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Anesthesia Concepts 4 (Butera) > Ophthalmic Anesthesia > Flashcards

Ophthalmic Anesthesia Flashcards

1
Q

Optic Neve photo

A
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2
Q

The ophthalmic artery is ______.

A

the main blood supply to the eye. It branches from the internal carotid artery near the Circle of Willis

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3
Q

The ophthalmic artery divides into the ______.

A

central retinal artery and the posterior ciliary arteries
The superior and inferior ophthalmic veins transport venous blood to the cavernous sinus

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4
Q

photo of the vascular supply to the eye

A
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5
Q

Function of the lacrimal gland

A
  • produces the aqueous layer of the eye’s tear film
  • aqueous layer of tears is made up of water, proteins, vitamins, electrolytes, and other substances
  • these substances help lubricate the eye, wash away debris, and promote overall eye health
  • tears get to the eye through the puncta
  • can trigger reflex tears when something gets in your eye
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6
Q

Miosis = ____
What medications cause miosis?

A

constriction of the pupil

acetylcholine

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7
Q

Glaucoma = ____

What meds treat it?

A

increased intraocular pressure

Acetazolamide, Echothiophate ,Timolol

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8
Q

Mydriasis = ______

What causes it?

A

Pupillary dilation, ophthalmic capillary decongestion

Atropine, Cyclopentolate, Epinephrine, Phenylephrine, Scopolamine

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9
Q

Phenylephrine drops: clinical use? Systemic effects?

A

causes MYDRIASIS

systemic effects: SEVERE HTN, ARRYTHMIAS, HEADACHES, TREMORS, MYOCARDIAL ISCHEMIA

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10
Q

Epinephrine drops: clinical use? Systemic effects?

A

used for: REDUCES IOP

systemic effects: TACHYARRHYTHMIAS , PVC

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11
Q

Timilol drops: clinical use? Systemic effects?

A

used for: REDUCES IOP & TREATS GLAUCOMA

systemic effects: BRADYCARDIA, HYPOTENSION, CHF, EXACERBATION OF ASTHMA AND MYASTHENIA GRAVIS

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12
Q

Echthiophate drops: clinical use? Systemic effects?

A

used for: TREATS GLAUCOMA & MIOSIS

systemic effects: PROLONGED RESPONSE TO SUCCINYLCHOLINE AND ESTER LINKED LOCAL ANESTHETICS

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13
Q

Acetylcholine drops: clinical use? Systemic effects?

A

causes miosis

systemic effects: BRADYCARDIA, HYPOTENSION, BRONCHOSPASM, INCREASES SECRETIONS

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14
Q

CYCLOPENTOLATE drops: clinical use? Systemic effects?

A

causes MYDRIASIS. Used to dilate pupil.

systemic effects: DISORIENTATION, DYSARTHRIA, SEIZURES

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15
Q

SCOPOLAMINE drops: clinical use? Systemic effects?

A

causes MYDRIASIS. Used to dilate the pupil.

systemic effects: DISORIENTATION AND HALLUCINATIONS

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16
Q

COCAINE drops: clinical use? Systemic effects?

A

causes VASOCONSTRICTION

systemic effects: SEVERE BRADYCARDIA

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17
Q

Class of acetylcholine

A

cholinergic agonist

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18
Q

Class of acetazolamide
Systemic effect?

A

Carbonic anhydrase inhibitor
Systemic effect: Diuresis, hypokalemic metabolic acidosis

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19
Q

Class of Echothiophate
Systemic effects?

A

Irreversible cholinesterase inhibitor

Prolongation of succinylcholine’s effects
Reduction in plasma cholinesterase activity up to 3-7 weeks after discontinuation
Can cause Bradycardia, bronchospasm

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20
Q

Class of Timilol
Systemic effects?

A

b-Adrenergic antagonist

Atropine-resistant bradycardia, bronchospasm, exacerbation of congestive heart failure; possible exacerbation of myasthenia gravis

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21
Q

Atropine is a ____
It could cause ____

A

Anticholinergic

Central anticholinergic syndrome; delirium, agitation, fever, flushing, xerostomia, and anhidrosis
Blurred vision (cycloplegia, photophobia)

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22
Q

Cyclopentolate is a ____
It could cause _____

A

Anticholinergic
Disorientation, psychosis, convulsions, dysarthria

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23
Q

Epinephrine is a ____
Is could cause ____

A

a-, b-Adrenergic agonist
Hypertension, tachycardia, cardiac dysrhythmias; epinephrine paradoxically leads to decreased intraocular pressure and can also be used for glaucoma

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24
Q

Phenylephrine is a ___
It could cause _____

A

a-Adrenergic agonist, direct acting vasopressor

Hypertension (one drop, or 0.05 mL, of a 10% solution contains 5 mg of phenylephrine)

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25
Q

Scopolamine is a ____
It could cause _____

A

Anticholinergic
Central anticholinergic syndrome (see atropine above)

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26
Q

Goals of an eye block/meds to use

A

Reduce pain, amnesia, limit patient movement, with minimal respiratory and cardiovascular side effects

Propofol
Remifentanil
Midazolam
Fentanyl

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27
Q

Retrobulbar Block

A

A needle steeply inserted from the orbital rim into the muscle cone behind the globe, sm. volume of local anes.

