Mod9: Oculocardiac Reflex

Question 1

_{Ocular Physiology}

Oculocardiac Reflex

^Innervation

Answer 1

Trigeminal (V) nerve afferent pathway

Vagus (X) nerve efferent pathway

_{Other ways to remember Innervation of the OCR}

Five & dime reflex

^{(Five for CN V & dime for CN X)}

or

TAVE!!!!

Trigeminal Afferent - Vagus Efferent

Question 2

_{Ocular Physiology}

Oculocardiac Reflex

^Causes:

Answer 2

Traction extraocular muscles

^{(Esp. medial rectus)}

Pressure on globe

Retrobulbar block

Ocular manipulation

Question 3

_{Ocular Physiology}

Oculocardiac Reflex

^{Most commonly seen in which types of surgeries?}

Answer 3

Pediatrics

Strabismus surgery

Question 4

_{Ocular Physiology}

Oculocardiac Reflex

^{Manifestations:}

Answer 4

Bradycardia (most typical)

Bigeminy

Nodal

Ectopic beats

ASYSTOLE

Nausea

Question 5

_{Ocular Physiology}

Attenuation of Oculocardiac Reflex

^{Is Atropine prophylaxis useful?}

Answer 5

Atropine immediately prior to surgery more effective

than IM premed (not effective)

^{0.4 mg IM → no vagolytic effect after 60min → no value in prevention or treatment}

^{0.4 mg IV→ effective for 30min in preventing bradycardia a/w OCR}

Routine prophylaxis controversial

^{because Doses > 0.5 mg IV → tachycardia → detrimental in pt’s with CAD}

Question 6

_{Ocular Physiology}

Attenuation of Oculocardiac Reflex

^{What else could you do besides Atropine prophylaxis, to prevent OCR?}

Answer 6

Retrobulbar block once set, no problem!!!

^{(but may elicit during placement)}

Deep inhalational anesthetic

Question 7

_{Ocular Physiology}

Oculocardiac Reflex: Treatment

Answer 7

Stop surgical stimulation/traction until HR increases

Confirm adequate anesthetic depth

Infiltration local anesthetic into rectus muscles

^{(Takes time)}

Reflex often fatigues (self-extinguishable) without additional therapy

Atropine 10ug/kg if arrhythmia persists

Question 8

_{Ophthalmic surgery}

Preoperative Evaluation

^{General patient population typically of what age?}

Answer 8

< 10 yo

or

> 55 yo

Question 9

_{Ophthalmic surgery}

Preoperative Evaluation of Pediatric patients

^{concentrates on h/o:}

Answer 9

Congenital

Metabolic

Musculoskeletal disorders

Question 10

_{Ophthalmic surgery}

Preoperative Evaluation of Adults patients

^{concentrates on h/o:}

Answer 10

Multiple health problems

^{CHF, HTN, COPD, DM, dementia}

Determine optimization

Continue routine medications in general

^{HOLD ASA/coumadin}

Preoperative lab testing

^{Based on history/physical}

^{Many on anticoagulants → PT/PTT necessary}

Question 11

_{Ophthalmic surgery - Preoperative Evaluation}

Ophthalmic drugs they are already on

^Concern:

Answer 11

Consider anesthetic ramifications of ophthalmic drugs

_{Topically administered drugs are absorbed by vessels in conjunctival sac and nasolacrimal duct mucosa at rate intermediate between absorption following IV/SQ administration.}

_{Ophthalmological topical phenylephrine (10%)is used to dilate eye for surgery.}

_{1 drop = 5mg.}

_{Toxic dose of phenylephrine = 10mg!!​}

Question 12

_{Ophthalmic surgery - Preoperative Evaluation}

Topical or regional vs. general anesthesia

^{Evaluate suitability for this through:}

Answer 12

Ability to follow commands

Ability to lie motionless (tremors, chronic cough, arthritis)

Ability to lie flight (SOB, orthopnea, dyspnea)

Ability to tolerate face covered with surgical drapes (claustrophobia)

