Opthamology And Otolaryngology 2

Front 1

What are the 3 branches of the trigeminal nerve?

Back 1

Opthalmic - 3 branches
Maxillary - innervation of upper lip, nasal mucosa and scalp
Mandibular - Innervation of lower jaw

Front 2

What are the 3 branches of the Ophthalmic branch of the Trigeminal nerve?

Back 2

a) Lacrimal branch - Innervation of lacrimal glands

b) Frontal branch - innervation of forehead and medial upper eyelids.

c) Nasociliary: innervation of upper lip, nasal mucosa and scalp

Front 3

What are the topically applied mydriatic agents seen in ophtalmics?

Back 3

Need dilated pupil for visualization.
Topically applied mydriatics:

Phenylephrine: alpha-agonist; systemic absorption assoc w/HTN and dysrhythmias (rare). Effects increased by TCAs, MAOIs, Reserpine, Methyl-dopa.

Mydriacil/tropicamide - synthetic anticholinergic;

Epinephrine - sympathetic agonist (alpha, beta); systemic absorption assoc w/ cardiac dysrhythmias. Often used in lavage solutions, also.

Mydriatics can worsen glaucoma or precipitate acute glaucoma.

Front 4

What are some common Cycloplegics (cause temporary paralysis of ciliary muscles - loss of accomodation and near vision) used in ophthalmic surgery?

Back 4

All are anticholinergics:

Atropine: anticholinergic; systemic absorption associated with central anticholinergic syndrome (agitation, hall, unconsc.) **MINIMAL EFFECTS ON EYE WITH IV INFUSION**

Homatropine: anticholinergic; more rapid onsent and less dramatic dilation vs atropine; 10x less potent than atropine;
LASTS UP TO 24 HOURS.

Cyclopentolate/Cyclogyl: synthetic Anticholinergic; systemic absorption assoc w/disorientation and psychotic rxn.

Front 5

What is Flurbiprophen?

Back 5

Topical NSAID used in eyes to decrease inflammation s/t decreased prostaglandin production.

Front 6

Why are cholinergic agonists used in opth. procedures? What are some?

Back 6

Cholinergic agonists (topical) are used to induce miosis (pupillary constriction) post procedure in opth. procedures.

Pilocarpine

Carbachol

Ach: anticholinergic; systemic effects include bronchospasm, bradycardia and HOTN.

Front 7

Why are systemic diurectics used in ophthalmic pts?

Back 7

To decrease IOP.

Mannitol (IV):
-Peak effect in 1 hour
-Initial HTN so can exacerbate pre-ex HTN; this is followed by HOTN
-Hypovolemia s/t brisk diuresis
-Place a foley - pt may not be able to be still with full bladder.
-Can result in -lyte imbalances
-If pt has renal dysfx, can develop pulm edema and CHF.

Glycerin/Osmoglyn (PO):
- may cause hyperglycemia
-Esp with diabetics, check a BS before they leave

Diamox (ACTZ - Carbonic Anhydrase Inhibitor)
-Decreases prod of aq humor
-IV 500 mg if eye is tight; peak effect in 20'
-Also used for altitude sickness b/c it pulls fluid off brain

Front 8

How does ACTZ(Diamox) decrease IOP?

Back 8

ACTZ is a carbonic anhydrase inhibitor. This results in a decrease in the production of aqueous humor to decrease IOP.
-Acts quickly but is less effective than mannitol.

Front 9

What are some intraocular gases and why are they used?

Back 9

Intraocular gases, like Sulfur Hexafluoride and Perfluoropropane, are inert gases.

These gases are used to form a bubble to displace the retina back into place after it has been detached.

-Avoid use of N2O or d/c N2O 15 minutes before gas bubble is insufflated into eye.

Front 10

Aqueous Humor: how/ where is it formed and how is it eliminated?

Back 10

The vast majority of aqueous humor is formed in the posterior chamber of the ciliary body by carbonic anhydrase processes. The remainder is from fluid leakage from vessels on anterior surface of iris.

A.H. is eliminated va the trabecular network thru the canal of Schlemm.

Front 11

What are some EXTERNAL factors that increase IOP?

