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NA 1 > Eye Anesthesia - Exam 5 > Flashcards

Eye Anesthesia - Exam 5 Flashcards

1
Q

What are the requirements of Ophthalmic surgery?

A

Safety

Akinesia

Analgesia

Minimal Bleeding

Avoidance or obtundation of oculaocardic reflex

Control of intraocular pressure

Awareness of drug interactions

Smooth emergence

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2
Q

3 layers of the wall of the globe

A
  1. sclera = outermost layer
  2. uveal tract = middle layer
  3. retina = inner layer
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3
Q

Characteristics of the sclera

A

-tough, fibrous
-the white part
-continuous with cornea anteriorly

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4
Q

The place where the cornea and sclera meet is called

A

limbus

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5
Q

____% of focus power cones from curvature of cornea

A

60%

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6
Q

Uveal tract: 3 structures

A
  1. choroid
  2. iris
  3. ciliary body
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7
Q

What is the main blood supply to the eye? What does it divide into?

A

Ophthalmic artery

Central retinal artery

Posterior ciliary artery

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8
Q

How are ocular surgeries classified and why is this important?

A

Extraocular or intraocular.

Anesthetic considerations are different for each category

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9
Q

What is the choroid

A

large layer of blood vessels located posteriorly

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10
Q

The _____ is the pigmented portion of the eye that controls light entry with muscle fibers that change size of pupil

A

iris

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11
Q

SNS stimulation causes pupillary ______
PNS stimulation causes pupillary ______

A

dilation
constriction (meiosis)

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12
Q

What do ciliary bodies do

A

produce aqueous humor

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13
Q

What is uveitis

A

Inflammation of the uveal tract (iris, ciliary body, choroid)

ending in itis - inflammation

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14
Q

What is the retina

A

highly specialized nerve tissue that is consistent with optic nerve

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15
Q

T/F the retina gets oxygen and nourishment from its dense capillary network

A

FALSE

choroid plexus supplies blood, no capillaries in retina

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16
Q

Why is retinal detachment bad

A

it detaches from choroid plexus (which supplies all its blood) so it becomes ischemic and is a major cause of vision loss

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17
Q

T/F the pars plana is a safe entrance site for vitrectomy procedures

A

TRUE

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18
Q

Center of the eye is filled with ______

A

vitreous fluid

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19
Q

What is the function of the superior and inferior ophthalmic veins?

A

Transport venous blood to the cavernous sinus

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20
Q

What is the equation for intraocular perfusion pressure?

A

MAP - IOP

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21
Q

Normal range for IOP

A

10-21.7mmHg

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22
Q

Because the globe is relatively noncompliant, what factors determine IOP?

A

Choroidal blood volume, aqueous fluid volume, and extraocular muscle tone

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23
Q

What is the aqueous humor and why is it important to ocular surgery?

A

A clear watery fluid that fills the space between the cornea and the lens.

The formation and drainage of the aqueous humor influence IOP.

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24
Q

Where is the aqueous humor produce and where is it reabsorbed?

A

Produced by the ciliary process in the posterior chamber

Reabsorbed by the canal of Schlemm in the anterior chamber

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25
Q

Cause of retinal detachment

A

traction of the vitreous on the retina

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26
Q

Layers of the eyelid

A

skin, muscle, tarsal plate of cartilage, conjunctiva

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27
Q

Lacrimal gland sits where

A

superior temporal orbit

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28
Q

CN that move the eye

A

3,4,6
oculomotor, trochlear, abducens

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29
Q

Local anesthetic block of the ciliary ganglion produces a ________ pupil

A

fixed and mid-dilated

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30
Q

What occurs when the oculocardiac reflex (trigeminovagal reflex) is triggered?

A

traction on extraocular muscles or pressure on globe causes bradycardia, AV block, ventricular ectopy, or asystole

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31
Q

T/F oculocardiac reflex is fairly common

A

TRUE

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32
Q

T/F the oculocardiac reflex fatigues with repeated stimulation

A

TRUE

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33
Q

oculocardiac reflex seen most often with traction on which muscle, which population, and which surgery

A

medial rectus (extraocular muscle)
children
strabismus surgery (medial rectus muscle)

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34
Q

Afferent vs efferent branch of oculocardiac reflex

A

afferent = orbital contents -> ciliary ganglion -> ophthalmic division (V1) of trigeminal n
efferent = vagus nerve to heart

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35
Q

T/F retrobulbar block is effective at preventing oculocardiac reflex

A

FALSE

not always.

