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Pain Exam 3 > Miller's Pgs x > Flashcards

Miller's Pgs x Flashcards

Miller's Basics of Anesthesia, Chp 31, p. 546-552

1
Q

Sign of impending respiratory arrest

A

dilated pupils

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2
Q

Why do we want to avoid Coughing and bucking in eye procedures?

A

increases venous and intraocular pressure (IOP)

may negatively affect surgical outcome

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3
Q

The eye region’s extensive ____ innervations predispose patients to….

A

parasympathetic

intraoperative bradycardia and asystole

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4
Q

Most ophthalmologic procedures are performed via what anesthetic plan?

A

MAC and some form of regional or topical eye anesthetic

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5
Q

Advantages of ophthalmic regional blocks

A
  • intraoperative analgesia and akinesia
  • suppress oculocardiac reflex (OCR)
  • postop pain management
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6
Q

When to use General anesthesia

A
  • prolonged procedures
  • more invasive orbital procedures
  • unable to be relatively still (neonates, infants, children)
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7
Q

IOP is primarily derived from a balance between …

A

aqueous humor production and drainage

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8
Q

T/F
Any obstruction of venous return from the eye to the right side of the heart can increase IOP

A

True

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9
Q

Aqueous humor is actively secreted from

A

the posterior chamber’s ciliary body

flows through the pupil into the anterior chamber, where it is admixed with aqueous humor

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10
Q

IOP range

A

10 - 22 mm Hg

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11
Q

Sustained increase in IOP during anesthesia can cause

A
  • acute glaucoma
  • retinal ischemia
  • hemorrhage
  • permanent visual loss
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12
Q

Factors That Increase Intraocular Pressure

A
  • substantive increase: Venous congestion in the episcleral veins to the right atrium
  • Trendelenburg positioning or a tight cervical collar before induction
  • Straining, retching, or coughing
  • Hypoxemia and hypoventilation
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13
Q

can readily precipitate an increase in IOP of 40 mm Hg or more.

A

Straining, retching, or coughing during induction

if the globe is open, hemorrhage and expulsion of eye contents may lead to permanent damage to the eye or even blindness

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14
Q

T/F
Arterial hypertension can transiently increase IOP but less than obstructions of venous drainage.

A

True

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15
Q

Hypoxemia and hypoventilation can ____ IOP.
Hyperventilation and hypothermia will ___ IOP.

A

Hypoxemia and hypoventilation = increase

Hyperventilation and hypothermia = decrease

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16
Q

ketamine for eye surgery

A
  • may not increase IOP
  • but causes rotatory nystagmus & blepharospasm
  • less-than-ideal anesthetic
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17
Q

Nondepolarizing vs Depolarizing NMB
effect on IOP

A

NDNMB decreases IOP

  • (If no alveolar hypoventilation)
  • relaxes extraocular muscles

succinylcholine

  • increases by 9 mmHg in 1-4 minutes
  • back to baseline within 7 minutes
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18
Q

What may attenuate the increase in IOP associated with induction with succinylcholine?

A
  • small dose of a nondepolarizing neuromuscular blocking drug
  • lidocaine
  • β-blocker
  • acetazolamide
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19
Q

How does systemic absorption of topical ophthalmic drugs occur?

A

from the conjunctiva
or
drainage thru nasolacrimal duct onto nasal mucosa

can produce untoward side effects!

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20
Q

a miosis-inducing anticholinesterase that profoundly interferes with metabolism of succinylcholine, causing prolonged paralysis

A

Phospholine iodide (echothiophate)

Atrophine (antiACh) = dilates

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21
Q

Agents that can cause Systemic absorption

A
  • acetylcholine
  • anticholinesterases
  • cyclopentolate
  • epinephrine
  • phenylephrine
  • timolol
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22
Q

Acetylcholine
-effect on eye
-moA
-systemic effect

A

Miosis
Cholinergic agonist
Bronchospasm, bradycardia, hypotension

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23
Q

Oculocardiac Reflex
(OCR)

A

sudden profound decrease in heart rate in response to traction on the extraocular muscles or external pressure on the globe

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24
Q

OCR
what would we see on out monitor?

A

trigeminal nerve afferent limb generates vagal response

  • junctional or sinus bradycardia
  • AV block
  • ventricular bigeminy
  • multifocal PCs
  • VTACH
  • asystole
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25
Q

The OCR is most often encountered during ___ surgery but can occur during any type of ophthalmic surgery

A

strabismus

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26
Q

OCR may also occur while performing an ________ nerve block

A

ophthalmic regional anesthetic

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27
Q

Increases incidence and severity of OCR

A

Hypercarbia, hypoxemia, and light anesthesia

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28
Q

How to treat OCR

A
  • STOP the stimulus (usually quickly fixes)
  • first sign of dysrhythmia: surgery must stop; stop all pressure on the eye or traction on muscles
  • may stop itself after a few minutes
  • give parasympatholytic drug (atropine or glycopyrrolate)
  • anesthetic eye block (abolishing the afferent arc)

(Paradoxically, initial placement of a regional block can induce the OCR)

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29
Q

One of the most important preoperative assessments is…

A

the likelihood of patient movement during surgery

no eye injuries plz

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30
Q

Goals for Anesthesia Management of Ophthalmic Surgery

A
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31
Q

T/F
Site of surgery errors is more common for eye procedures than all other surgeries.