Back 11

-Normal blinking (↑IOP by 5-15 mmHg)
-Normal eye motion
-Coughing, sneezing, valsava,, vomiting, similar acute periods of increased venous pressure (↑IOP by 35-50 mmHg)
-Prone position --> venous congestion
-Direct pressure on eye (improper prone positioning changes IOP by changing shape and size w/t changing volume of eye)

-Hypercarbia and Hypoxia

Front 12

Why is the oculocardiac reflex called the "five and dime" reflex?

Back 12

B/C it involves CN V (trigeminal) and CN X (vagus) and can reslult from almost any manipulation of ocular structures.

Most common sx: bradycardia.

Front 13

Why is the oculocardiac reflex such a concern?

Back 13

B/C it is not suppressed by GA so reflex bradycardia can occur at any point in the surgery.

Bradycardia can lead to HOTN which can lead to cardiac arrest.

-Afferent path: Opthalmic division of the Trigeminal nerve (CNV)
-Efferent path: Vagus nerve (CN X)

Stimuli of oculocardiac reflex:
-External pressure on the globe
-#1 cause: Traction on extraocular muscles
-almost any manipulation of ocular structures.

Seen most commonly in children extraocular muscle surgery (strabismus) - MANY ANESTHETISTS ROUTINELY GIVE PROPHYLACTIC ATROPINE TO CHILDREN UNDERGOING STRABISMUS SURGERY B/C INCREASED VAGAL REFLEXES ARE PRESENT IN THIS GROUP.
**Tab says pretx with Robinul right before the stimulus is best, but this is hard to do.

-Awake pt can also experience N/V and increased sleepiness.

-Reflex tends to fatigue and subsequent stim elicits a diminished response.

Tx:
-Stop stimulation is FIRST step!!!
-Atropine if HR does not respond to removal of stimulus. (Tab says give it anyway).
-pretx before stim prn. (ideal, not feasible)
-Surgery not to resume until HR increases


***Elderly pt drops BP fast b/c they have less compliant ventricle & fixed SV so they are RATE DEPENDENT for their BP.***

Front 14

How can the anesthetist assess the adequacy of ocular regional anesthesia?

Back 14

Ocular regional anesthesia is adequate if the patient cannot move their eye.

Front 15

When is an awake procedure not appropriate during ocular surgery?

Back 15

Mentally Impaired pt.
Anxious patient (unwilling or unable to lie still)
Young children
Occassionally the elderly
Claustrophobics (due to heavy draping)
Heat intolerant (heavy draping)
Pt. with generalized aches and pains (narcotics may help, but itching from histamine release or N/V - which can be disastrous - is possible)
Open globe procedures (s/t trauma or planned - GA to ↓likelihood of moving/coughing/↑IOP/extruding ocular contents)

Front 16

If at all possible, what type of anesthesia is preferred for eye surgery?

Back 16

MAC (generally + ocular regional)

Front 17

What meds increase/decrease/have no or variable effect on IOP?

Back 17

Increase IOP:
-Succinylcholine (can attenuate this with defasc dose of ndNMB).
Etiology: tonic contraction of extraocular muscles, choroidal vascular dilation, relaxation of ocular smooth muschle.
Pre-tx of Sux: ndNMB defasc, IV Lidocaine, IV Diamox/ACTZ 20' before Sux, IV Propanolol

Decrease IOP:
-N2O & volatile inhalants
-IV: propofol, etomidate, thiopental.
-Opioids.

No effect on IOP:
-ndNMBDs

Variable effect on IOP:
-Ketamine (↑IOP in high doses)

Front 18

What are some issues in managing an open globe procedure?

Back 18

May be a penetrating injury.

Facing implementation of GA in face of a full stomach if it is s/t trauma.

Cannot insert NGT to aspirate stomach s/t risk of coughing/retching -->extrusion of ocular contents.

Avoid ↑HR/coughing/ bucking/straining d/t danger of extruding ocular contents.

Induction:
-Avoid Sux
-Narcotics & IV Lidocaine to blunt SNS response to DL
-LTA
-Use Hi-dose ndNMBDs (ROC) or mask to deep anesthesia, use LTA and insert ett.
-Use cricoid pressure
-Use PNS to adequately judge depth of paralysis before DL.