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35
Q

Stimuli for oculocardiac reflex

A

-traction to extra ocular muscles (medius rectus)
-strabismus surgery (children)
-pressure on globe or conjunctiva
-ocular manipulation or pain
-ocular injection (blocks)

-retrobulbar block
-manipulation after orbital enucleation
-ocular trauma

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36
Q

First step if pt experiences oculocardiac reflex

A

tell surgeon to stop manipulation

then make sure they are deep enough, give atropine

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37
Q

Dose of atropine for oculocardiac reflex

A

0.02mg/kg increments

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38
Q

If atropine and deepening sedation don’t work, what can we ask surgeon to do during oculocardiac reflex

A

infiltrate medius rectus muscle with some local anesthetic

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39
Q

Things that will exacerbate oculocardiac reflex

A

hypoxia, hypercapnia, acidosis, inadequate depth of anesthesia

*key concept/testable

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40
Q

What are the 2 factors that regulate* IOP?

A
  1. volume of aqueous humor
  2. volume of blood in choroid plexus
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41
Q

3 Main factors that influence IOP

A

External pressure on the eye

Scleral rigidity

Changes in intraocular contents that are semisolid (lens, vitreous, or intraocular tumor) or fluid (blood and aqueous humor)

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42
Q

Major control of intraocular tension is exerted by

A

the fluid content (aqueous humor)

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43
Q

T/F increases in choroidal blood volume cause slow increases in IOP

A

FALSE

very quick increase in IOP

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44
Q

What increases IOP?

A

Hypercarbia

hypoxemia

increased CVP

increased MAP

Laryngoscopy/intubation

Straining/coughing

Succinylcholine

N2O (if SF bubble in place)

Trandelenburg position

Prone

External compression by facemask

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45
Q

What decreases IOP?

A

Hypocarbia

decreased cvp

decreased MAP

volatile anesthetics

N2O

Nondepolarizing NMB

Propofol

Opioids

Benzos

Hypothermia

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46
Q

True or false: Anticholinergics do not increase IOP

A

True

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47
Q

True or false LMA placement/removal has significant effect on IOP

A

False, minimal

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48
Q

Ketamine should be avoided in eye surgery, but not because of IOP effects. Why is it contraindicated?

A

It causes rotary nystagmus and blepharospasm

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49
Q

What can cause dysrhythmias during eye surgery?

A

-traction on extraocular muscles
-pressure on globe
-ocular manipulation
-ocular pain

=bradycardia, AV blk, vent ectopy, asystole

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50
Q

What is A?

A

vitreous body

-fills globe centrally with vitreous humor

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51
Q

What is B?

A

Lens

-REFRACTS rays of light passing thru cornea and pupil to FOCUS image onto retina

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52
Q

What is C?

A

Cornea

-highly vascular and transparent, PERMITS light passing

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53
Q

What is D?

A

**Pupil

-part of the iris, CONTROLS AMOUNT of light entering eye

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54
Q

What is E?

A

**Iris

-colored part containing dilator and sphincter muscle fibers controlling CENTRAL APERTURE

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55
Q

What is F?

A

Sclera

-fibrous, white OUTER LAYER, protective and MAINTAINS EYE SHAPE

this is tricky with the retina being so close, be careful

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56
Q

What is G?

A

Optic n

-SENDS electrical signals to brain to make images

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57
Q

What is H?

A

Retina

-posterior aspect of eye, CONVERTS light into electrical signals

this is tricky with the sclera being so close, be careful

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58
Q

Volume of each orbit:

A

~30mL

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59
Q

Average globe diameter:

A

23.5mm ~1in

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60
Q

Which bones are part of the orbit?

A

-frontal
-zygomatic
-greater wing of sphenoid
-maxilla
-palatine
-lacrimal
-ethmoid

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61
Q

What transmits the optic nerve and ophthalmic artery? What about everything else?

A

optic foramen

superior orbital fissure

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62
Q

3 layers of eye:

A

Sclera
Uveal Tract (contains Iris, Ciliary body, and Choroid)
Retina

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63
Q

What part of eye absorbs drugs?

A

conjunctiva!

-also is the pink part of pink eye!

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64
Q

The iris DILATOR muscles are _ innervated by the ophthalmic division of CN _, which dilates the _.

A

sympathetically
CN V
pupil

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65
Q

The iris SPHINCTER and ciliary muscles are innervated by the _ nervous system via CN _, causing pupil constriction or _

A

parasympathetic
CN III
miosis

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66
Q

Posterior to the iris is the _ _ which produces _ _

A

ciliary BODY
aqueous humor

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67
Q

Ciliary muscles adjust the shape of the _ to accommodate _ at various distances

A

lens
focus

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68
Q

The conjunctiva is where the tendons of _ muscles insert, and controls _ of light into the eye

A

rectus
refraction

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69
Q

What supplies nutrition to the outer part of the retina?

