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931: Advanced Principles of Anesthesia I > Anesthetic considerations for ophthalmic surgery > Flashcards

Anesthetic considerations for ophthalmic surgery Flashcards

1
Q

The leading cause of blindness in the world is

A

cataracts

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2
Q

_______ is the leading cause of new cases of blindness among adults aged 20-74 years

A

Diabetes

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3
Q

Other major causes of vision loss include

A

macular degeneration, glaucoma, and diabetic retinopathy

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4
Q

Types of eye surgery include

A

cataract, occuloplastics (ptosis repair), strabismus, cornea transplants or grafting, trabeculectomy, vitrectomy and retinal buckling, trauma- enucleation or orbital fracture repair, LASIX

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5
Q

_____ are two symmetrical bony enclosures in the front of the skull

A

orbits

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6
Q

Each orbit contains an

A

eyeball (globe) and its associated structures

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7
Q

The volume of each adult orbit is approximately

A

30 mL

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8
Q

The _______ (first branch of the internal carotid) passes into orbit through optic canal (lies inferolateral to optic nerve)

A

Ophthalmic artery

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9
Q

The visual axis (optic axis) is an

A

imaginary line from the midpoint of cornea to midpoint of retina or macula

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10
Q

The axial length is a measurement of the

A

visual axis

-measure preoperatively to determine appropriate intraocular lens

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11
Q

The normal axial length is

A

23 to 23.5 mm**
hyperopia (farsighted) globe is less than 22 mm long
myopia (nearsighted) has axial length >24 mm

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12
Q

A greater chance of puncturing the globe is possible with

A

myopia (nearsighted)

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13
Q

The globe is suspended in the

A

anterosuperior part of the orbit

-contained within three layers

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14
Q

The large posterior segment of the globe contains

A

vitreous humor, retina, macula, and root of optic nerve

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15
Q

The twelve cranial nerves are:

A
  1. olfactory
  2. optic
  3. oculomotor
  4. trochlear
  5. trigeminal
  6. abducens
  7. facial
  8. vestibulocochlear
  9. glossopharyngeal
  10. vagus
  11. accessory
  12. hypoglossal
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16
Q

The optic nerve is

A

not a true cranial nerve
-outgrowth of the brain**
-covered by meninges (pia, arachnoid, dura)
-anything injected into the nerve sheath can travel directly to the brain via CSF
Central retinal artery & vein surround the nerve

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17
Q

The oculomotor nerve is the primary

A

motor nerve to the extraocular muscles of the orbit (branches superiorly & inferiorly)

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18
Q

The oculomotor nerve sends parasympathetic fibers to

A

the ciliary ganglion

-causes constriction of the pupil

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19
Q

The oculomotor nerve sends sympathetic fibers to

A

control pupil dilation

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20
Q

The oculomotor nerve innervates the

A

superior rectus, inferior rectus, inferior oblique, medial rectus, & levator (upper eyelid)

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21
Q

The trochlear nerve provides

A

motor fibers to the superior oblique muscle

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22
Q

The trochlear nerve is the only orbital cranial

A

motor nerve that enters the orbit from outside the muscle cone

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23
Q

The trochlear nerve travels in a

A

medial direction to innervate the superior oblique muscle

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24
Q

The trigeminal nerve contains

A

sensory & motor components

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25
Q

The trigeminal nerve intracranial portion forms the

A

trigeminal ganglion

-three divisions: ophthalmic, maxillary, and mandibular

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26
Q

The ophthalmic branch of the trigeminal nerve provides sensation of

A

pain, touch and temperature to the cornea, ciliary body, iris, lacrimal gland, conjunctiva, nasal mucosa, eyelid, eyebrow, forehead, & nose