-If you have to use Sux, you generally have to give enuf ndNMBD to make patient weak --> educate the pt this will happen so they won't struggle.

Emergence: prevent bucking and coughing to prevent ↑IOP and rebleeding. Weigh the risk of aspiration vs the benefit of extubating deep. (no answer for sure - per pt condition)

Front 19

What is the most common type of glaucoma?

Back 19

Open angle glaucoma: aka chronic glaucoma; s/t sclerosis of the trabecular mesh network imparing drainage of a.h.

Front 20

How do you treat the oculocardiac reflex?

Back 20

Asking surgeon to release traction is adequate tx.

If bradycardia persists and causes hemodynamic instability, give atropine 10 mcg/kg.

Front 21

What causes narrow angle glaucoma?

Back 21

iris and cornea touching and obstructing a.h. outflow (can be cause by mydriatics).

Front 22

What is a consideration of the anti-glaucoma drug echothiopate?

Back 22

It is an irreversible cholinesterase inhibitor - it will prolong the action of Sux and ester LAs.

Front 23

What types of LAs are used in eye & nasal surgery?

Back 23

Tab says few systemic effects s/t small doses & relative dilution.

ESTERS:
-Cocaine: 1.5-3.5 mg/kg; nasal packing for eye surgeries (?)
-Tetracaine: DoA 30'; rare systemic effects b/c it's rapidly hydrolyzed; burns on placement of drops.
-Proparacaine: DoA is 15'; rapid onset; burns a little.
-Duration of all of these is prolonged by echothiopate.

AMIDES:
Lidocaine
Ropivicaine
Bupivicaine

Front 24

What are sulfur hexafluoride and perfluoropropane?

Back 24

Inert gases used to form gas bubbles in tx of displaced/detached retina.

Avoid N2O or turn off 15 minutes before gas bubble insufflated.

Front 25

Most IV and anesthetic drugs decrease IOP. What are some notable exceptions?

Back 25

Ketamine: increases IOP

Sux: Increases IOP s/t fasciculation of extraocular muscles.
-Increases IOP by 8 mmHg for 1-4 minutes & returns to baseline in about 10 minutes.
-Attenuate this effect by pretx with ACTZ (↓A.H. production) or ndNMBDs.

Front 26

What are some anesthetic considerations of strabismus?

Back 26

Most common ocular surgery for children...correct before 4 months old to prevent perm visual defects.

-Strabismus may be only marker for undx'ed NM dz in otherwise health looking child.

-All children getting GA for ophth. surgery should be screened for family hx of MH and hx of MH associated sx (masster muscle spasm, increased temperature). Remove vaporizers, flush circuit, change CO2 absorber.
-Use TIVA and avoid triggering agents.

***TAB: the #1 early sx of MH is unexplained sudden rise in EtCO2***

-High risk of eliciting oculocardiac reflex.

PONV - Can be due to diploplia/dbl vision postop; limit opioids, give intraop antiemitics.

-Avoid Ketamine b/c it CAUSES nystagmus
-Avoid Sux b/c it can create issue with muscle tone which can confound the surgeons.
-Min NMBDs d/t potential interference with extraocular muscles.

Front 27

If a child for opth. surgery is known to have a NM dz, what types of preop screening should they have?

Back 27

Recent cardiac eval including ECG and Echo if indicated.

Front 28

What are some classes of drugs used to treat glaucoma?

Back 28

Alpha agonists (phenylephrine, epi)

Beta antagonists (timolol - nonselective)

Carbonic Anhydrase Inhibitors (ACTZ)

AChesterase Inhibitor: Echothiopate - which in particular prolongs actions of sux, -curiums and ester LAs; probably Esmolol and Cleviprex, too.)

Front 29

What are some considerations when preparing an elderly patient for ophthalmic surgery under RA?

Back 29

-Mgmt of anesthesia will be largely based on the elderly patient's comorbidities.
-Elderly patients often present with a polypharmacy that will impact anesthesia.