A

choriocapillaris (makes up choroid which is a network of small vessels and capillaries)

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70
Q

Parts of posterior segment of eye:

A

VITREOUS Humor, Retina
-neurosensory membrane, converts light into electric signals the optic n sends to brain

Macula
-oval, pigmented area in center of retina/central and high acuity vision

Root of optic N

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71
Q

Parts of anterior segment of eye:

A

2 chambers:

Anterior
behind cornea, filled with aqueous humor or vitreous humor

Posterior
Lens - refracts light thru cornea and pupil to focus image on the retina

**both chambers are separated by the iris and communicate via the pupil

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72
Q

6 extraocular muscles are made up of:

A

4 rectus muscles-delineate the retrobulbar cone
-superior, inferior, lateral, medial rectus

2 oblique muscles
-superior and inferior oblique

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73
Q

Explain the pyramidal shape of the orbit cavity.

A

apex = posterior part
base= anterior opening

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74
Q

How can a retinal detachment/tear occur?

A

vitreous humor can pull on the retina
-diabetic retinopathy= neovascularization of retina-> retinal detachment

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75
Q

What regulates thickness of lens?

A

ciliary muscle

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76
Q

Purpose of lacrimal gland:

A

-maintain moist anterior surface of globe, drains into nose below and can be blocked

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77
Q

What supplies blood to the eyE?

A

branches of internal and external carotid arteries

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78
Q

What drains blood from the eye?

A

anastomoses of superior and inferior ophthalmic veins, mainly the central retinal vein, draining blood into the cavernous sinus

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79
Q

Average rate of aqueous humor production:

A

2mcL/ min

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80
Q

Sensory innervation of orbit and globe:

A

Frontal and nasociliary branches of Ophthalmic nerve (1st branches CNV)

Infraorbital and maxillary nerve (2nd branch of CN V)
-part of floor of orbit

Optic Nerve (CN II)
-sends info from the retina

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81
Q

Motor innervation of orbit and globe:

A

**Trochlear (CN IV)
-superior olique m

Abducens (CN VI)
-lateral rectus m

Oculomotor (CN III)
-extraocular m

Branch of CN III
-motor root of ciliary ganglion-> sphincter of pupil and ciliary m**

Facial (CN VII)
-functions in blinking/closing eye

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82
Q

Superior rectus m
-innervation
-function

A

CN III

Elevation

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83
Q

Inferior Rectus m
-innervation
-function

A

CN III

Depression

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84
Q

Medial Rectus m
-innervation
-function

A

CN III

ADDuction

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85
Q

Inferior Oblique m
-innervation
-function

A

CN III

elevation, ABDuction, MEDIAL rotation (extorsion)

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86
Q

Superior Oblique m
-innervation
-function

A

CN IV

depression, ADDuction, EXTERNAL rotation (intorsion)

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87
Q

Lateral Rectus m
-innervation
-function

A

CN VI

ABDuction

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88
Q

Zygomatic branch of facial nerve (CN VII)
-upper branch innervates

A

frontalis m and upper lid

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89
Q

Zygomatic branch of facial nerve (CN VII)
-lower branch innervates

A

orbicularis m of lower lid

90
Q

Which nerve supplies most of the muscles that MOVE the eye?

A

CN III Oculomotor

91
Q

Which nerve provides a majority of sensory innervation to the orbit and globe?

A

Trigeminal nerve (CN V)
3 divisions:
V1: ophthalmic
V2: maxillary
V3: mandibular

92
Q

Which nerve carries SENSORY information from the retina?

A

CN II Optic n

93
Q

Aqueous Humor Flow
1. 2/3 is made in _ chamber, by the _ body.
2.This flows from the posterior chamber into the anterior chamber via the _ aperture
3. This mixes with the other 1/3 which is made by _ filtration from vessels on anterior surface of _.
4. Eventually flows to the venous system and into the _ _ _, then the _ atrium
5. An obstruction between the eye and _ atrium would then increase _ _ _.

A
  1. posterior, ciliary
  2. pupillary
  3. Passive, iris
  4. superior vena cava, right atrium
  5. right, intraocular pressure (IOP)
94
Q

Normal IOP range
Abnormal IOP is:

A

Normal= 10-21.7 mmHg

Increased IOP = >22mmHg

95
Q

Most important determination of IOP=

A

aqueous humor production/elimination

-also external pressure on eye and scleral rigidity

96
Q

What reflex causes dysrhythmias during eye surgery? What are its 2 limbs?

A

Trigeminovagal Reflex AKA Oculocardiac Reflex

AFFerent= orbital contents, ciliary ganglion, ophthalmic division of CN V (floor of 4th ventricle)

EFFerent= Vagus n to heart(via visceral motor nucleus in reticular formation; decreases SA node output)

97
Q

What WORSENS the trigeminal nerve reflex?

