Ophthalmic part 2 Flashcards
Local anesthetics for eye surgery are
most often placed by surgeon
toxicity is rare but may occur
Topical agents used for eye surgery include
tetracaine (most common) proparacaine bupivacaine lidocaine cocaine
Topical eye medications enter bloodstream through
outer eye membrane & lacrimal apparatus
Measures to reduce the amount of topical eye medication that enters the bloodstream include:
close eyes for 60 seconds after drops instilled to encourage absorption by eye
avoid blinking
block tear outflow canal (place index finger over medial canthus)
The most frequently performed intraocular procedures include
cataract & vitreoretinal surgeries
______ for cataract is effective in providing adequate analgesia
topical anesthesia
Ocular regional anesthesia is the most common and effective way to consistently
produce analgesia & akinesia of the eye and eyelids
Ocular local anesthesia includes
peribulbar block & retrobulbar block
To provide ocular regional anesthesia, one may block ______ outside of the eye
anesthetize multiple cranial nerves (III, IV, V, VI, or VII)
orbital epidural space
facial nerve block
A peribulbar block is injection of local anesthesia
outside** the muscle cone
Peribulbar block provides
analgesia & akinesia of the eye
relatively low complication rate
Disadvantages of peribulbar block includes:
large volumes injected (6-8 mL) may increase IOP slower onset of action (5-10 minutes) -possible perforation of globe -vertical diplopia (myotoxicity from local anesthesia)
To perform the peribulbar block,
have the patient look straight ahead- avoid vasculature & optic nerve
use dull, short-beveled 25-27 gauge, 22 mm needle
insert needle in lateral aspect of the inferotemporal quadrant & superiornasal
do not insert beyond 25 mm or pierce muscle cone
ASPIRATE before slowly injection
6 mL of LA
lidocaine + bupivacaine
A retrobulbar block is injection of local anesthesia
INSIDE** the muscle cone
provides analgesia & akinesia of the eye
The ______ block has a higher complication rate
retrobulbar block
Describe how to perform the retrobulbar block.
insert 25 gauge needle through lower lid at the junction of the lateral third & medial 2/3 of the inferior orbital edge
advance 25-35 mm toward apex of orbit (19-31 mm safest)
ASPIRATE and inject 2-5 mL LA
lidocaine & bupivacaine most common
Complications of the retrobulbar block include
complications occur in 1:500 blocks trauma to optic nerve vision loss retrobulbar hemorrhage globe perforation oculocardiac reflex brainstem anesthesia (injection into optic nerve sheath) intravenous or intra-arterial injection seizure respiratory or cardiac arrest
Complications of the retrobulbar block usually occur within
15 minutes after block
standard monitors, emergency equipment, & vigilance
Contraindications to the retrobulbar block include:
bleeding disorders, anticoagulation, extreme myopia, open eye injury
A sub-Tenon’s (Episcleral) block is local anesthetic placed into
potential space between Tenon’s capsule & the sclera
inferonasal conjunctival fornix is most commonly used
Describe how to perform Sub-Tenon’s block.
direct needle posteriorly following curve of globe
superficial injection allows LA to spread circularly around scleral portion of globe (3-5 mL)
larger volume (8-11 mL) allows spread to extraocular muscle sheaths
Deep injection- posterior intra & extraconal spaces is most common
A facial nerve block may be performed to
prevent excessive blinking during eye surgery
periocular branches of the facial nerve
30% of eye injury claims are due to
patient movement during ophthalmic surgery- blindness was the outcome in all cases
Describe pediatric considerations for ophthalmic surgery
assess for congenital, metabolic, MSK, and malignant hyperthermia
Describe the elderly considerations for ophthalmic surgery.
HTN, DM, CHF, pulmonary disease, mental status, arthritis, polypharmacy, cardiac disease
Most eye operations can be performed under
regional anesthesia & sedation
-same standard of care
NPO status is even more important
Unique preoperative considerations include:
can patient lie flat, lie still, claustrophobia, etc.?
make sure patient knows what to expect for anesthetic
considerations for GETA
general anesthesia for infants and young children
temperature, fluids, & foley
Indications for general anesthesia include:
pediatric patient, patient’s lack of cooperation, severe claustrophobia, inability to communicate, inability to lie flat, open-eye injuries, procedures with durations greater than 2 hours
Disadvantages of general anesthesia for eye surgeries include
N/V, retching/bucking, increased intraocular pressure, aspiration, complications secondary to other medical problems, time & expense
For sedation for blocks consider use of
short-acting agents to provide amnesia, analgesia, & immobility
-prevent cardiac or respiratory side effects
Intraoperative medications for eye procedures include
fentanyl, alfentanil, remifentanil, midazolam, propofol, dexmedetomidine
-consider synergistic effects, dosing for elderly/pediatrics, circulation time
Describe intraoperative management for eye procedures:
unnecessary to maintain sedation if block is adequate OR table turned 90 or 180 degrees standard monitors oculocardiac reflex temperature fluids "Light" GA for little stimulation hypotension oxygen & cautery risk of corneal abrasion, retinal artery occlusion
Describe postoperative management for eye procedures:
PONV
postop eye pain is unusual- corneal abrasion & acute intraocular HTN (treat with mannitol/acetazolamide)
elderly patients with history of MI are at increased risk for ischemic events even under LA- consider preop beta-blockers
Common eye procedures include
strabismus repair, foreign body removal, conjunctival flap, corneal transplant, trabeculectomy, penetrating eye injuries, cataract, ptosis surgery, eyelid reconstruction, blepharoplasty, retinal detachment repair (scleral buckling), vitrectomy, ophthalmic oncology
Strabismus is an
ocular misalignment
most common ophthalmic condition requiring surgical repair in children
Intervention for strabismus should occur before
4 months to allow normal stereoscopic visual development
Strabismus surgery
lengthens/shortens ocular muscles to straighten eyes & allow binocular vision
Strabismus is performed under
GA
minimal EBL
table turned
With strabismus concerns include
oculocardiac reflex, increased risk of MH, PONV
Describe the oculocardiac reflex with strabismus
increased PaCO2 shown to decrease OCR during strabismus
stop stimulation, administer anticholinergics, LA infiltration
Describe increased risk of MH with strabismus.