A

True
(except dental and digital)

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32
Q
A
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32
Q

Anesthetic options for most ophthalmic procedures

A
  • general anesthesia
  • retrobulbar (intraconal) block
  • peribulbar (extraconal) anesthesia
  • sub-Tenon block
  • topical analgesia
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33
Q

The anatomic foundation of needle-based eye blocks rests upon the concept of the _____

A

orbital cone

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34
Q

A retrobulbar block is performed by

A

inserting a steeply angled needle from the inferotemporal orbital rim into this muscle cone such that the tip of the needle is behind (retro) the globe (bulbar)

35
Q

Also known as a intraconal block

A

retrobulbar block

36
Q

Which is the intraconal (retrobulbar) block?
Which is the extraconal (peribulbar)?

A

(A): intraconal (retrobulbar); deeper, steeper angle
(B): extraconal (peribulbar); shallower, minimal angle

37
Q

The boundary separating the intraconal from extraconal space is porous, and thus…

A

local anesthetics injected outside the muscle cone diffuse inward

38
Q

A peribulbar block can be achieved by…

A

directing a minimally angled needle to a shallow depth such that the tip remains outside the cone

39
Q

intraconal (retrobulbar)
vs
extraconal (peribulbar)

Which is safer?

A

extraconal block

  • needle is not directed toward the apex of the orbit & farther from key intraorbital structures.
  • minimizes optic nerve trauma, optic nerve sheath injection, orbital epidural, and brainstem anesthesia
40
Q

Complications of Regional Anesthesia for Ophthalmic Surgery

A
41
Q

SATA
Extraconal block local anesthetics are:
A) injected farther from the nerves
B) injected closer to the nerves
C) require larger volumes
D) require more time for diffusion
E) require smaller volumes

A

A) injected farther from the nerves
C) require larger volumes
D) require more time for diffusion

42
Q

Patients must be continuously monitored after anesthetic eye blocks for signs of

A
  • oversedation
  • brainstem anesthesia
  • intravascular absorption
43
Q

requires a separate facial nerve injection to limit blepharospasm

A

intraconal/retrobulbar block

44
Q

The facial nerve
-what does it innervate?
-what blocks it?

A
  • its brancehes innervate the eyelid’s orbicularis oculi muscle
  • blocked by the larger volume of local anesthetic used with extraconal injection
45
Q

Cannula-Based Ophthalmic Regional Anesthesia

A
  • Ophthalmic anesthesia via local anesthetics through a cannula into the space between the globe’s rigid sclera and sub-Tenon capsule
  • cannula into the episcleral (or sub-Tenon) space through a dissection
46
Q

Local anesthetics injected into the sub-Tenon space will…

A

block ciliary nerves that penetrate the capsule and the optic nerve posteriorly

47
Q

Topical Ophthalmic Regional Anesthesia

A

lidocaine gel (barrier to antiseptic)
so
5% betadine drops before applying gel

  • drops minimize astringency of betadine
  • Intraoperatively: surgeon can inject preservative-free LA into the anterior chamber to supplement anesthesia.
48
Q

provides fine detailed vision

A

macula

49
Q

Sudden death during retina surgery

A

venous air embolism introduced into the choroid blood flow during the air/fluid exchange portion of vitrectomy

50
Q

Retina surgery
anesthesia plan

A

(usually long; more eye manipulation)
A) general
B) dense regional block + MAC

51
Q

Nitrous oxide in Retina Surgery

A
  • can expand the gas bubble, increase IOP, cause retinal ischemia & permanent vision loss
  • discontinue 20 minutes before gas injection or omit altogether
52
Q

Glaucoma is commonly characterized as

A

sustained increase in IOP that leads to diminished perfusion of the optic nerve and eventual loss of vision

53
Q

Angle-closure (acute) glaucoma
vs
Open-angle (chronic) glaucoma

A

closed: angle between the iris and cornea narrows and obstructs outflow

open: sclerosis of the trabecular meshwork and impaired aqueous drainage.

54
Q

T/F
Outflow can be improved with constriction of the pupil by using miotic drugs in angle-closure (acute) glaucoma.