A

-hypoxia
-hypercarbia
-light anesthesia
acidosis

98
Q

What triggers the oculocardiac/ trigeminovagal reflex?

A

-eye block (also lessens chance of it once blocked)
-ocular pain (postop)
-ocular trauma
-manipulating orbital apex
-ocular manipulation
-direct pressure on globe
-traction of extraocular m (esp medial rectus, but all can)

99
Q

Treatment of oculacardiac/ trigeminovagal reflex:

A

-tell surgeon to stop manipulation - number one
-deepen anesthetic, support ventilation
-brady? -> atropine 0.02mg/kg ~1-2mg if brady significant, if mild -> glyco 0.2-0.4mg IV
-persistent brady? - > infiltrate rectus muscle with LA
-reflex will fatigue after a while

100
Q

Increased IOP during anesthesia can cause:

A

permanent vision loss

101
Q

Which 2 fluids regulate IOP?

A

-aqueous humor
-choroidal volume

102
Q

What is a possible effect of local anesthetic injection to treat OCR?

A

act of injecting LA can cause reflex

103
Q

When should glyco be used in OCR?

A

if pt is brady ~20% from baseline (HR drop from 70->50)

GIVE: 0.2-0.4mg IV

104
Q

When should atropine be used in OCR?

A

if pt is severely brady or asystole

GIVE: 0.02mg/kg OR 1-2mg IV

105
Q

Increasing already elevated IOP can cause:

A

glaucoma

106
Q

Penetration of globe when IOP is high causes:

A

ruptured blood vessel -> hemorrhage

107
Q

When is IOP higher, sleep or awakening, why?

A

awakening
-vascular congestion, pressure on globe from closed eyelids and dilated pupils

108
Q

Sclerosis is associated with _ scleral compliance and _ IOP. (increases/decreased)

A

decreased
increased

109
Q

T/F It is appropriate to pretreat all pts having eye surgery with atropine to avoid OCR.

A

False
-just kids (more common)
0.02mg/kg Atropine or 0.01mg/kg Glyco

110
Q

Relevant neural paths of OCR:

A

any of the branches of trigeminal nerve (afferent) and the vagus nerve (efferent)

111
Q

An 82-year-old patient presents for cataract surgery with placement of glaucoma tube shunts. Baseline HR 60s and BP 130s/80s. Ten minutes into the procedure the patient’s heart rate decreases from 67 bpm to 28 bpm. You ask the surgeon to relieve pressure on the eye. After 30 seconds, the patient is asystolic. What is the most appropriate next step?

A

Atropine 0.2 mg/kg
Consider 1 mg IVP, incrementally may increase (clinically 1-3 mg IV)
Treatment steps:
Stop- HR should return in 20 seconds
Ensure adequate depth and ventilation
Atropine/glycopyrrolate
Consider regional infiltration

112
Q

An 82yo is presenting for cataract surgery with placement of glaucoma tube shunts. Ten minutes into the procedure the patient’s heart rate decreases from 67 bpm to 28 bpm. You ask the surgeon to relieve pressure on the eye. After 30 seconds, the patient’s heart rate is 42 bpm. What is the most appropriate next step?

A

Glycopyrrolate 0.2 mg IV
Pt experiencing sustained bradycardia as opposed to asystole

113
Q

What increases IOP? (everything lol)

A

-Impaired aqueous drainage (glaucoma)
-Increased choroidal blood volume (vessel volume)
-Compression of the eye, damage to optic n
-Laryngoscopy/intubation/ emergence
-Hypoxia/ hypercapnia
-HTN
-SUX!
-PEEP > 15cmH2O
-Coughing, straining, vomiting (30-40 mm Hg)
-Ocular blocks (5-10 mm Hg)
-Cardiac contraction (1-2 mmHg)
-Positions- supine, prone, Trendelenburg
-Blinking (5-10 mm Hg)
-Forceful lid squeeze (70 mm Hg)

114
Q

Any maneuver that increases _ pressure, increases IOP.

A

venous

115
Q

Hemodynamic factors and their effect on IOP

A

Elevates IOP:
-elevated CVP
-elevated PaCO2(hypoventilation)
-elevated ABP

Decreases IOP:
-decreased CVP
-decreased PaCO2 (hyperventilation)
-decreased ABP
-decreased PaO2

116
Q

Medication effects on IOP

A

IA
-Volatile anesthetics = decrease
-N2O = +/-

IV agents
-Prop = decrease
-Benzos = +/-
-Ketamine = +/-
-Opioids = decrease
-Mannitol = decrease
-Acetazolamide (Diamox) = decrease

NMBD
-Sux = INCREASES!!!!
-NDMR = +/-

117
Q

How does Sux increase IOP?