Question 13

_{Ophthalmic surgery}

Anesthetic Techniques

Answer 13

Regional anesthesia

Topical anesthesia

General anesthesia

Question 14

_{Ophthalmic surgery - Anesthetic Techniques}

Regional anesthesia

^Options:

Answer 14

Retrobulbar block

Peribulbar block

Facial nerve block

Question 15

_{Ophthalmic surgery}

Anesthetic Techniques

^{Which is safer?}

Answer 15

Inconclusive evidence that one is safer than other

Question 16

_{Ophthalmic surgery}

Anesthetic Techniques

^{Factors influencing choice:}

Answer 16

Nature/duration surgery

Coagulation studies

Patients ability to communicate/cooperate

Often dictated by the surgeon

Question 17

_{Ophthalmic surgery}

Choice of Anesthetic Techniques

^{made jointly by:}

Answer 17

Patient

Anesthetist

Surgeon*

^{(Surgeon often dictates choice of anesthesia)}

Question 18

_{Ophthalmic surgery - Regional Anesthesia}

Peribulbar block

^{Characteristics:}

Answer 18

Local anesthesia injected outside cone

Safer

Less pain

Onset longer (20”)

Question 19

_{Ophthalmic surgery - Regional Anesthesia}

Retrobulbar block

^{Characteristics:}

Answer 19

LA injected behind eye into cone formed by extraocular muscles

More painful

Performed by surgeon or trained anesthesia provider

Question 20

_{Ophthalmic surgery - Regional Anesthesia}

Peribulbar/Retrobulbar Block

^{Local anesthetic solutions used:}

Answer 20

2-5mls Lidocaine 2% - Bupivacaine 0.75% - Ropivacaine

Epinephrine may be added

^{(1:200,000 or 1:400,000 solution)}

Wydase

(hydrolyzes connective tissue)

^{may be added to enhance <strong>spread</strong> local anesthetic}

Question 21

_{Ophthalmic surgery - Regional Anesthesia}

Peribulbar/Retrobulbar Block

^{Performed by:}

Answer 21

Surgeon

or

Anesthesia provider

Question 22

_{Ophthalmic surgery - Regional Anesthesia}

Peribulbar/Retrobulbar Block

^{Patient’s disposition during the procedure:}

Answer 22

Patient may be awake or sedated

Either way, the patient must not move as the block is administered

Sedation may include barbiturate, propofol, short acting narcotic, or benzodiazepine

Question 23

_{Ophthalmic surgery - Regional Anesthesia}

Peribulbar/Retrobulbar Block

^{Pressure is applied afterward administration of the block for what purpose?}

Answer 23

Enhance spread of anesthetic

Reduce intraocular pressure

Maintain normal orbital anatomy

Question 24

_{Ophthalmic surgery - Regional Anesthesia}

Peribulbar/Retrobulbar Block

^{Successful block is evidenced by:}

Answer 24

Anesthesia

Akinesia

Abolished Oculo-Cardiac Reflex

^{(Remember: OCR can be ellicited by block placement)}

Question 25

_{Ophthalmic surgery - Regional Anesthesia} **Facial nerve block** ^{What is it used for?}

Answer 25

Augment retro/peribulbar Prevents squinting/blinking eyelid Allows for placement **lid speculum** ^{(lid speculum: instrument that holds the eyelid open)}

Question 26

_{Ophthalmic surgery - Regional Anesthesia} **Facial nerve block** ^{Complications:}

Answer 26

Vocal Cord paralysis Laryngospasm Dysphagia Respiratory distress

Question 27

_{Ophthalmic surgery} **Regional Anesthesia** ^{Complications:}

Answer 27

Stimulation OCR (Occulo-Cardiac Reflex) **Circumorbital hematoma/superficial hemorrhage** Retrobulbar hemorrhage **Globe penetration/intraocular injection (Accidental)** ^{=> Retinal detachment/permanent loss vision} Trauma optic/orbital cranial nerves **Intraarterial injection of LA** ^{Most common => Immediate convulsions!!!}

