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BARASH | Chapter Digest > CHAPTER 49 | ANESTHESIA FOR Ophthalmic Surgery > Flashcards

CHAPTER 49 | ANESTHESIA FOR Ophthalmic Surgery Flashcards

1
Q

The afferent limb of the oculocardiac reflex:

A. CN 7

B. CN 10

C. CN 5

A

A. CN 7 (trigeminal nerve)

The oculocardiac reflex is triggered by pressure on the globe and by traction on the extraocular muscles as well as on the conjunctiva or on the orbital structures.

This reflex, whose afferent limb is trigeminal and efferent limb is vagal, may also be elicited by performing a regional eye block, by ocular trauma, and by direct pressure on tissue remaining in the orbital apex after enucleation.

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2
Q

The innermost layer of the eye:

A. Retina

B. Cornea

C. Uveal tract

A

A. Retina

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3
Q

What is the average rate of aqueous humor production?

A. 500 uL/min

B. 2uL/min

C. 4uL/min

A

B. 2uL/min

The average rate of aqueous humor production of 2 μL/min.

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4
Q

IOP (intraocular pressure) is considered abnormal if above:

A. 22 mmHg

B. 24 mmHg

C. 18 mmHg

A

A. 22 mmHg

IOP normally varies between 10 and 21.7 mmHg and is considered abnormal above 22 mmHg. This level varies from 1 to 2 mmHg with each cardiac
contraction.

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5
Q

Which of the following increases IOP?

A. Etomidate

B. Hyperventilation

C. CO2

D. Mannitol

A

C. CO2

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6
Q

TRUE or FALSE

During anesthesia, a rise in IOP can temporarily result to a visual loss.

A

FALSE

During anesthesia, a rise in IOP can produce permanent visual loss.

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7
Q

Which of the following is avoided in patients with closed-angle glaucoma?

A. Scopolamine

B. Atropine

C. Glycopyrrolate

A

A. Scopolamine

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8
Q

TRUE or FALSE

Any maneuver that increases venous pressure in the eye can elevate the IOP

A

TRUE

Because a rise in venous pressure produces an increased volume of ocular blood and decreased aqueous outflow, it is obvious that considerable elevation of IOP occurs with any maneuver that increases venous pressure.

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9
Q

Which of the following situation does NOT cause an elevation of the IOP?

A. Overhydration

B. Prone position

C. Hypercapnia

D. Trendelenburg

E. Giving a bolus of Mannitol

A

E. Giving a bolus of Mannitol

Maneuvers that can elevate the IOP:

Overhydration, constriction around the patient’s neck, prolonged Trendelenburg or prone
position, and hypercapnia, hypercapnia, which may induce choroidal vascular congestion!

CHOROIDAL VENOUS CONGESTION > Increased IOP!

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10
Q

The onset of primary congenital glaucoma is:

A. 0 - 3 y.o.

B. anytime after birth until 1 year old

C. 0 - 5 y.o.

A

A. 0 - 3 y.o.

Primary congenital glaucoma is classified according to age of onset, with the infantile type presenting any time after birth until 3 years of age.

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11
Q

Which drug is useful during examination of infantile glaucoma under general anesthesia?

A. Succinylcholine

B. Ketamine

C. Mannitol

D. Atropine

A

B. Ketamine

Some clinicians maintain that ketamine is a
useful drug to use for examination under anesthesia when infantile glaucoma
is part of the differential diagnosis because ketamine does not appear to spuriously lower IOP measurement, moreover, even normal infants sporadically have pressures in the mid-20s

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12
Q

Which of the following decreases IOP?

A. Overhydration

B. Hyperthermia

C. Hyperventilation

D. Hypoventilation

A

C. Hyperventilation

Hyperventilation decreases IOP, whereas asphyxia, administration of carbon dioxide, and hypoventilation have been shown to elevate IOP.

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13
Q

Which of these drugs DOES not reduce the IOP?

A. Dexmedetomidine

B. Etomidate

C. Barbiturates

D. Dextran

E. Ketamine

A

E. Ketamine

virtually all CNS depressants, including
propofol and etomidate, dexmedetomidine, barbiturates, neuroleptics, opioids, and hypnotics, lower IOP at dose ranges for sedation and general
anesthesia in both normal and glaucomatous eyes

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14
Q

TRUE or FALSE

All nondepolarizing neuromuscular agents given in equipotent ED95 doses directly lower IOP by
relaxing the extraocular muscles.

A

TRUE

In contrast, depolarizing agents such as succinylcholine lead to an increase in IOP.