A

prolonged contraction of EO muscles, fasciculations, choroidal vascular dilation and relaxation of orbital smooth muscle

2 sources of info:
-increases 5-10mmHg for 5-10 min
OR
-increases by 9mmHg for 1-4 mins up to 7min

118
Q

How many mL in one eye drop?

A

1/20 mL

119
Q

When stimulation of OCR is stopped, HR should return in _ sec

A

20 sec

120
Q

Most significant factor on formation of aqueous humor is difference in osmotic pressure between _ _ and _

A

aqueous humor and plasma

121
Q

Most significant factor controlling aqueous humor outflow is the diameter of the _ space in the _ meshwork

A

Fontana space
trabecular meshwork

122
Q

Pupil dilation _ (increase/decreases) IOP. How?

A

increases
-volume within fontana space narrows, increasing resistance of outflow
-> ocular HTN ->glaucoma

123
Q

Open angle vs closed angle glaucoma

A

open angle = from increased IOP from sclerotic trabecular tissue leading to decreased drainage

closed angle= obstruction from either displaced iris on posterior cornea or swelling of crystalline lens

124
Q

Can glaucoma pts have atropine? What about scopalamine?

A

Atropine yes (ONLY VIA IV!)
Scopolamine no, causes more mydriasis = increasing IOP

125
Q

Which kind of surgery is known to cause the most increase in IOP?

A

robotic lap cases
-> steep trend and CO2 insufflation

126
Q

What can occur if a pt coughs during surgery with their eyes open?

A

-hemorrhage and disconcerting loss of vitreous

127
Q

Intraop factors to avoid increasing IOP in glaucoma pts:

A

-over hydration
-prone
-trend for too long
-hypercapnia
-neck constriction
-high level insufflation

128
Q

What is visual field “wipe out” in glaucoma pts?

A

after surgery a small percent of these pts have significant vision loss
-cause is not determined but may be due to poor perfusion, optic nerve injury/pressure, compression device

129
Q

Procedure for infantile glaucoma=

A

goniotomy

MUST HAVE GA

130
Q

Most commonly performed filtering procedure in adults =

A

trabeculotomy
-removes limbic tissue blocking aqueous humor drainage, using tubes or shunts
-adults can have a Retrobulb or Peribulb injection and if needed a facial n block

131
Q

Patho of diabetic retinopathy (DR)
1. Chronic _ cause _ abnormalities.
2. The _ abnormalities cause impaired _ of blood flow
3. This then causes retinal _ and ischemia
4. _ and _ proteins also accumulate.
5. Neovascularization occurs and this could eventually cause retinal _

A
  1. hyperglycemia, vascular
  2. vascular, autoregulation
  3. hemorrhage
  4. Sorbitol and glycated proteins
  5. retinal detachment
132
Q

2 kinds of retinal detachment:

A

Rhegmatogenous (tear) (more common)
or
Non-rhegmatogenous
-tractional
-exudative

133
Q

Retinal Detachment
s/s

A

-floaters
-flashing lights
-vision loss
-shadows/clouds
-curtain like blackness

134
Q

If N2O is being used in retinal detachment surgery, must be turned off for _ - _ min before injecting _ _ to prevent expansion and increased IOP.

A

15-30 min
sulfur hexafluoride

135
Q

If pt needs surgery within 2 wks of retinal detachment surgery, which agent is contraindicated?

A

N2O

136
Q

Purpose of sulfur hexafluoride in retinal detachment surgery:

A

tamponades retina onto the choroid layer is detached from

137
Q

Predisposing factors for retinal detachment:

A

-old age
-diabetic retinopathy (HTN and DM)
-prior eye surg
-vitreal disease
-myopia

138
Q

Small incisionextracapsular cataract extraction, also known as_, is the preferred method of modern cataract extraction

A

phacoemulsification

-small incision of 3-4mm, lens nucleus is broken apart and sucked out, new lens implant is placed

139
Q

How is anesthesia given for cataract cases?

A

usually MAC and topical or regional

140
Q

2 major preop/ intraop considerations for strabismus surgery:

A

these pts may also have myopathic condition (MH!!!)

-oculocardiac reflex easy to trigger!

141
Q

Major postop consideration for strabismus surgery:

A

PONV is very common, get several agents on board to prevent

142
Q

T/F All pts having strabismus surgery can have regional anesthesia and TIVA

A

False!
kids need GA
adults can have TIVA + regional

-most ppl prefer GA tho (give propofol, remifentanil, zofran, decadron, and non-opiate pain relief)

143
Q

Surgical correction of strabismus is repositioning of _ _

A

extraocular muscles (EOMS)

144
Q

T/F topical anesthesia is ok for retinal detachment cases?

A

false
-not ok for posterior chamber surgery

-better for fast surgeons and cases not requiring akinesia of eye (glaucoma or cataracts-anterior cases!)

