Card Set Information
BC Nurse Anesthesia
Level of the larynx in the adult?
How many cartilages form the larynx?
Larynx arterial blood supply
subclavian artery to inferior thyroid artery to inferior laryngeal artery
Larynx venous blood drainage
inferior laryngeal vein to brachiocephalic vein to SVC
3 single cartilages of the larynx
epiglottic, thyroid, cricoid
3 paired cartilages of the larynx
arytenoids, corniculate, cuneiform
What forms the Adam's apple?
largest of the laryngeal cartilages
Attaches thyroid cartilage to the hyoid bone
Narrowest part of the pedi airway
Attaches cricoid cartilage to the thyroid ligament
First cartilage seen on DL
List the following structures from cephalad to caudad: cricotracheal ligament, thyroid cartilage, 1st tracheal ring, thyrohyoid membrane, cricoid cartilage, cricothyroid membrane, hyoid bone
1st tracheal ring
Where is a trach usually placed?
Mid way btw the thyroid notch and the suprasternal notch
A vertical incision is made thru the 2nd and 3rd tracheal rings with the thyroid isthmus divided and retracted
Narrowest part of adult airway
Position of the rims glottidis
resting= narrow and wedge shaped
forced respiration= wide and kite shaped
phonation= slit like as VC are closely approximated
opening btw the VC
What are the 3 functions of the larynx?
How does the larynx protect the airway?
Involuntary reflex function
glottis closes by a reflex activated by swallowing
primitive reflex elicited by stimulation of the superior laryngeal nerve
Function of the extrinsic laryngeal muscles
move the larynx as a whole
extrinsic laryngeal muscles
2 main groups?
infrahyoid and suprahyoid
function of the infra hyoid laryngeal muscles
depress hyoid and larynx
function of the supra hyoid laryngeal muscles
elevate hyoid and larynx
function of the intrinsic muscles of the larynx
move laryngeal parts
make changes in length and tension of the VC
open and close the glottis essentially
VC should be ____ during swallowing and ____ during inspiration
4 classifications of intrinsic laryngeal muscles
adductors and abductors
All but one of the _____ laryngeal muscles are supplied by the _____.
Only the ______ is innervated by the external laryngeal nerve. All the other intrinsic muscles are supplied by the ____.
The RLN is a branch of what CN?
10th CN, vagus
Major tensor intrinsic laryngeal muscles
tense and elongate the VC, this causes voice pitch to rise
Abductor intrinsic laryngeal muscle
open VC by widening the rims rims
Major adductor intrinsic laryngeal muscle
work with transverse arytenoid muscles
air gets pushed thru rims glottides to cause vibration of vocal ligaments and to cause phonation
The transverse arytenoid muscles cause
adduction, work with the lateral cricoarytenoid muscles
Thyroarytenoid muscle function
relax VC and lower the voice
intrinsic muscles that fall into the category of sphincters
What nerves supply the larynx?
Vagus, RNL, and superior LN
What is the only intrinsic laryngeal muscle NOT innervated by the RNL?
the cricothyroid muscle
What supplies sensory innervation of larynx down to the VC?
Internal branch of the superior LN
Function of the external branch of the superior laryngeal nerve
innervates cricothyroid muscle and inferior pharyngeal muscle
What nerve provides sensory innervation of the larynx below the VC?
Thyroid or parathyroid surgery has the potential to cause damage to what nerve?
Unilateral RLN injury
cord on the injured side will assume a paramedian position
hoarse and weak voice
increased risk of aspiration
What occurs with bilateral ischemia of the RLN?
Laryngospasm causing complete airway obstruction
What causes laryngospasm?
What nerve is involved
Spasm of glottic muscles
The VC are at the level of the?
cricoid cartilage is at the level of the ___ vertebra
Why is the cricoid cartilage an important landmark?
