ENT Anesthesia

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ENT Anesthesia
2014-04-12 10:52:00
BC Nurse Anesthesia

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  1. Level of the larynx in the adult?
    • Adult= C4-6
    • Pedi= C3-5
  2. How many cartilages form the larynx?
  3. Larynx arterial blood supply
    subclavian artery to inferior thyroid artery to inferior laryngeal artery
  4. Larynx venous blood drainage
    inferior laryngeal vein to brachiocephalic vein to SVC
  5. 3 single cartilages of the larynx
    epiglottic, thyroid, cricoid
  6. 3 paired cartilages of the larynx
    arytenoids, corniculate, cuneiform
  7. What forms the Adam's apple?
    • thyroid cartilage
    • largest of the laryngeal cartilages
  8. Thyrohyoid membrane
    Attaches thyroid cartilage to the hyoid bone
  9. Narrowest part of the pedi airway
    cricoid cartilage
  10. cricothyroid ligament
    Attaches cricoid cartilage to the thyroid ligament
  11. First cartilage seen on DL
  12. List the following structures from cephalad to caudad: cricotracheal ligament, thyroid cartilage, 1st tracheal ring, thyrohyoid membrane, cricoid cartilage, cricothyroid membrane, hyoid bone
    • hyoid bone
    • thyrohyoid membrane
    • thyroid cartilage
    • cricothyroid membrane
    • cricoid cartilage
    • cricotracheal ligament
    • 1st tracheal ring
  13. 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
  14. Narrowest part of adult airway
  15. Position of the rims glottidis
    -forced respiration
    • resting= narrow and wedge shaped
    • forced respiration= wide and kite shaped
    • phonation= slit like as VC are closely approximated
  16. rima glottidis
    opening btw the VC
  17. What are the 3 functions of the larynx?
    • protect airway
    • respiration
    • vocalization
  18. 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
  19. Function of the extrinsic laryngeal muscles
    move the larynx as a whole
  20. extrinsic laryngeal muscles
    how many?
    2 main groups?
    • 8
    • infrahyoid and suprahyoid
  21. function of the infra hyoid laryngeal muscles
    depress hyoid and larynx
  22. function of the supra hyoid laryngeal muscles
    elevate hyoid and larynx
  23. 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
  24. VC should be ____ during swallowing and ____ during inspiration
    • closed
    • open
  25. 4 classifications of intrinsic laryngeal muscles
    • adductors and abductors
    • sphincters
    • tensors
    • relaxers
  26. All but one of the _____ laryngeal muscles are supplied by the _____.
    • intrinsic
    • RLN
  27. Only the ______ is innervated by the external laryngeal nerve.  All the other intrinsic muscles are supplied by the ____.
    • cricothyroid
    • RLN
  28. The RLN is a branch of what CN?
    10th CN, vagus
  29. Major tensor intrinsic laryngeal muscles
    • cricothyroid muscles
    • tense and elongate the VC, this causes voice pitch to rise
  30. Abductor intrinsic laryngeal muscle
    • posterior cricoarytenoid
    • open VC by widening the rims rims
  31. Major adductor intrinsic laryngeal muscle
    • lateral cricoarytenoid
    • close VC
    • work with transverse arytenoid muscles
    • air gets pushed thru rims glottides to cause vibration of vocal ligaments and to cause phonation
