paramiddle.
- This fracture separates the maxilla from the face.
What is a LeFort III fracture?
- The LeFort III fracture is a high level transverse fracture that crosses the front of the maxilla and the lacrimal bone and through the orbits.
- The cribiform plate of the ethmoid may or may not be fractured.
- It’s characterized by complete separation of the maxilla from the cranial facial skeleton.
- There is often epitasis and a flat dysphagia deformity.
- Results from massive force being applied to midface
Significant to know that tears in the dura occur in ____% of all LeFort II and III fractures
LeFort II and III fracture can cause dural tears, so we may note leakage of CSF. What should we avoid in these patients?
Nasal intubation should be avoided in patients that have nasal, orbital, or zygomatic fractures essentially LeFort II and III because an ETT or a NG tube could migrate into the orbit, the base of the skull, or the cranium.
What should we keep in mind for facial/jaw surgery?
- As with dental surgery, throat pack is often used and with these patients the jaw will often be wired shut at the end.
- Wire cutters need to accompany the patient leaving the OR, want to assure that we give our anti-emetics because vomiting would be a problem with a wired jaw.
- Smooth emergence would be deisred to minimize bleeding which would complicate the problems with N/V.