-site where carotid artery can be compressed against the transverse process of C6
-junction of larynx and trachea
-site where pharynx and esophagus join
-point where RLN enters larynx
-narrowest part of the pedi airway
3 parts of the pharynx
nasopharynx- posterior to nose and superior to soft palate
oropharynx- posterior to mouth
laryngopharynx- posterior to larynx
T or F, the pharynx extends from the base of the skull to below the level of the body of C6 where it becomes continuous with the esophagus
Anesthesia goals r/t microlaryngoscopy
Atraumatic intubation (minimize bleeding for surgical visualization)
Protect tracheal with cuffed ETT
Adequate oxygenation and ventilation (surgeon wants smallest ETT possible- as small as 4.5 mm)
Minimize secretions- glyco often requested, minimize coughing in response to secretions
Prompt wake up with return of protective reflexes
T or F, MR is typically NOT required for microlaryngoscopy
Why is microlaryngoscopy associated with 1.5-4% incidence of Mi or ischemia?
suspended laryngoscope is stimulating
can cause HTN, tachycardia, arrythmias
Possible techniques used to perform microlaryngoscopy
apneic- alternate mask ventilation with surgical incision, use TIVA
spontaneous breathing with deep anesthesia (tricky)
How does jet ventilation work?
Utilizes the Venturi effect, Bernouli's theory
VC must be relaxed
Jet gas must be allowed to exit freely
Use 100% O2, but air is entrained, so actual FiO2 < 100%
Contraindications / risks of jet ventilation
pedi, obesity, emphysematous bullae
light amplification by simulated emission of radiation
most commonly used laser
suitable for removing lesions on VC and larynx
produces radiation with a wavelength of 0.01 mm
YAG and ARGON laser
deep and penetrating effects
suitable for detached retinas
shorter wl than CO2 laser
Major anesthesia considerations r/t laser use
airway fire and eye protection (for all in room!!)
Strategies to avoid an airway fire
fill cuff with NS or methylene blue
avoid N20 (combustable)
FiO2 <= 30%
Steps to take if an airway fire does occur
First step = D/C O2
flush pharynx with cold NS
rigid broch to check for damage and presence of foreign bodies
possibly steroids, humidified gas, abx
T or F, the nasal mucosa has minimal blood supply
F, rich blood supply
considerations r/t pts undergoing nasal or sinus surgeries
pre-op nasal obstruction
nasal polyps are associated with asthma and CF
max dose of cocaine
3 mg / kg
SE of cocaine
HTN and ectopic ventricular activity
cocaine inhibits reuptake of NE
Why are the eyes not taped for FESS?
Surgeon may want to periodically check for eye movement during dissection due to close proximity of the sinuses and the orbit
Is TIVA or volatile anesthesia preferred for nasal / sinus surgeries?
TIVA, propofol and remi are associated with less bleeding, better visualization, less coughing on emergence, decreased PONV
Why is MR preferred for FESS
movement could cause neuro or opthalmic damage
Major complications associated with FESS
diplopia, CSF leak, CNS infection, stroke, carotid injury, death, orbital hematoma
Causes of major complications
perforation of roof of ethmoid sinus, injury to optic nerve or carotid artery during a sphnenoidecotmy
Minor complications associated with FESS
lip pain or numbness
use of N20 for ear surgeries
remember N20 is 34 x more soluble in blood than nitrogen
N20 will enter air cavities faster than nitrogen can leave
result is an increase in pressure
also risk of otitis, disarticulating of the stapes, impaired hearing
can also lead to PONV
how long should N20 be avoided for pts s/p reconstructive ear surgeries?
T or F, ear surgery alone is associated with increased PONV
T or F, PONV is not harmful to middle ear reconstruction?
F, it can undo it
facial nerve and otologic surgeries
up to 3% incidence of facial nerve paralysis
intra-op monitoring is usually performed so avoid MR
bridge connecting the L and R lobes of the thyroid gland
Thyroid gland innervation
Thyroidectomy anesthetic considerations
How can you tell if a pt is euthyroid
resting HR < 85
will decrease risk of thyroid storm by > 90%
Why are pts undergoing thyroidectomy at increased risk for airway issues?
potential for a large goiter, causing:
tracheal ring involvement
inflammation due to thyroiditis
medullary thyroid cancer is associated with MEN (multiple endocrine neoplasia)
this pt could have an diagnosed pheo
catecholamine release could mimic thyroid storm and vice versa
find out what the pre-op diagnosis is!!