  32. The transverse arytenoid muscles cause
    adduction, work with the lateral cricoarytenoid muscles
  33. Thyroarytenoid muscle function
    • relaxer
    • relax VC and lower the voice
  34. intrinsic muscles that fall into the category of sphincters
    • lateral cricoarytenoid
    • oblique arytenoids
    • transverse arytenoids
    • aryepiglottic muscles
  35. What nerves supply the larynx?
    Vagus, RNL, and superior LN
  36. What is the only intrinsic laryngeal muscle NOT innervated by the RNL?
    the cricothyroid muscle
  37. What supplies sensory innervation of larynx down to the VC?
    Internal branch of the superior LN
  38. Function of the external branch of the superior laryngeal nerve
    • motor
    • innervates cricothyroid muscle and inferior pharyngeal muscle
  39. What nerve provides sensory innervation of the larynx below the VC?
  40. Thyroid or parathyroid surgery has the potential to cause damage to what nerve?
  41. Unilateral RLN injury
    • cord on the injured side will assume a paramedian position
    • hoarse and weak voice
    • increased risk of aspiration
  42. What occurs with bilateral ischemia of the RLN?
    Laryngospasm causing complete airway obstruction
  43. What causes laryngospasm?
    What nerve is involved
    • Spasm of glottic muscles
    • superior LN
  44. The VC are at the level of the?
    laryngeal prominence
  45. cricoid cartilage is at the level of the ___ vertebra
  46. 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
  47. 3 parts of the pharynx
    • nasopharynx- posterior to nose and superior to soft palate
    • oropharynx- posterior to mouth
    • laryngopharynx- posterior to larynx
  48. 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
  49. 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
  50. T or F, MR is typically NOT required for microlaryngoscopy
  51. Why is microlaryngoscopy associated with 1.5-4% incidence of Mi or ischemia?
    • suspended laryngoscope is stimulating
    • can cause HTN, tachycardia, arrythmias
  52. Possible techniques used to perform microlaryngoscopy
    • apneic- alternate mask ventilation with surgical incision, use TIVA
    • spontaneous breathing with deep anesthesia (tricky)
    • jet ventilation
  53. 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%
  54. Contraindications / risks of jet ventilation
    • pedi, obesity, emphysematous bullae
    • risk= barotrauma
  55. Laser
    light amplification by simulated emission of radiation
  56. CO2 laser
    • most commonly used laser
    • suitable for removing lesions on VC and larynx
    • produces radiation with a wavelength of 0.01 mm
  57. YAG and ARGON laser
    • deep and penetrating effects
    • suitable for detached retinas
    • shorter wl than CO2 laser
  58. Major anesthesia considerations r/t laser use
    airway fire and eye protection (for all in room!!)
  59. Strategies to avoid an airway fire
    • fill cuff with NS or methylene blue
    • avoid N20 (combustable)
    • FiO2 <= 30%
  60. Steps to take if an airway fire does occur
    • First step = D/C O2
    • Remove ETT
    • re-intubate trachea
    • flush pharynx with cold NS
    • rigid broch to check for damage and presence of foreign bodies 
    • possibly steroids, humidified gas, abx
  61. T or F, the nasal mucosa has minimal blood supply
    F, rich blood supply
  62. considerations r/t pts undergoing nasal or sinus surgeries
    • pre-op nasal obstruction
    • nasal polyps are associated with asthma and CF
  63. max dose of cocaine
    3 mg / kg
  64. SE of cocaine
    • HTN and ectopic ventricular activity
    • cocaine inhibits reuptake of NE
  65. 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
  66. 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
  67. Why is MR preferred for FESS
    movement could cause neuro or opthalmic damage
  68. Major complications associated with FESS
    • diplopia, CSF leak, CNS infection, stroke, carotid injury, death, orbital hematoma
    • 1%
  69. Causes of major complications
    perforation of roof of ethmoid sinus, injury to optic nerve or carotid artery during a sphnenoidecotmy
  70. Minor complications associated with FESS 
    • peri-orbital emphysema
    • ecchymosis
    • lip pain or numbness
    • bronchospasm
    • epistaxsis
    • 5%
  71. use of N20 for ear surgeries
    • not recommended
    • 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 
  72. how long should N20 be avoided for pts s/p reconstructive ear surgeries?
    6 weeks
  73. T or F, ear surgery alone is associated with increased PONV
  74. T or F, PONV is not harmful to middle ear reconstruction?
    F, it can undo it
  75. facial nerve and otologic surgeries
    • up to 3% incidence of facial nerve paralysis
    • intra-op monitoring is usually performed so avoid MR
  76. thyroid isthmus
    bridge connecting the L and R lobes of the thyroid gland
  77. Thyroid gland innervation
  78. Thyroidectomy anesthetic considerations
    • euthryoid status
    • airway!!