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15
Q

What are the mechanisms involved why IOP is elevated after giving succinylcholine?

A

An average peak IOP increase of about 9 mmHg is produced within 1 to 4 minutes of an intubating dose of succinylcholine which returns to baseline
typically within 7 minutes.

The ocular hypertensive effect of succinylcholine has been attributed to several mechanisms, including the tonic contraction of extraocular muscle fasciculation,6 choroidal vascular dilation, and relaxation of orbital smooth muscle.

IOP elevation and sux: 9 mmHg

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16
Q

Which of the following is MOST accurate regarding OCR (Oculocardiac Reflex)?

A. Atropine given intravenously within 5 -10 minutes of surgery may reduce the incidence of the reflex

B. The afferent limb is facial and the efferent limb is vagal

C. common manifestation of the oculocardiac reflex is sinus premature ventricular contraction

D. This reflex is uniquely occurring during general anesthesia only

E. With repeated manipulation, bradycardia is least like to be repeated

A

E. With repeated manipulation, bradycardia is least like to be repeated

  • Choice A is wrong because it should be 30 mins prior.
  • The afferent limb is TRIGEMINAL
    The efferent limb is VAGUS
  • The most common symptom is SINUS BRADYCARDIA
  • This can happen in local or general anesthesia.
17
Q

Refractory TCR (Trigimino-cardiac reflex) can be treated with epinephrine. What is the ideal dose:

A. 0.1mcg/kg

B. 0.5 - 1mcg/kg

C. 1mg

A

B. 0.5 - 1mcg/kg

Profound or refractory TCR is treated by ceasing catheter advancement, 100% oxygen, employing
higher airway pressures, and administration of IV boluses of 0.5 to 1.0 mcg/kg epinephrine

18
Q

This long-acting anticholinesterase miotic drug lowers IOP by decreasing resistance to the
outflow of aqueous humor:

A. Mannitol

B. Acetazolamide

C. Phospholine iodide

A

C. Phospholine iodide

19
Q

This anticholinesterase drug may prolong the action of succinylcholine by reducing plasma
pseudocholinesterase activity:

A. Echothiophate

B. Neostigmine

C. Galantamine

D. Pyridostigmine

A

A. Echothiophate

It may prolong the action of succinylcholine by reducing plasma pseudocholinesterase activity by 95% following absorbtion into the systemic
circulation after conjunctival instillation. Moreover, normal enzyme activity does not return until 4 to 6 weeks after discontinuation of the drug.

20
Q

maximal dose of cocaine in ophthalmic surgery is:

A. 3mg/kg

B. 150 mg

C. 1.5mg/kg

A

A. 3mg/kg

21
Q

Which drug decreases the IOP by dehydrating the vitreous?

A. Mannitol
B. Acetazolamide
C. Timolol

A

A. Mannitol

glycerol and mannitol, decreases IOP by dehydrating the vitreous while acetazolamide decreases aqueous production.

22
Q

recommended IV dose of mannitol for eye surgery is up to:

A. 1g/kg

B. 10mg/kg

C. 15 mg/kg

A

A. 1g/kg

23
Q

Patients with coronary stents can have a safe cataract surgery __ after stent placement.

A. 30 days

B. 2 weeks

C. 7 days

D. 3 months

A

A. 30 days

The Society for Ambulatory Anesthesia recommends that patients with coronary stents
can have cataract surgery 30 days after stent placement, provided that antiplatelet therapy has been uninterrupted.

24
Q

What is the recommended dose of dexmedetomidine that can be administered 15 minutes to decrease bucking or coughing prior to emergence from general anesthesia?

A. 0.25 to 1.0 mcg/kg

B. 1.0 - 2.0 mcg/kg

C. 0.1 to 0.15 mcg/kg

A

A 0.25 to 1.0 mcg/kg dose of dexmedetomidine
administered 15 minutes prior to emergence from general anesthesia decreases coughing and agitation in a dose-dependent fashion

25
Q

This drug is to be avoided if forced duction
testing (FDT) is to be performed during
strabismus surgery:

A. Propofol
B. Halothane
C. Succinylcholine
D. Fentanyl

A

C. Succinylcholine

26
Q

True of oculocardiac reflex EXCEPT:

A. The most common manifestation of the oculocardiac reflex is sinus bradycardia

B. The efferent limb is vagal

C. Inclusion of atropine in the usual premedication regimen for prophylaxis
is ineffective

D. With repeated manipulation, bradycardia is more likely to recur

A

D. With repeated manipulation, bradycardia is more likely to recur

BARASH | Chapter Digest (24 decks)

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