Question 28

_{Ophthalmic surgery - Complications of Regional Anesthesia} **Optic nerve sheath injection** ^{Manifestations:}

Answer 28

**Orbital epidural anesthesia/post retrobulbar syndrome (spread LA into CSF)** =\> Apprehension =\> LOC/seizures =\> Apnea within 20min/Resolves within 1h _{Accidental access to CSF occurs secondary to perforation of the meningeal sheaths that surround the optic nerve resulting in a total spinal}

Question 29

_{Ophthalmic surgery - Complications of Regional Anesthesia} **Optic nerve sheath injection** ^Treatment:

Answer 29

Supportive/PPV

Question 30

_{Ophthalmic surgery} **Regional Anesthesia** ^{Contraindications}

Answer 30

Refusal from the patient Bleeding disorder/anticoagulation ^{d/t ↑ risk retrobulbar hemorrhage} Open eye injury ^{b/c ↑ pressure from LA→ extrusion intraocular contents}

Question 31

_{Ophthalmic surgery} **Topical Anesthesia** ^Benefits:

Answer 31

Growing trend Eliminates need for anesthetic injection Less traumatic/fewer complications

Question 32

_{Ophthalmic surgery} **Topical Anesthesia** ^{Appropriate for which procedures?}

Answer 32

**Anterior chamber procedures** ^Cataracts **Trabeculectomy** ^{Treatment glaucoma}

Question 33

_{Ophthalmic surgery} **Topical Anesthesia** ^{Not appropriate for which procedures?}

Answer 33

**Posterior chamber procedures** ^{Vitrectomy/Scleral buckle (retinal detach.)}

Question 34

_{Ophthalmic surgery} **Topical Anesthesia** ^{Best suited for surgeons that are:}

Answer 34

Fast but gentle surgical technique who do not require akinesia eye

Question 35

_{Ophthalmic surgery} **Monitored Anesthesia Care/IV Sedation** ^{General Principles}

Answer 35

Avoid deep sedation Avoid under sedation Common techniques used

Question 36

_{Ophthalmic surgery - Monitored Anesthesia Care/IV Sedation} **Avoid deep sedation** ^why?

Answer 36

Risk apnea (bed turned 180˚) Unintentional patient movement

Question 37

_{Ophthalmic surgery - Monitored Anesthesia Care/IV Sedation} **Avoid under sedation** ^because:

Answer 37

Block placement quite painful HTN/Tachycardia (CAD)

Question 38

_{Ophthalmic surgery} **Monitored Anesthesia Care/IV Sedation** ^{Common techniques used}

Answer 38

**Propofol** in small bolus doses ^{→ provide brief period unconsciousness} Short acting narcotic (**remi/alfentanil/fentanyl**) in small bolus doses ^{→ brief period intense analgesia} **Midazolam** w/ or w/o **fentanyl** ^{→ minimal relaxation/amnesia} Administer drugs in small doses and reduce accordingly if concomitant use of more than one type used

Question 39

_{Ophthalmic surgery} **Monitored Anesthesia Care/IV Sedation** ^Monitoring

Answer 39

**Ventilation/oxygenation** ^{Equipment to maintain airway and provide PPV must be immediately available} **Continuous ECG** ^{Occulo-Cardiac Reflex}

Question 40

_{Ophthalmic surgery} **General Anesthesia** ^Indications:

Answer 40

Infants and children ^{(cannot remain montionless)} Adults with certain conditions **Procedures \> 2 hours =\> GA** ^{(Cannot remain montionless for too long)} **Open eye injuries =\> GA**

Question 41

_{Ophthalmic surgery} **General Anesthesia** ^{Indicated for Adults with:}

Answer 41

Severe claustrophobia History of acute anxiety attacks Inability to communicate or cooperate Inability to lie flat or motionless ^{(d/t respiratory issues)}

Question 42

_{Ophthalmic surgery} **General Anesthesia** ^{Techniques and agents dictated by:}

Answer 42

Patient's medical history and surgical procedure