145
Q

2 main kinds of topical anesthetic for eye cases:

A

0.5% Proparacaine (Proxymetacaine) drops Q 5 mins, 5 times, then give LA gel, Lidocaine + 2% Methyl-cellulose
-common for cataract surgery

Ophathalmic 0.5% Tetracaine
-more common

146
Q

CN VII Oculi Block/ Van Lint Method
-which muscle blocked
-how many insertion points
-how many mL

A

prevents blinking/squinting, part of the complete immobilization of eye

blocks: orbicularis oculi

insertions: 3

mL: 1mL LA in 1st spot, then 2-3mL in 2nd and 3rd

147
Q

Analgesia of the _ precedes _ of the eye usually

A

globe
akinesia

148
Q

Which block takes longer to work, retrobulbar or peribulbar?

A

Peribulbar block = 10 min
Retrobulbar = 2 min

149
Q

When considering an ocular block for a pt on anitcoags, which methods are safest?

A

Sub-Tenons or topical anesthesia
-minimize hemorrhage risk

150
Q

Which ocular hemorrhage is more threatening to the pt, arterial or venous?

A

arterial-from retorbulbar

151
Q

T/F Retrobulbar arterial hemorrhages result in a non-compressive hematoma and can wait to be dealt with after the surgery

A

false!
-emergent, tell surgeon and/or ophthalmologist, stop case, may need rapid decompression(cantholysis) to prevent permanent blindness, constant monitoring of IOP

152
Q

Which complication of ocular blockade results in seizures or arrest? How?

A

Intra-arterial injections

MOA:
-caused by forceful injection into ophthalmic artery causing retrograde flow of LA into internal carotid (LAST)
or
-forceful injection directly into optic nerve sheath
-> sending LA to midbrain structures

153
Q

Retrobulbar hemorrhage s/s=

A

redness of eyelid or conjunctiva

increasing proptosis pain

increased IOP

direct trauma to artery or vein

154
Q

Oculocardiac reflex
-s/s
-MOA

A

s/s: brady, arrhythmias, asystole

MOA: CN V trigeminal (afferent arc) to floor of 4th ventricle with efferent arc via vagus nerve

155
Q

Unintended intra-arterial LA injection treatment:

A

-patent airway with O2
-stop seizure with small dose benzo, prop, or barbiturate

156
Q

Unintended subarachnoid injection (total spinal) treatment:

A

-O2
-vasopressors
-intubation/vent if needed, spinal should wear off in few hrs)

157
Q

T/F Requirements for eye surgery include total akinesia and lowered IOP

A

false
-new surgical techniques permit these

158
Q

2 largest causes of eye injury claims comes from:

A

-pt moving during ophthalmic surgery
-needle trauma from orbital blocks

159
Q

Which orbital block has higher risk of complications, retrobulbar or peribulbar?

A

retro

160
Q

Which orbital block injects into the cone of the eye?

A

retrobulbar

161
Q

Retro and Peribulbar blocks require which position for the pt?

A

supine with “primary gaze”

162
Q

Retro and Peribulbar blocks are appropriate for which kinds of cases?

A

-corneal
-ANTERIOR
-lens

163
Q

What is the volume difference in LA used in retro and peribulbar blocks?

A

R: 1.5-5mL
P: 4-6mL (up to 12mL)

164
Q

Retrobulbar Block
-goal

A

-anesthesia
-akinesia (not total)
-abolishment of oculocephalic reflex (blocked eye won’t move when head is turned)

165
Q

Retrobulbar block
-target

A

-ciliary nerves
-ciliary ganglion
-CN II(maybe)
-CN III
-CN IV
-CN VI

will not block CN VII

166
Q

Retrobulbar Block Procedure
1. Get _ G _ tip needle
2. Draw up _ - _ mL of LA
3. Insert perpendicularly between lateral _ and medial _ of _ orbital rim.
4. Aim _ and _
5. Walk to depth of _ - _ mm
6. _ first, then inject

A
  1. 25G, blunt
  2. 1.5-5mL
  3. 1/3, 2/3, inferior
  4. cephalad and medially
  5. 25-35mm
  6. Aspirate
167
Q

Retrobulbar Block
-usable types of LA

A

-Lido 2%
-Bupivacaine 0.75%
-Ropivacaine 0.75%

168
Q

Retrobulbar Block
-position

A

sitting or supine
-with/without sedation (usually brief, deep sedation)
-pt keeps eyes neutral

169
Q

A retrobulbar block has _ (more/less) insertion points and _ (more/less) volume administered compared to peribulbar blocks.

A

less
less

-1 insertion point. 1.5-5mL volume given for Retro

170
Q

Which ocular muscle avoids being blocked with a Retrobulbar block?

