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931: Advanced Principles of Anesthesia I > Ophthalmic part 2 > Flashcards

Ophthalmic part 2 Flashcards

1
Q

Local anesthetics for eye surgery are

A

most often placed by surgeon

toxicity is rare but may occur

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2
Q

Topical agents used for eye surgery include

A 
tetracaine (most common)
proparacaine
bupivacaine
lidocaine
cocaine
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3
Q

Topical eye medications enter bloodstream through

A

outer eye membrane & lacrimal apparatus

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4
Q

Measures to reduce the amount of topical eye medication that enters the bloodstream include:

A

close eyes for 60 seconds after drops instilled to encourage absorption by eye
avoid blinking
block tear outflow canal (place index finger over medial canthus)

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5
Q

The most frequently performed intraocular procedures include

A

cataract & vitreoretinal surgeries

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6
Q

______ for cataract is effective in providing adequate analgesia

A

topical anesthesia

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7
Q

Ocular regional anesthesia is the most common and effective way to consistently

A

produce analgesia & akinesia of the eye and eyelids

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8
Q

Ocular local anesthesia includes

A

peribulbar block & retrobulbar block

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9
Q

To provide ocular regional anesthesia, one may block ______ outside of the eye

A

anesthetize multiple cranial nerves (III, IV, V, VI, or VII)
orbital epidural space
facial nerve block

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10
Q

A peribulbar block is injection of local anesthesia

A

outside** the muscle cone

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11
Q

Peribulbar block provides

A

analgesia & akinesia of the eye

relatively low complication rate

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12
Q

Disadvantages of peribulbar block includes:

A 
large volumes injected (6-8 mL)
may increase IOP
slower onset of action (5-10 minutes)
-possible perforation of globe
-vertical diplopia (myotoxicity from local anesthesia)
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13
Q

To perform the peribulbar block,

A

have the patient look straight ahead- avoid vasculature & optic nerve
use dull, short-beveled 25-27 gauge, 22 mm needle
insert needle in lateral aspect of the inferotemporal quadrant & superiornasal
do not insert beyond 25 mm or pierce muscle cone
ASPIRATE before slowly injection
6 mL of LA
lidocaine + bupivacaine

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14
Q

A retrobulbar block is injection of local anesthesia

A

INSIDE** the muscle cone

provides analgesia & akinesia of the eye

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15
Q

The ______ block has a higher complication rate

A

retrobulbar block

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16
Q

Describe how to perform the retrobulbar block.

A

insert 25 gauge needle through lower lid at the junction of the lateral third & medial 2/3 of the inferior orbital edge
advance 25-35 mm toward apex of orbit (19-31 mm safest)
ASPIRATE and inject 2-5 mL LA
lidocaine & bupivacaine most common

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17
Q

Complications of the retrobulbar block include

A 
complications occur in 1:500 blocks
trauma to optic nerve
vision loss
retrobulbar hemorrhage
globe perforation
oculocardiac reflex
brainstem anesthesia (injection into optic nerve sheath)
intravenous or intra-arterial injection
seizure
respiratory or cardiac arrest
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18
Q

Complications of the retrobulbar block usually occur within

A

15 minutes after block

standard monitors, emergency equipment, & vigilance

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19
Q

Contraindications to the retrobulbar block include:

A

bleeding disorders, anticoagulation, extreme myopia, open eye injury

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20
Q

A sub-Tenon’s (Episcleral) block is local anesthetic placed into

A

potential space between Tenon’s capsule & the sclera

inferonasal conjunctival fornix is most commonly used

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21
Q

Describe how to perform Sub-Tenon’s block.

A

direct needle posteriorly following curve of globe
superficial injection allows LA to spread circularly around scleral portion of globe (3-5 mL)
larger volume (8-11 mL) allows spread to extraocular muscle sheaths
Deep injection- posterior intra & extraconal spaces is most common

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22
Q

A facial nerve block may be performed to

A

prevent excessive blinking during eye surgery

periocular branches of the facial nerve

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23
Q

30% of eye injury claims are due to

A

patient movement during ophthalmic surgery- blindness was the outcome in all cases

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24
Q

Describe pediatric considerations for ophthalmic surgery

A

assess for congenital, metabolic, MSK, and malignant hyperthermia

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25
Q

Describe the elderly considerations for ophthalmic surgery.