A

False
Open-angle (chronic) glaucoma

Miotics treat:
* Open-angle glaucoma by improving the outflow of aqueous humor from the anterior chamber of the eye.
* Angle-closure glaucoma by withdrawing congestion of iris tissue from the angle structures

55
Q

T/F
In glaucoma, IV and eye drop atropine are contraindicated

A

False
IV atropine is minimally absorbed by the eye and should be used when indicated during anesthesia

topical atropine appears to be more of an issue in closed angle glaucome but our book seems to say no atropine drops ever
“Angle-closure (acute) glaucoma occurs ….. Open-angle (chronic) glaucoma results from …. Outflow is improved with constriction of the pupil by miotic drugs. Administration of atropine drops into the eye produce mydriasis and are contraindicated. Intravenous atropine, on the other hand, is minimally absorbed by the eye and should be used when indicated during anesthesia”

56
Q

Strabismus surgery is performed to…

A

correct misalignment of extraocular muscles and realign the visual axis.

57
Q

Strabismus Surgery
Special considerations

A

(1) frequent incidence of intraoperative OCR
(2) potential increased risk for MH
(3) marked prevalence of PONV

58
Q

PONV after ___ surgery varies widely but has been quoted as high as 85%

A

strabismus

59
Q

most common reason for pediatric inpatient admission after outpatient surgery

A

PONV

60
Q

PONV strabismus surgery
MoA

A

vagal-mediated response to surgical manipulation of extraocular muscles

61
Q

Why does Strabismus surgery have a higher incidence of MH?

A

Strabismus is a neuromuscular disorder that can be associated with other myopathies

62
Q

Things we do that increase IOP

A
  • tightly applied facemask
  • laryngoscopy
  • intubation
  • succinylcholine
63
Q

Best position for eye surgery if concerned for aspiration

A

slight reverse Trendelenburg

64
Q

Postoperative Eye Issues

A
  • corneal abrasion
  • acute glaucoma
  • postop vision loss
65
Q

The most common cause of postoperative eye pain after general anesthesia

A

corneal abrasion

66
Q

Corneal Abrasion
-S/S
-causes
-prevention

A
  • conjunctivitis, tearing, and foreign body sensation. dangling ID tags,
  • mask, drapes, losing blink reflex, diminished tear production
  • tape the lids, Protective goggles
  • Ointments: possible allergy; blurred postop vision
67
Q

Corneal abrasion treatment

A
  • Antibiotic ointment and patching the eye
  • usually heals within two days
68
Q

T/F
A miotic pupil may be diagnostic of acute glaucoma.

A

False
mydriatic pupil

69
Q

Postop Acute Glaucoma
treatment

A
  • urgent
  • consult ophthalmologist
  • IV mannitol or acetazolamide can decrease IOP and relieve pain
70
Q

Causes of Postop Painless loss of vision

A

ischemic optic neuropathy (ION)
or
brain injury

71
Q

Causes of Postop Painless loss of vision
increased risk w/…

A

spine surgery in the prone position and cardiac surgery

72
Q

Consultation with an ophthalmologist is mandatory, as early funduscopic examination may aid in diagnosis

A

Postop Painless loss of vision

73
Q

field avoidance

A

airway is fairly inaccessible

(ie: ENT surgery)

74
Q

T/F
Movement can result in endobronchial intubation.

A

True

75
Q

posterior pharyngeal packs

A
  • can minimize the risk of aspiration
  • REMOVE before extubation
76
Q

Intratracheal procedures
airway considerations

A
  • significant edema and acute obstruction
  • postop: some remain intubated; humidified oxygen, nebulized bronchodilators
77
Q

The laryngeal reflex producing laryngospasm is mediated by…

A

vagal stimulation of the superior laryngeal nerve

78
Q

Laryngospasm

A
  • larygenal reflex
  • Abrupt intense, prolonged closure of the larynx compromising gas exchange
  • may occur secondary to instrumentation of the endolarynx, presence of blood or foreign body, and inadequate depth of anesthesia
79
Q

What will happen after your pt laryngospasms?

A

hypercarbia, hypoxia & acidosis triggers ANS response
⬇️
hypertension and tachycardia

80
Q

In small children even brief laryngospasm is perilous because…

A

hypoxemia develops rapidly
d/t reduced FRC & high cardiac output

81
Q

Laryngospasm treatment

A
  • 100% O2 via positive-pressure facemask ventilation
  • OPA
  • deepen anesthesia
  • Small dose succinylcholine (0.25-0.5 mg/kg) and tracheal intubation may be necessary in refractory cases
82
Q

Using this may reduce laryngospasm

A

IV or topical lidocaine spray
before laryngoscopy and endotracheal intubation

83
Q

Your pt scheuled for ENT surgery has an Upper Respiratory Infection. How does this affect anesthesia?

A
  • airway hyperreactivity
  • Esp children; ↑risk of intraop breath-holding, hypoxemia, postop croup
  • Postponing is controversial; may not be required for brief nonairway ENT procedures (myringotomy and tube placement)
84
Q

massive epistaxis
presentation

A

anxious, hypovolemic, and hypertensive

85
Q

Epistaxis
anesthesia implications

A
  • Rehydrate (large-bore IV)
  • reassure
  • high risk regurgitation & aspiration of gastric contents because large amounts of blood are swallowed
  • blood loss is occult
86
Q

T/F
The optic nerve contains CSF.

A

True

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