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28
Q

Peribulbar Block

A

A needle minimally angled shallow and outside the muscle cone, safer larger volume of local anes. are needed and slower onset

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29
Q

Sub Tenon Block

A

Local anes. Injected into the sub- Tenon space

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30
Q

photo of Sub Tenon block

A
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31
Q

Complications of eye blocks

A

Oculocardiac Reflex (OCR)
Hemorrhage
Brainstem Anesthesia
Globe perforation
Myotoxicity
Optic nerve damage
Seizures

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32
Q

Trigeminovagal or OCR

A

Pressure on the globe or traction on the extraocular muscles can result in bradycardia, atrioventricular block, or asystole.

OCR occurs most often during strabismus surgery in children

Hypercarbia, hypoxemia and light anesthesia augment the incidence and severity

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33
Q

Treatment of Trigeminovagal or OCR

A

The first step in treating OCR is to stop the stimulation by the surgeon. Repeated and sustained stimulation cause OCR to fatigue.

Atropine 10mcg/kg IV
If GA ensure adequate depth
Maintain normal PaCO2

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34
Q

Retrobulbar Hemorrhage = ____

treatment?

A

Usually noted during injection, eye tenses and pushes forward

Complication is less likely with peribulbar or sub-tenon blocks

Treatment 1. gentle pressure 2. Lateral canthotomy may be necessary to relieve pressure on the optic nerve 3. reschedule surgery

35
Q

Brainstem anesthesia

A

Clinical picture includes:
Amaurosis
Gaze Palsy
Dysphagia
Cardiac arrest
Shivering
Apnea
Tachycardia hypertension
Loss of consciousness
Dilatation of the contralateral pupil

36
Q

Other serious complications that occur with anesthesia to the eye

A

Myotoxicity of local anesthesia resulting in diplopia

Direct trauma to the eye

Seizures

37
Q

Normal Intraocular pressure = ____

A

10-22 mmHg

38
Q

Diurnal Variation & Positional Changes = ___

A

1-6 mmHg

39
Q

Formula for Intraocular perfusion pressure =

A

MAP-IOP

40
Q

Major determinants of IOP

A

Aqueous humor dynamics

Changes in the choroid blood volume(CBV)

Central Venous pressure

Extraocular muscle tone

Valsalva Maneuver

41
Q

Aqueous Humor Dynamics

A

Major physiologic determinant of IOP
Balance between production and elimination

Produced by the ciliary process (Posterior Chamber) filtered by the trabecular meshwork and reabsorbed by the Canal of Schlemn (Anterior Chamber) exits the eye into episcleral veins.

42
Q

Factors that influence IOP

A
  • Venous congestion, A direct relationship exists between CVP and IOP
  • Coughing straining or vomiting can increase IOP 40 mmHg
  • Laryngoscopy and intubation
  • Sudden increases or decreases in blood pressure will increase or decrease IOP transiently
  • External compression of the globe
  • Hypoxemia and hypoventilation increase
  • Hyperventilation and hypothermia decrease
43
Q

CNS depressants generally do what to IOP?

A

CNS DEPRESSANTS GENERALLY LOWER IOP
These centers are depressed by sedatives, narcotics, barbiturates, and volatile anesthetics

44
Q

What can increase IOP?

A
  • Succinylcholine increases IOP, Ketamine may increase IOP
  • Laryngoscopy and endotracheal intubation will increase IOP
45
Q

Acetazolamide and its effect on the aqueous humor

A

Reversibleinhibitor of the carbonic anhydrase

Decreases formation of aqueous humor through decreased carbonic anhydrase activity
results in reduction of hydrogen ion secretion at the renal tubule and an increased renal excretion of sodium, potassium, bicarbonate, and water.

46
Q

How does Mannitol work in the eye?

A

Mannitol reduces IOP bydehydrating the vitreous along an osmotic gradient.

Mannitoldehydrates the vitreous humor by drawing water out of the vitreous humor and into the blood vessels.
The vitreous humor has less water, after being dehydrated by the mannitol, it has less mass and thus creates less pressure.

47
Q

When CVP is increased, what happens to IOP?

A

marked increase

48
Q

When CVP is decreased, what happens to IOP?

A

marked decrease

49
Q

When arterial BP is increased, what happens to IOP?

A

mild increase

50
Q

When arterial BP is decreased, what happens to IOP?

A

mild decrease

51
Q

When paCO2 is increased (hypoventilation), what happens to IOP?

A

moderate increase

52
Q

When paCO2 is decreased (hyperventilation), what happens to IOP?

A

moderate decrease

53
Q

When paO2 is increased, what happens to IOP?

A

no effect

54
Q

When paO2 is decreased, what happens to IOP?