What med is often used pre-op to render a pt euthyroid prior to thyroidectomy
Your pt shows up for a thyroidectomy and admits to not taking their lugol's solution for last week, what should you do?
Elective surgery should be cancelled
Pt position for thyroid surgery
Complications of thyroid surgery
recurrent or superior LN paralysis
-damage to RLN can lead to VC paralysis or airway obstruction
What actions are taken to prevent nerve damage during thyroidectomy?
Nerve monitoring with a NIM ETT
NDMR are avoided
What muscles are monitoring with EMG during thyroidectomy?
thyroarytenoid muscles (principle relaxers of the VC)
T or F, pts undergoing thyroidectomy are not at increased risk for eye injury
F, increased risk, possible exopthalmus
Why are hyperthyroid pts at increased risk for hepatic injury
accelerated biotransformation leading to increased metabolites
Use of NMB and thyroidectomy
Typically avoided due to use of nerve monitoring
If needed to use, use cautiously due to increased incidence of MG and myopathies in pts with thyrotoxicosis
T or F, hyperthyroidism itself increases the MAC and anesthetic requirements
T or F, a pt presenting with bleeding tonsils requiring re-operation does not require RSI
F, potentially swallowing blood and are thus considered full stomach
Anesthetic management for a bleeding tonsil
adequate venous access
adequate volume replacement (blood loss under estimated thus pt is more hypovolemic than thought)
no premedication as we want airway reflexes intact
Anesthesia risks associated with a peritonsillar abscess
GA can cause further obstruction, careful intubation to avoid disrupting the abscess
? awake intubation
? elective trach
difficult intubation as a result of trismus
supraglottic obstruction 2/2 infection
Diagnosis of epiglottitis
lateral neck x-ray may show characteristic thumb like epiglottic shadow
Why is trach set-up and ENT surgeon presence required for epiglottitis surgery?
Possibility of complete airway obstruction can occur at any time
Induction for epiglottitis
Careful inhalation induction
Avoid manipulation of the airway prior to induction
Pt breathing spontaneously but deep
sudden obstruction to breathing
Anesthesia management of FBO
don't turn partial obstruction into complete obstruction
must be ready to perform trach or cricothyroidectomy
gentle mask induction without PPV or cricoid pressure is preferred
Why is close observation required after removal of a FB?
Laryngeal and subglottic edema can occur up to 24 hours after FB is removed
Superior laryngeal nerve block
will anesthetize all laryngeal mucous membranes above the larynx?
use cautiously in full stomach pts as it may remove some protective reflexes
glossopharyngeal nerve block
innervates posterior tongue, oropharynx, tonsils, gag reflex
block can cause paralysis of the pharyngeal muscles
tongue relaxation will cause some airway obstruction
if both a superior laryngeal and glossopharyngeal nerve block are performed, which should be performed first to avoid airway obstruction?
perform SLN block first
is glossopharyngeal nerve block alone sufficient for awake intubation?
max dose cocaine for LA?
3 mg / kg
max dose lido for LA?
3.5 mg /kg?
max dose tetracaine for LA?
radical neck dissection
deep cervical lymph node and the tissues around them are removed as much as possible
major arteries, brachial plexus, 10th CN and phrenic nerve are preserved
Use of NDMR for neck dissection
contraindicated b/c surgeon needs to identify the nerves
Lefort osteotomy purpose
correct dental malocclusion
correct congential abn
correct maxillary deformities
lefort 1 fracture
simple horizontal fx of the lower maxilla just above the teeth and the palate
maxilla is separated from the palate
lefort 2 fracture
crosses the nasal bones on the ascending processes of the maxilla
crosses the medial and inferior orbital rims
separates maxilla from the face
lefort 3 fracture
high level transverse fx
crosses front of maxilla and the lacrimal bone and goes thru the orbits
Dural tears occur 25% of the time in Lefort __ and __ fxs
2 and 3
In what pts should nasal intubation be avoided?