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27
Q

The maxillary branch of the trigeminal nerve provides for the sensation of

A

pain, touch, and temperature to the upper lip, nasal mucosa, and scalp muscles

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28
Q

The Ophthalmic nerve is a branch of

A

trigeminal nerve

forms three branches: lacrimal, frontal, nasociliary

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29
Q

The nasociliary nerve sends nerve fibers

A

medially and to the ciliary ganglion

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30
Q

The frontal branch is the

A

largest branch of ophthalmic nerve; further branches

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31
Q

The lacrimal nerve innervates

A

the lacrimal gland

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32
Q

The abducens nerve provides

A

motor function to the lateral rectus muscle

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33
Q

The facial nerve provides

A

motor function to the facial muscles
-upper and lower branches
upper branch innervates the orbicular muscle, superficial facial, and scalp muscles

34
Q

The vagus nerve provides

A

motor function to the intrinsic muscles in the larynx and heart
major parasympathetic visceral innervation
efferent pathway for the oculocardiac reflex

35
Q

Describe the six extraocular muscles of the eye.

A 
superior rectus
inferior rectus
medial rectus
lateral rectus
superior oblique
inferior oblique
36
Q

The superior rectus muscle

A

moves eye upward

12 o’clock

37
Q

The inferior rectus muscle moves

A

eye downward (6 o’clock)

38
Q

The medial rectus moves

A

eyeball nasally

39
Q

The lateral rectus moves

A

eyeball laterally

40
Q

The superior oblique rotates eyeball

A

on horizontal axis towards nose

41
Q

The inferior oblique rotates eyeball on

A

horizontal axis temporally

42
Q

The superior rectus muscle function & cranial nerve is

A

supraduction & CN III***

43
Q

The inferior rectus muscle function & cranial nerve is

A

infraduction & CN III****

44
Q

The medial rectus muscle function & cranial nerve is

A

adduction & CNIII*******

45
Q

The lateral rectus muscle function & cranial nerve is

A

abduction & CN VI*******

46
Q

The superior oblique muscle function & cranial nerve is

A

intorsion, depression & CN IV****

47
Q

The inferior oblique muscle function & cranial nerve is

A

extorsion, elevation & CN III

48
Q

The ____ muscle is used for raising upper eyelids

A

levator

49
Q

The _____ muscle contracts the eyelid

A

orbicular

  • three divisions of muscles arranged around the eyeball: orbital, palpebral, tarsal
  • akinesia of these muscles is generally desired for ocular procedures
50
Q

Contraction of the eyelid muscles can

A

increase ICP

51
Q

General anesthesia considerations for eye surgeries include

A 
changes in intraocular pressure
CV response to traction on extraocular muscles
absorption of topically administered drugs
open eye injury (GA vs local)
succinylcholine increases IOP
Echothiopate drops (systemic effects)
complication of expansion of gas bubble
post retrobulbar apnea syndrome
laser surgery
52
Q

Intraocular pressure maintains the

A

normal shape & optical properties of the eye

53
Q

Normal IOP is

A

12-20 mmHg***

54
Q

Determinants of IOP include:

A

aqueous humor dynamics- balance between production & elimination of aqueous humor
changes in choroidal blood volume- vascular meshwork in the posterior chamber
rise in venous blood pressure
extraocular muscle tone

55
Q

The aqueous is a thin, watery fluid that

A

fills the space in the anterior chamber between the cornea & the iris

  • nourishes the cornea & lens
  • gives the front of the eye its form & shape
56
Q

Aqueous fluid is continually produced by

A

ciliary body just behind the iris

- drains out of the eye via the trabecular meshwork into the aqueous veins and eventually into the veins of the orbit

57
Q

The following increases IOP:

A 
blinking (5 mmHg)
squinting (26 mmHg)
CV/respiratory variables (CVP, ABP, PaCO2)
laryngoscopy & intubation
external pressure/positioning 
succinylcholine
topical anticholinergics
58
Q

The following decrease IOP:

A 
volatile anesthetics
intravenous anesthetics (except for ketamine)
non-depolarizing muscle relaxants
benzodiazepines
narcotics
59
Q

Succinylcholine increases IOP by

A

5-10 mmHg for 5-10 minutes
mechanism is unclear
may be a result of prolonged contraction of extraocular muscles

60
Q

Describe the oculocardiac reflex.