A

mild increase

55
Q

effect of volatile agents on IOP

A

moderate decrease

56
Q

effect of nitrous oxide agents on IOP

A

mild decrease

57
Q

effect of barbiturates on IOP

A

moderate decrease

58
Q

effect of benzodiazepines on IOP

A

moderate decrease

59
Q

effect of ketamine on IOP

A

conflicting evidence

60
Q

effect of opioids on IOP

A

mild decrease

61
Q

effect of depolarizing muscle relaxants on IOP

A

moderate increase

62
Q

effect of non-depolarizing muscle relaxants on IOP

A

no change or mild decrease

63
Q

To prevent an increase in IOP, avoid direct pressure on the ____.

A

Globe
Use a plastic shield over the eye
No peribulbar or retrobulbar injections
Careful facemask technique

64
Q

To prevent an increase in IOP, avoid increase in ____

A

CVP
Prevent coughing during induction and intubation
Ensure a deep level of anesthesia and relaxation prior to laryngoscopy
Avoid head down position
Extubate under deep anesthesia

65
Q

AVOID PHARMACOLOGIC AGENTS THAT INCREASE IOP
(PREVENTING ASPIRATION) by using ______

A

Metoclopramide, Histamine H2 receptor antagonists, non-particulate antacids
? Nasogastric tube
RSI Induction/ extubate awake

66
Q

Intravitreal injection of gas for ?cataract surgery
(re-listen to his lecture? this slide is weird)

A

Sulfur hexafluoride (SF6) and Carbon octofluorine (perfluoropropane)(C3F8) are commonly used during retinal detachment surgery.
Nitrous oxide: avoid 7-10 days w/ SF6, 30 days w/ C3F8, 5 days w/ air, 0 days w/ silicone oil

Air travel can cause increase in IOP

67
Q

Strabismus

A

Surgery for poor alignment of the visual axis, which must be treated by 4 months of age for proper stereoscopic visual development

Three problems associated with these patients are MH, PONV, and OCR

68
Q

Measures to decrease PONV

A

Minimal use of opioids
The use of Propofol and +/- volatile anesthetic
Avoid the use of N2O
Administration of serotonin (5HT3) antagonist
Use of dexamethasone
Insertion and removal of orogastric tube
Gentle manipulation of the eye muscles
Maintenance of adequate hydration
Placement of lidocaine near the extraocular muscle during surgery to minimize afferent impulses and post operative pain

69
Q

Measures to decrease PONV

A

Minimal use of opioids
The use of Propofol and +/- volatile anesthetic
Avoid the use of N2O
Administration of serotonin (5HT3) antagonist
Use of dexamethasone
Insertion and removal of orogastric tube
Gentle manipulation of the eye muscles
Maintenance of adequate hydration
Placement of lidocaine near the extraocular muscle during surgery to minimize afferent impulses and post operative pain

70
Q

Perioperative vision loss (POVL)

A

POVL assumed to be related to ischemic optic neuropathy or central retinal artery occlusion
High risk patients are spine surgeries positioned prone for prolonged procedures with substantial blood loss
Surgeons should inform patients
Rare incidence less than 0.2% of spine surgeries

71
Q

Preventing/recognizing post op vision loss

A

Monitoring IOP during steep trendelenberg
Molloy Bridgeport Anesthesia Associates Observation Scale (MBOS)
Eyelid edema is a sign of rise in IOP

OPP=MAP-IOP

72
Q

Chemosis =

A

swelling of the eyelids
Chemosis identifies IOP greater than 40 mmHg and a need to use intervention to lower IOP

73
Q

Perioperative vision loss risk factors

A

Prolonged prone or head down position
Male gender
Obesity
Increased blood loss

74
Q

Corneal abrasion

A

Postoperative eye pain most commonly caused by corneal abrasion

Treatment by topical application of antibiotic and covering with an eye patch for 48hr

Topically applied anesthetic or steroids are contraindicated

75
Q

Most eye surgeries are performed under ___

A

MAC with or without regional blocks

76
Q

Keratoplasty = ___

A

Replacement of cornea with donor tissue

77
Q

Pterygium = ____

A

Benign growth of conjunctiva removed when vision is impaired

78
Q

Trabeculectomy = ___

A

To treat glaucoma

79
Q

Vitrectomy = ___

A

Surgical extraction of vitreous chamber

80
Q

Ectropion Repair = ___

A

Remove excess upper eyelid tissue

81
Q

Entropion Repair = ___

A

Remove excess lower eyelid tissue

82
Q

Blepharoplasty = ___

A

Any plastic surgery of the eyelids

83
Q

Dacryocystorhinostomy = _____

A

Correction of obstructed tear ducts

84
Q

Emergency surgery could necessitate balancing the need for what?

A

rapid sequence induction against prevention of increases in IOP that could cause further eye injury

Discuss the medications needed to blunt the CV response to laryngoscopy and endotracheal intubation before RSI.

Anesthesia Concepts 4 (Butera) (15 decks)

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