-Evaluate ability of elderly patient to lie still and cooperate.
-Assess for hx of claustrophobia and/or acute anxiety attacks.
-Review med list to determine what drugs should/should not be continued before surgery.
(Example - omit diuretics b/c hard to lie still with a full bladder; continue miotics)
-Baseline ECG reviewed on every elderly patient and be av. for comparison in event of change.
-Labs not routine, but warranted if patient on antiPLT, anticoags, or as medically necc.
-Adminstration of atropine: risk of cardiac dysrhythmias and increasing cardiac deman in elderly vs. eliciting oculocardiac reflex..

Front 30

How long should nitrous be avoided after SF6 bubble is used for tx of retinal detachment?

Back 30

At least 10 days after retinal repair with SF6.

Front 31

What equipment must be available when placing regional anesthesia under sedation for opth. surgery?

Back 31

-Functional IV line.
-Monitors: EKG, NIBP, pulse ox, EtCO2
-Suction
-Oxygen: bag/valve/mask
-Airway Equipment: oral airways, laryngoscopes with blades, etts, LMAs
-Anesthesia Meds: inductin agents, paralytics, analgesics, amnestics.
-ACLS meds and equipment.

Front 32

When would you need to convert to a GA if administering a regional ocular anesthesia?

Back 32

In event of IV or Optic Nerve Sheath injection of LA or resuscitation in event of a respiratory or cardiac arrest.

Front 33

What are the primary advantages and limiatations to the retrobulbar and peribulbar blocks, respectively?

Back 33

RETROBULBAR
Adv: Quick onset
Limit: often need to block CN VII (facial) to stop eyelid motion.

PERIBULBAR:
Adv: Reduced risk of injury to optic nerve, globe perf, and subdural injection.
Limit: causes conjunctival swelling which may disrupt surgical field.

Front 34

Why are sux and ketamine generally avoided?

Back 34

B/c of their potential for increasing IOP.

Front 35

What are the most common injuries associatedd with anesthesia for opthalmic surgery?

Back 35

**The article that Tab sent out stated that corneal abrasion is the most common injury - if it was a choice on the test I would pick it first**

Most complications r.t anesthesia for opth surgery are sustained during ocular blocks.
-Retrobulbar hemm.:s/t direct needle trauma to orbital vessels; may ↑IOP

-IV injection of LA: into local vessels with flow into the cerebral circ -->may see sz.

Optic Nerve Sheath injection: inj of LA into sheath surrounding CN II; which comm with midbrain via optic chiasma; may result in respiratory arrest.

Globe Rupture: "You'll shoot your eye out, kid." Caused by direct needle trauma to globe - i.e.=you poked a hole in your patient's eyeball; may result in ↑IOP, ↓function; intraocular hemm., and pain.

Prolonged nerve/muscle palsy: caused by direct inj of LA into muscle or nerve; causes prolonged ptosis, diploplia and pain.

Front 36

Three differences between retrobulbar and peribulbar block.

Back 36

PENETRATION OF BULBAR FASCIA: With retrobulbar block, needle punctures bulbar fascia (there is a "pop") and enters orbital muscle cone. With peribulbar block, the needle is directed parallel and lateral to bulbar fascia rather than passing thru it.

VOLUME OF LA:
Retrobulbar: 2-4 ml of LA
Peribulbar: 4-12 ml of LA
LA usually Lidocaine/bupivicaine combo.

ASSESSMENT OF EFFICACY:
Retrobulbar - can be eval'ed in 2 minutes.
Peribulbar - may take 10-20 ' for adequate anesthesia/akinesia.

Front 37

Timolol is given to _____ _____ ______ production.

Back 37

Timolol is given to decrease aqueous humor production.

Nonsel beta antagonist.

Syst Effects: bradycardia, bronchospasm, CHF, HOTN.

Front 38

What is an easy way to remember what CNs control what eye muscles?

Back 38

Superior Oblique is CN IV (trochlear)

Lateral Rectus is CN VI (Abducens)

All the rest of CN III (Oculomotor)

Front 39

How can we attenuate claustrophobia in a pt getting eye surgery?