A

Superior Oblique

-also orbicularis oculi bc CN VII isn’t blocked either

171
Q

Pt receiving retrobulbar block for ophthalmic procedure…what are some drugs that may be used to sedate the patient during injection?

A

Propofol
Etomidate
Fentanyl/Versed
-consider pt needs
-want fast on/off

172
Q

Postretrobulbar block apnea syndromeis probably due to injection of local anesthetic into the _ _ _, with spread into the cerebrospinal fluid

A

optic nerve sheath

173
Q

Retrobulbar Block
-complications

A

retrobulbar hemorrhage
perforation of the globe
optic nerve injury
intravascular injection with resultant convulsions(RESULTS IN SEIZURES/CONVULSIONS RIGHT AWAY!!)
oculocardiac reflex
trigeminal nerve block
respiratory arrest
acute neurogenic pulmonary edema

174
Q

Retrobulbar block
-Contraindication

A

Age< 15
Procedures lasting longer than 90-120 minutes
Uncontrolled cough or tremors
Disorientation or mental impairment
Excessive anxiety or claustrophobia
Language barrier or deafness
Coagulopathies
Perforated globe

175
Q

Peribulbar block
-injection site

A

Extraconal space, needle doesn’t need to penetrate cone

1st: INFERIOR AND TEMPORAL REGIONS, same as retro, but less cephalad and medial

2nd: between medial 1/3 and lateral 2/3 of ORBITAL ROOF EDGE

176
Q

Which orbital block has a “pop” to it?

A

Retro- pierces into the cone

177
Q

Peribulbar Block
-target

A

ciliary nerves
CN III
CN VI

-does NOT block CN II

178
Q

Peribulbar block
-position

A

supine

179
Q

Peribulbar Block
-pros

A

There is less potential for intraocular or intradural injection since LA is deposited outside of muscular cone
Less risk of globe perforation
Less risk of intravascular injection
Risk of hemorrhage decreased
Risk of injury to optic nerve decreased
No need for additional lid block
Technically easier to place
-PREFERRED METHOD DUE TO LESS RISK

180
Q

Peribulbar Block
-cons

A

More difficult to get a complete, dense block
Slower onset
Risk of ecchymosis

181
Q

Sub-Tenon Block
-injection site

A

episcleral space via inferonasal conjunctival fornix
-between tenons capsule and sclera, diffuses from this space and blocks sensory + motor neurons

182
Q

Sub-Tenon Block
-goals

A

Analgesia: low volumes (3-5mL) superficial
Akinesia: high volumes (8-11mL) deeper

183
Q

Sub-Tenon Block
-complications

A

less common, shorter, duller needles

-Globe perforation
-hemorrhage
-cellulitis
-permanent visual loss
-Local anesthetic spread into cerebrospinal fluid

184
Q

GA considerations for eye cases:

A

Antiemetics

Smooth induction/intubation

Avoid oculocardiac reflex; know how to treat if it happens

Motionless field

Smooth extubation

Consider LMA

**Requires OET: vitrectomy, trauma to eye, vitreoretinal procedures

-Airway will be away from you**

-Nitrous oxide??

185
Q

Postop considerations after eye cases:

A

-pain with non-cataract surgeries

-multimodal pain mgmt (NSAIDs, tylenol, gabapentin)

-treat PONV! -very common

186
Q

Open eye injury
-risks/complications to avoid

A

-avoid increasing IOP at induction/extubation

-aspiration (usually full stomach if trauma)

-avoid regional bc increases IOP with injection

-avoid trending bed

-very carefully mask ventilate-watch eyes!

187
Q

Open eye injury
-best anesthesia method + why

A

GA is safest

  • smooth IV induction (avoid coughing/bucking)

-RSI with high dose Roc = 1.2mg/kg

**-if diff airway, get ophthalmologist to come and CAREFULLY do awake FOB

-consider narcotic and lidocaine for extubation or deep extubation is no asp risk**

188
Q

When to use GA for eye cases:

A

-long case

-pt fears

-pediatrics

-cognitive impairment/ inability to communicate

-hearing loss

-trauma/ open eye

-certain pt conditions (dementia, deafness, restless leg, OSA -debatable, tremors, claustrophobia)

-INABILITY TO LAY FLAT!!!

189
Q

MAC vs GA examples
65-year-old healthy patient undergoing blepharoplasty?

A

MAC
-pt must be able to communicate for this type of case

190
Q

MAC vs GA examples
88-year-old patient with CHF, Afib, DM undergoing extracapsular cataract extraction (ECCE) with IOL placement?

A

If they can lay flat and talk for 0.5 -1hr then MAC, if not, then GA

191
Q

MAC vs GA examples
72-year-old patient with tremors undergoing ectropion repair?