  79. How can you tell if a pt is euthyroid
    • TFT
    • resting HR < 85
    • will decrease risk of thyroid storm by > 90%
  80. Why are pts undergoing thyroidectomy at increased risk for airway issues?
    • potential for a large goiter, causing:
    • tracheal deviation
    • tracheal ring involvement
    • inflammation due to thyroiditis
  81. MEN 
    • 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!!
  82. What med is often used pre-op to render a pt euthyroid prior to thyroidectomy
    lugol's solution
  83. 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
  84. Pt position for thyroid surgery
    beach chair
  85. Complications of thyroid surgery
    • recurrent or superior LN paralysis
    • -damage to RLN can lead to VC paralysis or airway obstruction
  86. What actions are taken to prevent nerve damage during thyroidectomy?
    • Nerve monitoring with a NIM ETT
    • NDMR are avoided
  87. What muscles are monitoring with EMG during thyroidectomy?
    thyroarytenoid muscles (principle relaxers of the VC)
  88. T or F, pts undergoing thyroidectomy are not at increased risk for eye injury
    F, increased risk, possible exopthalmus
  89. Why are hyperthyroid pts at increased risk for hepatic injury
    accelerated biotransformation leading to increased metabolites
  90. 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 
  91. T or F, hyperthyroidism itself increases the MAC and anesthetic requirements
  92. 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
  93. Anesthetic management for a bleeding tonsil
    • T+C
    • 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
  94. Anesthesia risks associated with a peritonsillar abscess
    • resp obstruction
    • GA can cause further obstruction, careful intubation to avoid disrupting the abscess
    • ? awake intubation
    • ? elective trach
    • difficult intubation as a result of trismus
    • distorted anatomy
  95. Epiglottitis
    supraglottic obstruction 2/2 infection
  96. Epiglottitis s/sx
    • sore throat
    • dysphagia
    • muffled voice
    • resp distress
  97. Diagnosis of epiglottitis
    • DL
    • lateral neck x-ray may show characteristic thumb like epiglottic shadow
  98. Why is trach set-up and ENT surgeon presence required for epiglottitis surgery?
    Possibility of complete airway obstruction can occur at any time
  99. Induction for epiglottitis
    • Careful inhalation induction
    • Avoid manipulation of the airway prior to induction
    • Pt breathing spontaneously but deep 
  100. S/sx FBO
    • sudden obstruction to breathing
    • croupy cough
    • wheezing
    • hoarseness
  101. 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
  102. Why is close observation required after removal of a FB?
    Laryngeal and subglottic edema can occur up to 24 hours after FB is removed
  103. 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
  104. glossopharyngeal nerve block
    • 9th CN
    • innervates posterior tongue, oropharynx, tonsils, gag reflex
    • block can cause paralysis of the pharyngeal muscles
    • tongue relaxation will cause some airway obstruction
  105. if both a superior laryngeal and glossopharyngeal nerve block are performed, which should be performed first to avoid airway obstruction?
    perform SLN block first
  106. is glossopharyngeal nerve block alone sufficient for awake intubation?
  107. max dose cocaine for LA?
    3 mg / kg
  108. max dose lido for LA?
    3.5 mg /kg?
  109. max dose tetracaine for LA?
  110. 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
  111. Use of NDMR for neck dissection
    contraindicated b/c surgeon needs to identify the nerves
  112. Lefort osteotomy purpose
    • correct dental malocclusion
    • correct congential abn
    • correct maxillary deformities
  113. lefort 1 fracture
    • simple horizontal fx of the lower maxilla just above the teeth and the palate
    • maxilla is separated from the palate
  114. 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
  115. lefort 3 fracture
    • high level transverse fx
    • crosses front of maxilla and the lacrimal bone and goes thru the orbits
  116. Dural tears occur 25% of the time in Lefort __ and __ fxs
    2 and 3
  117. In what pts should nasal intubation be avoided?
    • Lefort 2 or 3 fx
    • nasal, orbital, or zygomatic fx
  118. why is it especially important to give anti-emetics with a lefort osteotomy procedure?
