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

Anesthetic considerations for ophthalmic surgery Flashcards

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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
The trigeminal nerve intracranial portion forms the
trigeminal ganglion | -three divisions: ophthalmic, maxillary, and mandibular
26
The ophthalmic branch of the trigeminal nerve provides sensation of
pain, touch and temperature to the cornea, ciliary body, iris, lacrimal gland, conjunctiva, nasal mucosa, eyelid, eyebrow, forehead, & nose
27
The maxillary branch of the trigeminal nerve provides for the sensation of
pain, touch, and temperature to the upper lip, nasal mucosa, and scalp muscles
28
The Ophthalmic nerve is a branch of
trigeminal nerve | forms three branches: lacrimal, frontal, nasociliary
29
The nasociliary nerve sends nerve fibers
medially and to the ciliary ganglion
30
The frontal branch is the
largest branch of ophthalmic nerve; further branches
31
The lacrimal nerve innervates
the lacrimal gland
32
The abducens nerve provides
motor function to the lateral rectus muscle
33
The facial nerve provides
motor function to the facial muscles -upper and lower branches upper branch innervates the orbicular muscle, superficial facial, and scalp muscles
34
The vagus nerve provides
motor function to the intrinsic muscles in the larynx and heart major parasympathetic visceral innervation efferent pathway for the oculocardiac reflex
35
Describe the six extraocular muscles of the eye.
``` superior rectus inferior rectus medial rectus lateral rectus superior oblique inferior oblique ```
36
The superior rectus muscle
moves eye upward | 12 o'clock
37
The inferior rectus muscle moves
eye downward (6 o'clock)
38
The medial rectus moves
eyeball nasally
39
The lateral rectus moves
eyeball laterally
40
The superior oblique rotates eyeball
on horizontal axis towards nose
41
The inferior oblique rotates eyeball on
horizontal axis temporally
42
The superior rectus muscle function & cranial nerve is
supraduction & CN III*******
43
The inferior rectus muscle function & cranial nerve is
infraduction & CN III******
44
The medial rectus muscle function & cranial nerve is
adduction & CNIII*********
45
The lateral rectus muscle function & cranial nerve is
abduction & CN VI*********
46
The superior oblique muscle function & cranial nerve is
intorsion, depression & CN IV******
47
The inferior oblique muscle function & cranial nerve is
extorsion, elevation & CN III
48
The ____ muscle is used for raising upper eyelids
levator
49
The _____ muscle contracts the eyelid
orbicular - three divisions of muscles arranged around the eyeball: orbital, palpebral, tarsal - akinesia of these muscles is generally desired for ocular procedures
50
Contraction of the eyelid muscles can
increase ICP
51
General anesthesia considerations for eye surgeries include
``` 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
Intraocular pressure maintains the
normal shape & optical properties of the eye
53
Normal IOP is
12-20 mmHg*******
54
Determinants of IOP include:
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
The aqueous is a thin, watery fluid that
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
Aqueous fluid is continually produced by
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
The following increases IOP:
``` blinking (5 mmHg) squinting (26 mmHg) CV/respiratory variables (CVP, ABP, PaCO2) laryngoscopy & intubation external pressure/positioning succinylcholine topical anticholinergics ```
58
The following decrease IOP:
``` volatile anesthetics intravenous anesthetics (except for ketamine) non-depolarizing muscle relaxants benzodiazepines narcotics ```
59
Succinylcholine increases IOP by
5-10 mmHg for 5-10 minutes mechanism is unclear may be a result of prolonged contraction of extraocular muscles
60
Describe the oculocardiac reflex.
afferent transmission via trigeminal nerve**** efferent transmission via vagus nerve***** known as the "five & dime reflex"
61
The oculocardiac reflex can occur with
pain, pressure or manipulation of the eyeball | traction on medial rectus muscle is common
62
Symptoms of the oculocardiac reflex include
cardiac dysrhythmias (bradycardia, sinus arrest, vfib, AV block, ventricular ectopy) and negative inotropy
63
The oculocardiac reflex is most commonly seen in
pediatric strabismus surgery***** transient cardiac arrest occurs in 1:2200 strabismus surgeries may be attenuated by pretreatment with anticholinergics
64
Treatment of oculocardiac reflex includes
stop stimulus administer atropine/glycopyrrolate infiltration of local anesthetic to the medial rectus muscle****
65
Surgery for detached retina includes
a small gas bubble injected into posterior chamber to hold retina in place
66
The gas bubble most commonly used for retina surgery is
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
Inhaled 70% N2O can _____ the size of the bubble and quickly increase IOP in detached retina surgeries
triple**** | -can be reversed if N2O discontinued (within 18 minutes), the pressure changes can lead to negative outcomes
68
With detached retina surgeries:
DISCONTINUE N2O 20 minutes prior to injection to allow for washout AVOID N2O for 10 days after SH (5 days if injected air)
69
Describe considerations with atropine/scopolamine with eye surgery
anticholinergic - central cholinergic syndrome - scopolamine can cause disorientation in some patients
70
Describe considerations with epinephrine with eye surgery.
sympathetic agonist | tachycardia, arrhythmias, HTN, & headache
71
Describe considerations with phenylephrine with eye surgery.
alpha agonist | HTN, arrhythmias, headache, reflex bradycardia
72
Describe considerations with cyclopentolate with eye surgery
synthetic anticholinergic | disorientation, psychosis, & seizures
73
Describe considerations with pilocarpine with eye surgery.
muscarinic alkaloid | miosis, redness, irritation
74
Describe considerations with carbachol with eye surgery.
synthetic carbamyl ester of choline | used if not responsive to pilocarpine
75
Describe considerations with physostigmine with eye surgery.
indirect-acting anticholinesterase | miosis
76
Describe considerations with echothipate with eye surgery
indirect-acting organophosphorous cholinesterase inhibitor | miosis
77
Echothiophate is used for treatment of
glaucoma IRREVERSIBLE****** cholinesterase inhibitor lasts 3-6 weeks after discontinuation
78
Systemic absorption of echothiophate leads to
decreased plasma cholinesterase activity succinylcholine will be PROLONGED**** 20-30 minutes - use with caution may prolong mivacurium and ester-linked local anesthetics
79
Describe considerations with timolol with eye surgeries.
potent non-selective beta-blocker | -bradycardia, asthma, CHF
80
Describe considerations with acetylcholine with eye surgeries.
Cholinergic agonist | miosis, bradycardia, bronchospasm, hypotension
81
Describe considerations with acetazolamide with eye surgeries.
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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