M&M Ch 36 Part 1

Question 1

Any factor that increases intraocular pressure in the setting of an open globe may cause

Answer 1

drainage of aqueous or extrusion of vitreous through the wound, serious complications that can permanently damage vision.

Question 2

Succinylcholine increases intraocular pressure by ____________ for ____________ min after administration

Answer 2

5-10 mmHg

for 5 to 10 min

Question 3

is succinylcholine contraindicated in cases of open eye injuries

Answer 3

NO

in studies of hundreds of patients with open eye injuries, no patient experienced extrusion of ocular contents after administration of succinylcholine.

Question 4

Traction on extraocular muscles, pressure on the eyeball, administration of a retrobulbar block, and trauma to the eye can elicit

Answer 4

a wide variety of cardiac arrhythmias ranging from bradycardia and ventricular ectopy to sinus arrest or ventricular fibrillation.

Question 5

Complications involving the intraocular expansion of gas bubbles injected by the ophthalmologist can be avoided by

Answer 5

• stop nitrous at least 15 min prior to air injection or sulfur hexafluoride
• or avoid nitrous oxide entirely.

Question 6

Medications applied topically to mucosa are absorbed

Answer 6

systemically at a rate intermediate between absorption following intravenous and subcutaneous injection.

Question 7

an irreversible cholinesterase inhibitor now rarely used in the treatment of glaucoma

Answer 7

echothiophate

Question 8

topical application of echothiophate

Answer 8

leads to systemic absorption and inhibition of plasma cholinesterase activity. Because succinylcholine is metabolized by this enzyme, echothiophate will prolong its duration of action.

Question 9

The key to inducing anesthesia in a patient with an open eye injury is

Answer 9

controlling intraocular pressure with a smooth induction.

Question 10

Coughing and gagging during intubation are avoided by

Answer 10

first achieving a deep level of anesthesia and profound paralysis

Question 11

The postretrobulbar block apnea syndrome is probably due to

Answer 11

the injection of local anesthetic into the optic nerve sheath, with spread into the cerebrospinal fluid.

Question 12

normal intraocular pressure

Answer 12

12-20 mm Hg

Question 13

glaucoma is caused by

Answer 13

obstruction to aqueous humor outflow

Question 14

intraocular pressure will ____________ if the volume of blood within the globe is increased

Answer 14

rise

Question 15

what events can adversely affect intraocular pressure

Answer 15

any event that alters arterial or central venous blood pressure or ventilation (eg, laryngoscopy, intubation, airway obstruction, coughing, Trendelenburg position)

Question 16

what happens to intraocular pressure when PaCO2 ↑

Answer 16

intraocular pressure ↑

Question 17

what happens to intraocular pressure when PaO2 ↓

Answer 17

intraocular pressure ↑

Question 18

____________ helps maintain the shape and the optical properties of the eye

Answer 18

intraocular pressure

Question 19

Pressure on the eye from ____________ (3) can lead to a marked increase in intraocular pressure, possible eye pain, and temporary or permanent visual changes.

Answer 19

a malpositioned mask, improper prone positioning, or retrobulbar hemorrhage

Question 20

blinking raises intraocular pressure by

Answer 20

5 mmHg

Question 21

squinging may transiently increase intraocular pressure …

Answer 21

greater than 50 mm Hg

Question 22

even brief episodes of increased intraocular pressure in patients with underlying low ophthalmic artery pressure may cause

Answer 22

retinal ischemia

Question 23

When the globe is opened by surgical incision or traumatic perforation, intraocular pressure

Answer 23

approaches atmospheric pressure.

Question 24

Any factor that increases intraocular pressure in the setting of an open globe may cause

Answer 24

drainage of aqueous or extrusion of vitreous through the wound (serious complications that can permanently damage vision)

Question 25

open-eye surgical procedures

Answer 25

Question 26

how do most anesthetic drugs affect intraocular pressure

Answer 26

Most anesthetic drugs either reduce intraocular pressure or have no effect

Question 27

Intraocular pressure ____________ with inhalational anesthetics in proportion to anesthetic depth.

Answer 27

decreases

Question 28

why do inhalational agents decrease intraocular pressure

Answer 28

Decreased blood pressure reduces choroidal volume, relaxation of the extraocular muscles lowers wall tension, and pupillary constriction facilitates aqueous outflow.

Question 29

which IV anesthetic does not reduce intraocular pressure

Answer 29

ketamine

usually ↑

Question 30

inhaled anesthetics, IV anesthetics, and muscle relaxant effects on intraocular pressure

Answer 30

Question 31

Topically administered anticholinergic drugs result in ____________ which may cause ____________

Answer 31

pupillary dilation (mydriasis), which may precipitate or worsen angle-closure glaucoma

Question 32

T/F Systemically administered atropine or glycopyrrolate is not associated with intraocular hypertension, even in patients with glaucoma.

Answer 32

TRUE

Question 33

what muscle of the eye contracts causing ↑ intraocular pressure

Answer 33

extraocular muscles

Question 34

do non-depolarizing NMBAs increase intraocular pressure

Answer 34

no

Question 35

oculocardiac reflex consists of

Answer 35

a trigeminal (V1) afferent and a vagal efferent pathway

Question 36

when is the oculocardiac reflex mostly seen

Answer 36

most commonly encountered in children undergoing strabismus surgery

Question 37

in awake patients, the oculocardiac reflex may be accompanied by…

Answer 37

nausea

Question 38

t/f prophylaxis for the oculocardiac reflex is always taken

Answer 38

FALSE
Routine prophylaxis for the oculocardiac reflex is controversial, especially in adults

Question 39

what med can prevent the oculocardiac reflex

Answer 39

anticholinergic medication

Question 40

____________ is more effective for preventing the oculocardiac reflex than intramuscular premedication

Answer 40

IV atropine or glycopyrrolate

Question 41

____________ should be administered with caution to any patient who has or may have CAD

Answer 41

anticholinergic medication

bc of an increase in HR that can cause myocardial ischemia

Question 42

____________ may also preempt the oculocardiac reflex

Answer 42

retrobulbar blockade or deep inhalational anesthesia

Question 43

management of the oculocardiac reflex

Answer 43

(1) immediate notification of the surgeon and cessation of surgical stimulation until heart rate recovers

(2) confirmation of adequate ventilation, oxygenation, and depth of anesthesia

(3) administration of intravenous atropine (10 mcg/kg) if bradycardia persists

(4) in recalcitrant episodes, infiltration of the rectus muscles with local anesthetic

Question 44

Intravitreal air injection will tend to …

Answer 44

flatten a detached retina and facilitate anatomically correct healing.

Question 45

when is Nitrous Oxide administration contraindicated

Answer 45

intravitreal air injection

Question 46

why is Nitrous Oxide contraindicated in intravitreal air injection

Answer 46

Nitrous oxide is 35 times more soluble than nitrogen in blood

Thus, it tends to diffuse into an air bubble more rapidly than nitrogen (the major component of air) is absorbed by the bloodstream.

If the bubble expands after the globe is closed, intraocular pressure will rise.

Question 47

sulfur hexafluoride is (more/less) soluble than nitrous oxide

Answer 47

much less soluble than Nitrous Oxide

Question 48

Unless high volumes of pure sulfur hexafluoride are injected…

Answer 48

the slow bubble expansion does not typically increase intraocular pressure.

Question 49

fall in intraocular pressure could precipitate

Answer 49

retinal detachment