A

HTN, DM, CHF, pulmonary disease, mental status, arthritis, polypharmacy, cardiac disease

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26
Q

Most eye operations can be performed under

A

regional anesthesia & sedation
-same standard of care
NPO status is even more important

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27
Q

Unique preoperative considerations include:

A

can patient lie flat, lie still, claustrophobia, etc.?
make sure patient knows what to expect for anesthetic
considerations for GETA
general anesthesia for infants and young children
temperature, fluids, & foley

28
Q

Indications for general anesthesia include:

A

pediatric patient, patient’s lack of cooperation, severe claustrophobia, inability to communicate, inability to lie flat, open-eye injuries, procedures with durations greater than 2 hours

29
Q

Disadvantages of general anesthesia for eye surgeries include

A

N/V, retching/bucking, increased intraocular pressure, aspiration, complications secondary to other medical problems, time & expense

30
Q

For sedation for blocks consider use of

A

short-acting agents to provide amnesia, analgesia, & immobility
-prevent cardiac or respiratory side effects

31
Q

Intraoperative medications for eye procedures include

A

fentanyl, alfentanil, remifentanil, midazolam, propofol, dexmedetomidine
-consider synergistic effects, dosing for elderly/pediatrics, circulation time

32
Q

Describe intraoperative management for eye procedures:

A 
unnecessary to maintain sedation if block is adequate
OR table turned 90 or 180 degrees
standard monitors
oculocardiac reflex
temperature 
fluids
"Light" GA for little stimulation
hypotension
oxygen & cautery
risk of corneal abrasion, retinal artery occlusion
33
Q

Describe postoperative management for eye procedures:

A

PONV
postop eye pain is unusual- corneal abrasion & acute intraocular HTN (treat with mannitol/acetazolamide)
elderly patients with history of MI are at increased risk for ischemic events even under LA- consider preop beta-blockers

34
Q

Common eye procedures include

A

strabismus repair, foreign body removal, conjunctival flap, corneal transplant, trabeculectomy, penetrating eye injuries, cataract, ptosis surgery, eyelid reconstruction, blepharoplasty, retinal detachment repair (scleral buckling), vitrectomy, ophthalmic oncology

35
Q

Strabismus is an

A

ocular misalignment

most common ophthalmic condition requiring surgical repair in children

36
Q

Intervention for strabismus should occur before

A

4 months to allow normal stereoscopic visual development

37
Q

Strabismus surgery

A

lengthens/shortens ocular muscles to straighten eyes & allow binocular vision

38
Q

Strabismus is performed under

A

GA
minimal EBL
table turned

39
Q

With strabismus concerns include

A

oculocardiac reflex, increased risk of MH, PONV

40
Q

Describe the oculocardiac reflex with strabismus

A

increased PaCO2 shown to decrease OCR during strabismus

stop stimulation, administer anticholinergics, LA infiltration

41
Q

Describe increased risk of MH with strabismus.

A

associated with underlying myopathy- higher risk of MH
avoid triggers
monitor: temp, EKG, EtCo2, muscle rigidity
ABG: low PaO2, high PaCO2, hyperkalemia, acidosis
Dantrolene 2.5 mg/kg IV up to 10 mg/kg

42
Q

PONV with strabismus is due to the

A

ocular-emetic reflex

  • possible disruption of surgical repair
    prevention: hydration, minimize opioids, avoid N2O, propofol, La infiltration near extraocular muscle, antiemetics
43
Q

Penetrating eye injury concerns include:

A

full stomach precautions
aspiration risk
prevent increase in IOP- succinylcholine (increases within 1 minute, peaks with 9 mmHg), coughing
open globe- succinylcholine risk vs. benefit; laryngoscopy & intubation increases IOP, consider non-depolarizing NMB for RSI

44
Q

Open globe with a full stomach is an

A

EMERGENCY SURGERY WITH GA**

45
Q

The do’s and don’ts to prevent aspiration with open globe include:

A

do NOT attempt to evacuate contents using NGT preop
DO administer metoclopramide IV, H2 antagonists (ranitidine), non-particulate antacid prior to induction
-Do NOT attempt regional anesthesia (LA injection will increase IOP)
-DO attempt RSI using cricoid pressure avoiding PPV
-DO extubate awake, spontaneously breathing, head turned to side

46
Q

Preventing increase in IOP with open globe includes:

A 
avoid direct pressure on eye
avoid Trendelenburg position
avoid regional anesthesia
avoid increases in CVP
avoid drugs that increase IOP
avoid agitation in young children
47
Q

Anesthesia complications for eye surgeries include

A 
retrobulbar hemorrhage
globe puncture
optic nerve sheath trauma
intravascular injection
ocular ischemia
extraocular muscle palsy & ptosis
facial nerve blocks
oculocardiac reflex 
corneal abrasion
central retinal artery occlusion (prolonged pressure)
48
Q

Retrobulbar hemorrhage results from

A

trauma to an orbital vessel

moves eyeball forward

49
Q

Venous hemorrhages have

A

slow onset, while arterial hemorrhage has rapid onset & pronounced proptosis

50
Q

Lateral canthotomy may be indicated if the hemorrhage is

A

not resolved by digital pressure

  • increase orbital space by cutting the lateral canthus
  • reduces orbital pressure that results from hemorrhage
  • place hemostat in temporal direction along lateral canthus 4-6 mm and clamp hemostat
  • use scissors to incise the crush marks left by hemostat
  • control local bleeding
51
Q

Globe puncture can be due to

A

sharp and dull needles both reported to have penetrated the eye during injections
globe can burst apart from IOP caused by injection

52
Q

Risks for globe puncture include

A

myopic eye, scleral thinning, scleral buckling, bulging of sclera

53
Q

Prevention of globe puncture includes

A

avoid supranasal position of gaze
direct needle away from axis of globe during insertion
insert needle slowly with bevel towards globe
never forcefully inject LA
use modified techniques

54
Q

Symptoms of globe puncture include:

A

increased resistance to injection
dilation/paralysis of pupil
increased IOP
hemorrhage

55
Q

The optic nerve sheath surrounds

A

the optic nerve

56
Q

The optic nerve sheath is composed of

A

meninges of brain

  • outer sheath contains dura mater
  • inner sheath consists of arachnoid & pia mater
  • subarachnoid space contains CSF and is continuous with optic chiasm
  • dura splits into two layers at optic foramen
57
Q

When evaluating for optic nerve sheath trauma,

A

observe contralateral pupil before block
if contralateral pupil constricted–> dilated after block–> assume subarachnoid/subdural injection and prepare for respiratory arrest

58
Q

_______ has been reported after ocular blocks.

A

retinal vascular occlusion or thrombosis

59
Q

Ocular ischemia may be a result of

A

decreased pulsatile ocular blood flow after blocks

optic nerve atrophy reported after regional block or GA

60
Q

Transient symptoms of optic nerve injury include

A

contralateral amaurosis or respiratory arrest; or vascular occlusion/thrombosis which may lead to loss of vision

61
Q

______ may occur secondary to direct nerve trauma.

A

Bell’s palsy

62
Q

Prevention of facial nerve block paralysis includes:

A

avoid large volume LA, avoid Nadbath technique in certain patients, seated/lateral position to protect airway, intubate if airway concerns

63
Q

With paresis of the vagus, glossopharyngeal, and spinal accessory nerves,

A

dysphagia, hoarseness, coughing, and respiratory distress may be seen

  • nerves exit skull 10 mm medial to CN VII
  • LA injected for CN VII block can reach these nerves
  • Unilateral vocal cord paralysis
64
Q

Extraocular muscle palsy is a result of

A

inferior muscle palsy reported after retrobulbar anesthesia

65
Q

Symptoms of extraocular muscle palsy include

A

persistent vertical diplopia

surgical intervention may be indicated

66
Q

Prevention of extraocular muscle palsy includes

A

avoid needle contact with extraocular muscles, avoid deep orbital penetration, avoid angling needle toward visual axis of globe

67
Q

Myotoxicity of LA may cause postoperative

A

diplopia and/or ptosis

931: Advanced Principles of Anesthesia I (22 decks)

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