Lefort 2 or 3 fx
nasal, orbital, or zygomatic fx
why is it especially important to give anti-emetics with a lefort osteotomy procedure?
jaw is wired shut at end
want to prevent PONV!
T or F, the eye can easily accommodate increases in volume?
F, pressure will increase with an increase in volume due to rigid wall
What factors can influence IOP
movement of aqueous humor
changes in blood volume
extraocular muscle tone
arterial BP and ventilation
T or F, succ increases IOP more than intubation
F, intubation increases IOP more than succ alone
what effect does an increase in the following have on IOP?
PaCO2 (hypovent)- incr
What effect do volatiles, N20, barbs, and benzos have on IOP?
What effect does succ have on IOP?
Increases IOP by 5-10 mmHg for 5-10 minutes after administration
What effect does diamox have on IOP?
Diamox is a carbonic anhydrase inhibitor
T or F, 2/3 of aqueous humor is an active secretory product of the carbonic anhydrase enzyme system?
Aqueous humor flow is r/t to what equation?
Respiratory _____, hy___thermia, and hypoxia will increase IOP.
Echothiapate is a _____ ____ and will ____ the effect of succ.
Most common pedi eye surgery in the US
Common SE of strabismus repair
oculocardiac reflex (bradycardia) and oculogastric reflex (vomiting)
Examples of open eye surgeries
corneal laceration repair
removal of FB
ruptured globe repair
secondary intraocular lens implantation
vitrectomy (ant and post)
wound leak repair
afferent fibers from cornea and conjunctiva to 1st branch of 5th CN= trigeminal nerve
Motor innervation of the extra-occular muscles
Motor fibers of the 3rd CN (oculomotor) to all eye muscles expect lateral rectus
Lateral rectus is innervated by the 6th CN (abducens)
What type of block is typically done for cataract surgery?
What does blockade of the facial nerve with 1% lido do?
Sensory anesthesia of the periorbital area and motor lid block
Why is hydraluronidase added to retro-bulbar injections?
enzyme that promotes the spread of anesthetic thru the muscle column
What are the 3 goals of the retrobulbar block?
abolishment of OCR
What's the difference btw retro and peri bulbar blocks?
retrobulbar block- needle enters intraorbital muscle cone (intraconal)
peribulbar block- needle does not enter infraorbital muscle cone (extraconal)
Most frequent complication of retrobulbar blocks
1% of cases
S/sx of hemorrhage from a retrobulbar block
immediate downward displacement of the eyeball
appearance of subconjunctival blood
serious complication that can interfere with retinal blood supply if excessive pressure develops
surgery is cancelled and drainage may be performed by the surgeon
SE of a retrobulbar block
LA spreads along optic nerve to central brainstem
pt becomes apneic
tx= ventilation and supportive tx until s/sx resolve
s/sx= SOB, dysphasia
SE of retrobulbar block
want to inject into cone, not directly into muscle
stop injecting if there is any rx!!
-what CN are involved
-which is afferent (sensory) and which is efferent
AKA five and dime reflex (CN 5 and 10)
afferent- CN 5 trigeminal
efferent- CN 10 vagal
Causes of OCR
pressure on eye
traction of extra ocular muscles
Most common surgery to see OCR
strabismus surgery in children
bradycardia, nodal rhythm, ectopy, asystole
d/c stimulus (surgeon usually)
T or F, the OCR will eventually fatigue itself with repeated traction on the extra ocular muscles
How does PaCO2 level affect incidence of bradycardia during strabismus surgery?
Hypoventilation and increased PaCO2 will increase the incidence of bradycardia
Disadvantage of peribulbar block over retrobulbar block
slower onset (placed further from optic and other nerves)
need for reinjection more often