A

Probably GA
-tremors = bad

192
Q

MAC vs GA examples
27-year-old healthy patient undergoing orbital tumor removal?

A

GA
-emergent

193
Q

MAC vs GA examples
45-year-old patient with HTN and DM undergoing orbital fracture repair

A

GA
-this is a trauma/emergent

194
Q

MAC vs GA examples
58-year-old patient with OSA undergoing ptosis repair?**

A

“This is a nightmare situation”-Holly

MAC!

-pt needs to communicate for this kind of case but they have OSA, give sedation during LA but wake up and try to keep comfortable without obstructing

195
Q

MAC considerations for eye cases

A

-head at top edge of table to avoid back and neck pain

-support head on headrest to prevent movement

-head above or at level of heart, avoid venous pressure in eye leading to hemorrhage

-tape head to table to prevent sudden movemnt

-restrain arms to pts side to prevent sudden movement

-place drapes so O2 doesn’t get trapped underneath

-turn off O2 when cautery/laser is in use

-<30% FiO2 goal

196
Q

Can a pt with cataracts receive orbital blocks?

A

no, use topical

197
Q

Ocular blocks last usually _ - _ hrs

A

2-3hrs

198
Q

Sedation goal for pt receiving eye block:

A

deep but not too deep

awake but not talking

199
Q

T/F eye drops absorb slowly compared to IV/SQ injections

A

false,
its BETWEEN the two

200
Q

1 eye drop = _ mL

A

1/20 mL

-so 10% phenylephrine drop contains 5mg of phenylephrine (a shit ton compared to IV dose of 0.05-0.1mg)

201
Q

Echothiophate (phospholine iodide) eye drops prolong action of _

A

sux

202
Q

_ eye drops cause bradycardia, CHF, and BRONCHOSPASM

A

Timolol

203
Q

Acetazolamide is often used in _ cases and can cause _ when given too quickly IV

A

glaucoma

confusion

204
Q

Ophthalmic Meds:
Acetylcholine
-MOA
-use

A

MOA: cholinergic agonist

uses: miosis

205
Q

Ophthalmic Meds:
Acetylcholine
-s/e

A

brady

brochospasm

HoTN

206
Q

Ophthalmic Meds:
Acetazolamide
-MOA
-uses

A

MOA: carbonic anhydrase inhibitor

uses: decreases IOP, glaucoma

207
Q

Ophthalmic Meds:
Acetazolamide
-s/e

A

confusion

drowsiness

hypoK+ + hypoNa+

met. acidosis

altered liver function tests

polyuria

renal failure

208
Q

Ophthalmic Meds:
Atropine
-MOA
-uses

A

MOA: anticholinergic

uses: mydriasis

209
Q

Ophthalmic Meds:
Atropine
-s/e

A

dry mouth

dry skin

fever

agitation (central anticholinergic syndrome)

210
Q

Ophthalmic Meds:
Epinephrine
-MOA
-uses

A

MOA: alpha, beta agonist

uses: mydriasis, decrease IOP

211
Q

Ophthalmic Meds:
Epinephrine
-s/e

A

HTN

tachycardia

Vent arrhythmias

212
Q

Ophthalmic Meds:
Mannitol
-MOA
-uses

A

MOA: osmotic diuretic

uses: decrease IOP

213
Q

Ophthalmic Meds:
Phenylephrine
-MOA
-uses

A

MOA: alpha adrenergic agonist

uses: mydriasis, vasoconstriction

214
Q

Ophthalmic Meds:
Phenylephrine
-s/e

A

HTN

215
Q

Ophthalmic Meds:
Tamulosin
-MOA
-uses

A

MOA: alpha ANTagonist

uses: benign prostatic hyperplasia (BPH)

216
Q

Ophthalmic Meds:
Tamulosin
-s/e

A

floppy iris syndrome-tell surgeon, they may make pt stop taking this

-nothing anesthesia can do really

217
Q

Ophthalmic Meds:
Timolol
-MOA
-uses

A

MOA: beta 1+2 ANTagonist

uses: glaucoma

218
Q

Ophthalmic Meds:
Timolol
-s/e

A

bradycardia

bronchospasm

CHF exacerbation

219
Q

How does hypothermia decrease IOP

A

-initial increase due to increased viscosity of aqueous humor

-decreases the formation of aqueous humor and vasoconstriction to decrease IOP

220
Q

How to decrease systemic absorption of eye drops:

A

occlude nasolacrimal duct by pressing on inner canthus of eye

221
Q

CN VII block can cause which airway issues?

A

Unilateral vocal cord paralysis

222
Q

What is OPP?

A

ocular perfusion pressure = MAP - IOP

dangerously low OPP level = < 50mmHg

223
Q

Which CN gives sensation to eye?

A

CN V - ophthalmic branch

NA 1 (31 decks)

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