    • jaw is wired shut at end
    • want to prevent PONV!
  119. T or F, the eye can easily accommodate increases in volume?
    F, pressure will increase with an increase in volume due to rigid wall
  120. Normal IOP
    12-20 mmHg
  121. What factors can influence IOP
    • movement of aqueous humor
    • changes in blood volume
    • CVP
    • extraocular muscle tone
    • arterial BP and ventilation
  122. T or F, succ increases IOP more than intubation
    F, intubation increases IOP more than succ alone
  123. what effect does an increase in the following have on IOP?
    • CVP- incr
    • ABP- incr
    • PaCO2 (hypovent)- incr
    • hypoxia- incr
  124. What effect do volatiles, N20, barbs, and benzos have on IOP?
    Increased IOP
  125. What effect does succ have on IOP?
    Increases IOP by 5-10 mmHg for 5-10 minutes after administration
  126. What effect does diamox have on IOP?
    • Diamox is a carbonic anhydrase inhibitor
    • decreases IOP
  127. T or F, 2/3 of aqueous humor is an active secretory product of the carbonic anhydrase enzyme system?
  128. Aqueous humor flow is r/t to what equation?
    Poiseuille's Law
  129. Respiratory _____, hy___thermia, and hypoxia will increase IOP.
    • acidosisi
    • hypoxia
    • hyperthermia
  130. Echothiapate is a _____ ____ and will ____ the effect of succ.
    • cholinesterase inhibitor
    • prolong
  131. Most common pedi eye surgery in the US
    strabismus repair
  132. Common SE of strabismus repair
    oculocardiac reflex (bradycardia) and oculogastric reflex (vomiting)
  133. Examples of open eye surgeries
    • Cataract extraction
    • corneal laceration repair
    • corneal transplant
    • removal of FB
    • ruptured globe repair
    • secondary intraocular lens implantation
    • vitrectomy (ant and post)
    • wound leak repair
    • peripheral iridectomy
  134. Eye sensation
    afferent fibers from cornea and conjunctiva to 1st branch of 5th CN= trigeminal nerve
  135. 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)
  136. What type of block is typically done for cataract surgery?
    Peribulbar block
  137. What does blockade of the facial nerve with 1% lido do?
    Sensory anesthesia of the periorbital area and motor lid block
  138. Why is hydraluronidase added to retro-bulbar injections?
    enzyme that promotes the spread of anesthetic thru the muscle column
  139. What are the 3 goals of the retrobulbar block?
    • anesthesia 
    • akinesia 
    • abolishment of OCR
  140. 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)
  141. Most frequent complication of retrobulbar blocks
    • hemorrhage
    • 1% of cases
  142. 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
  143. Brainstem anesthesia
    • 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
  144. IM injection
    • SE of retrobulbar block
    • want to inject into cone, not directly into muscle
    • stop injecting if there is any rx!!
  145. Oculocardiac reflex
    -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
  146. Causes of OCR
    • pressure on eye
    • traction of extra ocular muscles
    • orbital hematoma
    • ocular trauma
    • eye pain
  147. Most common surgery to see OCR
    strabismus surgery in children
  148. S/sx OCR
    • bradycardia, nodal rhythm, ectopy, asystole
    • somnulence
    • nausea
  149. OCR treatment
    • d/c stimulus (surgeon usually)
    • give anti-muscarinic
  150. T or F, the OCR will eventually fatigue itself with repeated traction on the extra ocular muscles
  151. How does PaCO2 level affect incidence of bradycardia during strabismus surgery?
    • Hypoventilation and increased PaCO2 will increase the incidence of bradycardia
    • maintain normocarbia
  152. Disadvantage of peribulbar block over retrobulbar block
    • slower onset (placed further from optic and other nerves)
    • need for reinjection more often