A

afferent transmission via trigeminal nerve**
efferent transmission via vagus nerve***
known as the “five & dime reflex”

61
Q

The oculocardiac reflex can occur with

A

pain, pressure or manipulation of the eyeball

traction on medial rectus muscle is common

62
Q

Symptoms of the oculocardiac reflex include

A

cardiac dysrhythmias (bradycardia, sinus arrest, vfib, AV block, ventricular ectopy) and negative inotropy

63
Q

The oculocardiac reflex is most commonly seen in

A

pediatric strabismus surgery*****
transient cardiac arrest occurs in 1:2200 strabismus surgeries
may be attenuated by pretreatment with anticholinergics

64
Q

Treatment of oculocardiac reflex includes

A

stop stimulus
administer atropine/glycopyrrolate
infiltration of local anesthetic to the medial rectus muscle**

65
Q

Surgery for detached retina includes

A

a small gas bubble injected into posterior chamber to hold retina in place

66
Q

The gas bubble most commonly used for retina surgery is

A

Sulfur hexafluoride*****

  • inert, poorly diffusible gas
  • much less soluble in blood than nitrogen & N2O
  • DOA is 10 days*****
  • Nitrogen from inhaled enters the bubble faster than SH allowing the bubble to expand (doubles in 24 hours)**
67
Q

Inhaled 70% N2O can _____ the size of the bubble and quickly increase IOP in detached retina surgeries

A

triple**

-can be reversed if N2O discontinued (within 18 minutes), the pressure changes can lead to negative outcomes

68
Q

With detached retina surgeries:

A

DISCONTINUE N2O 20 minutes prior to injection to allow for washout
AVOID N2O for 10 days after SH (5 days if injected air)

69
Q

Describe considerations with atropine/scopolamine with eye surgery

A

anticholinergic

  • central cholinergic syndrome
  • scopolamine can cause disorientation in some patients
70
Q

Describe considerations with epinephrine with eye surgery.

A

sympathetic agonist

tachycardia, arrhythmias, HTN, & headache

71
Q

Describe considerations with phenylephrine with eye surgery.

A

alpha agonist

HTN, arrhythmias, headache, reflex bradycardia

72
Q

Describe considerations with cyclopentolate with eye surgery

A

synthetic anticholinergic

disorientation, psychosis, & seizures

73
Q

Describe considerations with pilocarpine with eye surgery.

A

muscarinic alkaloid

miosis, redness, irritation

74
Q

Describe considerations with carbachol with eye surgery.

A

synthetic carbamyl ester of choline

used if not responsive to pilocarpine

75
Q

Describe considerations with physostigmine with eye surgery.

A

indirect-acting anticholinesterase

miosis

76
Q

Describe considerations with echothipate with eye surgery

A

indirect-acting organophosphorous cholinesterase inhibitor

miosis

77
Q

Echothiophate is used for treatment of

A

glaucoma
IRREVERSIBLE**** cholinesterase inhibitor
lasts 3-6 weeks after discontinuation

78
Q

Systemic absorption of echothiophate leads to

A

decreased plasma cholinesterase activity
succinylcholine will be PROLONGED** 20-30 minutes - use with caution
may prolong mivacurium and ester-linked local anesthetics

79
Q

Describe considerations with timolol with eye surgeries.

A

potent non-selective beta-blocker

-bradycardia, asthma, CHF

80
Q

Describe considerations with acetylcholine with eye surgeries.

A

Cholinergic agonist

miosis, bradycardia, bronchospasm, hypotension

81
Q

Describe considerations with acetazolamide with eye surgeries.

A

Carbonic anhydrase inhibitor
-reduces secretion of aqueous from ciliary body, mild diuretic, hypokalemia, acidosis, hematuria, paresthesia, gastric distress, flaccid paralysis, seizures
avoid with renal/hepatic disease****

931: Advanced Principles of Anesthesia I (22 decks)

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