associated with underlying myopathy- higher risk of MH
avoid triggers
monitor: temp, EKG, EtCo2, muscle rigidity
ABG: low PaO2, high PaCO2, hyperkalemia, acidosis
Dantrolene 2.5 mg/kg IV up to 10 mg/kg
PONV with strabismus is due to the
ocular-emetic reflex
- possible disruption of surgical repair
prevention: hydration, minimize opioids, avoid N2O, propofol, La infiltration near extraocular muscle, antiemetics
Penetrating eye injury concerns include:
full stomach precautions
aspiration risk
prevent increase in IOP- succinylcholine (increases within 1 minute, peaks with 9 mmHg), coughing
open globe- succinylcholine risk vs. benefit; laryngoscopy & intubation increases IOP, consider non-depolarizing NMB for RSI
Open globe with a full stomach is an
EMERGENCY SURGERY WITH GA**
The do’s and don’ts to prevent aspiration with open globe include:
do NOT attempt to evacuate contents using NGT preop
DO administer metoclopramide IV, H2 antagonists (ranitidine), non-particulate antacid prior to induction
-Do NOT attempt regional anesthesia (LA injection will increase IOP)
-DO attempt RSI using cricoid pressure avoiding PPV
-DO extubate awake, spontaneously breathing, head turned to side
Preventing increase in IOP with open globe includes:
avoid direct pressure on eye avoid Trendelenburg position avoid regional anesthesia avoid increases in CVP avoid drugs that increase IOP avoid agitation in young children
Anesthesia complications for eye surgeries include
retrobulbar hemorrhage globe puncture optic nerve sheath trauma intravascular injection ocular ischemia extraocular muscle palsy & ptosis facial nerve blocks oculocardiac reflex corneal abrasion central retinal artery occlusion (prolonged pressure)
Retrobulbar hemorrhage results from
trauma to an orbital vessel
moves eyeball forward
Venous hemorrhages have
slow onset, while arterial hemorrhage has rapid onset & pronounced proptosis
Lateral canthotomy may be indicated if the hemorrhage is
not resolved by digital pressure
- increase orbital space by cutting the lateral canthus
- reduces orbital pressure that results from hemorrhage
- place hemostat in temporal direction along lateral canthus 4-6 mm and clamp hemostat
- use scissors to incise the crush marks left by hemostat
- control local bleeding
Globe puncture can be due to
sharp and dull needles both reported to have penetrated the eye during injections
globe can burst apart from IOP caused by injection
Risks for globe puncture include
myopic eye, scleral thinning, scleral buckling, bulging of sclera
Prevention of globe puncture includes
avoid supranasal position of gaze
direct needle away from axis of globe during insertion
insert needle slowly with bevel towards globe
never forcefully inject LA
use modified techniques
Symptoms of globe puncture include:
increased resistance to injection
dilation/paralysis of pupil
increased IOP
hemorrhage
The optic nerve sheath surrounds
the optic nerve
The optic nerve sheath is composed of
meninges of brain
- outer sheath contains dura mater
- inner sheath consists of arachnoid & pia mater
- subarachnoid space contains CSF and is continuous with optic chiasm
- dura splits into two layers at optic foramen
When evaluating for optic nerve sheath trauma,
observe contralateral pupil before block
if contralateral pupil constricted–> dilated after block–> assume subarachnoid/subdural injection and prepare for respiratory arrest
_______ has been reported after ocular blocks.
retinal vascular occlusion or thrombosis
Ocular ischemia may be a result of
decreased pulsatile ocular blood flow after blocks
optic nerve atrophy reported after regional block or GA
Transient symptoms of optic nerve injury include
contralateral amaurosis or respiratory arrest; or vascular occlusion/thrombosis which may lead to loss of vision
______ may occur secondary to direct nerve trauma.
Bell’s palsy
Prevention of facial nerve block paralysis includes:
avoid large volume LA, avoid Nadbath technique in certain patients, seated/lateral position to protect airway, intubate if airway concerns
With paresis of the vagus, glossopharyngeal, and spinal accessory nerves,
dysphagia, hoarseness, coughing, and respiratory distress may be seen
- nerves exit skull 10 mm medial to CN VII
- LA injected for CN VII block can reach these nerves
- Unilateral vocal cord paralysis
Extraocular muscle palsy is a result of
inferior muscle palsy reported after retrobulbar anesthesia
Symptoms of extraocular muscle palsy include
persistent vertical diplopia
surgical intervention may be indicated
Prevention of extraocular muscle palsy includes
avoid needle contact with extraocular muscles, avoid deep orbital penetration, avoid angling needle toward visual axis of globe
Myotoxicity of LA may cause postoperative
diplopia and/or ptosis