Back 39

-Lift drapes so they are not directly touching patient.
-Insuffuse fresh AIR under drape.
-Forced air warmer blowing ambient air & diffuses CO2.

Front 40

What are some common classes/examples of drugs used in the tx of glaucoma?

Back 40

Alpha2-agonists - Alfagan; decrease production and increase outflow of a.h.

Beta-blockers: Timolol/Timoptic; decrease a.h. production

Cholinesterase inhibitors: Echothiopate (prolongs Sux & other cholinesterase metabolized meds) ; increases drainage via miosis.

Front 41

Describe mgmt of anesthesia for glaucoma surgery (trabeculectomy)?

Back 41

Continue glaucoma meds periop.

Avoid venous congestion (which avoids increased IOP)

Determine what meds pt is on & how these may interact with anesthesia meds (ex - timolol or echothiopate)

Front 42

What are some anesthesia considerations of anesthesia surgery?

Back 42

Primarily an elderly pt population with lots of comorbidities.

Anesthesia is usually Topical LA + peri-/retrobulbar block

Use of trochars to insert a flexible lens decreases risk of postop extrusion (smaller incision)

Very short case: 8-10 minutes. May have to turn that room fast. May have to go to preop holding and start medication next patients - if so they need to have all the monitors and airway/anesth. equip as if they were in OR.

Front 43

What are some anesthesia considerations of opthalmic surgery?

Back 43

Primarily an elderly pt population with lots of comorbidities.

Anesthesia is usually Topical LA + peri-/retrobulbar block

Use of trochars to insert a flexible lens decreases risk of postop extrusion (smaller incision)

Very short case: 8-10 minutes. May have to turn that room fast. May have to go to preop holding and start medication next patients - if so they need to have all the monitors and airway/anesth. equip as if they were in OR.

Front 44

What are some procedures used in retinal surgery?

Back 44

Endolaser procedure - use topical LA

Scleral buckle: Either use a cryoprobe exteriorly to "freeze weld" retina to scleral vascular supply OR use a silastic buckle to create a negative pressure that pulls retina against vascular bed.

Pneumatic Retinopexy: gas bubble to push retina against vasc bed; pt prone for a long time.

Front 45

What are some "other" opthamologic proc we reviewed?

Back 45

Dacryocystorhinostomy: relieve tear duct obstruction; involves LA in nasal cavity (cocaine)

Corneal Transplant

Cryosurgery

Frontalis sling: to repair a drooping eyelid

Facial plastics: Brow lift; Blethoplasty --> a cough will cause a hematoma which can have drastic negative results.

Front 46

Basic bullet points about opthalmic procedures.

Back 46

Try to avoid N2O if possible; d/c minimum of 20 minutes before injection of gas bubble (washout 90% complete in 10 minutes)

Be skilled at providing MAC without pt coughing or bucking.

Big issues: cooperative rel with surgeon; very old and very young pts may not be able to be still; be able to manage/prevent moving/coughing/bucking.

Being a distance away from airways is common.

Front 47

What are some procedures used in retinal surgery?

Back 47

Endolaser procedure - use topical LA

Scleral buckle: Either use a cryoprobe exteriorly to "freeze weld" retina to scleral vascular supply OR use a silastic buckle to create a negative pressure that pulls retina against vascular bed.

Pneumatic Retinopexy: gas bubble to push retina against vasc bed; pt prone for a long time.

Front 48

What are some "other" opthamologic proc we reviewed?

Back 48

Dacryocystorhinostomy: relieve tear duct obstruction; involves LA in nasal cavity (cocaine)

Corneal Transplant

Cryosurgery

Frontalis sling: to repair a drooping eyelid

Facial plastics: Brow lift; Blethoplasty --> a cough will cause a hematoma which can have drastic negative results.

Front 49

Basic bullet points about opthalmic procedures.

Back 49

Try to avoid N2O if possible; d/c minimum of 20 minutes before injection of gas bubble (washout 90% complete in 10 minutes)

Be skilled at providing MAC without pt coughing or bucking.

Big issues: cooperative rel with surgeon; very old and very young pts may not be able to be still; be able to manage/prevent moving/coughing/bucking.

Being a distance away from airways is common.